Preparation, Characterization and Application of a Low Water-Sensitive Artemisia sphaerocephala Krasch. Gum Intelligent Film Incorporated with Anionic Cellulose Nanofiber as a Reinforcing Component

A low-water-sensitive Artemisia sphaerocephala Krasch. gum (ASKG) based intelligent film was developed. Red cabbage extracts (RCE) was selected as a natural pH-sensitive indicator, and anionic cellulose nanofiber (ACNF) was added as a hydrophobic and locking host. The zeta potential, rheology, Fourier-transform infrared spectroscopy, X-ray diffractometry, and release results indicated that the RCE was locked by the ACNF via electrostatic interactions, moreover, broke the original complicated network and ordered arrangement of polymer molecules in the developed intelligent films. RCE addition decreased the tensile strength, oxygen, and water vapor barrier properties and light transmission of the developed intelligent films, while increasing the elongation at break. The films could respond to buffer solutions and NH3 through different color changes. The developed intelligent film was hydrophobic, which could precisely detect the freshwater shrimp freshness in real time via color changes, which indicated that the films have potential in intelligent packaging and gas-sensing label fields.


Introduction
Biomass packaging materials have been extensively investigated to replace synthetic plastics, because of their low cost, easy processability, non-toxicity, and biodegradability, as awareness of environmental protection and food safety has increased [1]. In recent years, commercial intelligent labels or films, such as the Timestrip ® , 3M™MonitorMark™, CheckPoint ® , and Ageless Eye ® , appear in our daily lives [2]. However, the raw materials and indicators that are used are organic synthetic substances or heavy metals, which can harm the ecosystem and people's health, and pollute packaged food. Naturally degradable and edible intelligent films or labels have received extensive attention from researchers to resolve this problem. In recent years, polysaccharides, such as gelatin [3], chitosan [4], gellan gum [5], and starch [6] based intelligent films, have been investigated to detect seafood and meat freshness and they showed good detecting effects.
Synthetic indicators, such as methylene blue [7], bromocresol green [8], and chlorophenol red [9], were used first in intelligent packaging films. However, these indicators can pollute packaged food and may pose a harmful risk to the ecosystem and people's health [10]. To resolve those issues, natural indicators, such as curcumin [11][12][13], anthocyanins from black carrot [14], red cabbage [15,16], purple-fleshed sweet potato [17], and roselle [18], have been used to replace synthetic indicators in edible intelligent packaging films according to recent reports [19], because they are non-toxic [20] and 2.3.14. Freshness Detection Test Before testing, the color parameter of the AFR-10P film (15 mm × 15 mm, ~0.01 g) was tested. The sample was placed at a 43% humidity for 24 h. Subsequently, 25 g of freshwater shrimp was used in the experiment at 20 °C. When the color of the film changed, the color parameter should be tested immediately. Figure 1 shows the specific test diagram.

Zeta Potential Analysis
The related data of RCE, ACNF, AFR0, AFR5, AFR10, and AFR15 solutions in Figure 2 indicate that the charge of the RCE solution is −6.1 mV [38] and the charge of ACNF solution is −47.0 mV [39]. The charge of the AFR0 solution is −17.4 mV, which is related to the offset between the positive and negative charges [39]. When RCE increased from 0% to 15%, it also increased from −17.4 to −12.3 mV, which indicates that an electrostatic interaction between the flavylium cations in RCE and the COO − in ACNF occurred. that the charge of the RCE solution is −6.1 mV [38] and the charge of ACNF solution is −47.0 mV [39]. The charge of the AFR0 solution is −17.4 mV, which is related to the offset between the positive and negative charges [39]. When RCE increased from 0% to 15%, it also increased from −17.4 to −12.3 mV, which indicates that an electrostatic interaction between the flavylium cations in RCE and the COOin ACNF occurred.  Figure 3 shows that the viscosity of all film-forming solutions decreased with the shear rate increased (characteristics of non-Newtonian fluids), which indicates that the hydrogen bonds that were formed by ASKG, ACNF, glycerol, and RCE were destroyed by the shearing force, and the original complicated network structure could not be restored within a certain time [40]. This result is attributed to the small molecular structure of RCE that could penetrate the complicated network structure easily formed among each content, and new hydrogen bonds formed between the ASKG, ACNF, glycerol and RCE. The complex that formed between the RCE and ACNF by the electrostatic attraction also broke the complicated network structure in film-forming solutions.  Figure 3 shows that the viscosity of all film-forming solutions decreased with the shear rate increased (characteristics of non-Newtonian fluids), which indicates that the hydrogen bonds that were formed by ASKG, ACNF, glycerol, and RCE were destroyed by the shearing force, and the original complicated network structure could not be restored within a certain time [40]. This result is attributed to the small molecular structure of RCE that could penetrate the complicated network structure easily formed among each content, and new hydrogen bonds formed between the ASKG, ACNF, glycerol and RCE. The complex that formed between the RCE and ACNF by the electrostatic attraction also broke the complicated network structure in film-forming solutions.   Table 1 shows that the Cross model is suitable for fitting the ASKG/ACNF/RCE film-forming solutions (R 2 > 0.999), and the η0 and K values decreased from 1.3857 to 1.3015 Pa·s and from 2.1880 to 1.8871 s with an increase of RCE from 0% to 15%, respectively. These results are related to the RCE addition, which broke the complicated network structure that formed between the ASKG, ACNF, and glycerol. Entanglements among the ACNF chains weakly decreased the weakly. Moreover, p values ˂ 1 show that all of the solutions were pseudoplastic fluids [41]. These results reveal that RCE changed the network formed by ASKG, ACNF and glycerol molecules.   Table 1 shows that the Cross model is suitable for fitting the ASKG/ACNF/RCE film-forming solutions (R 2 > 0.999), and the η 0 and K values decreased from 1.3857 to 1.3015 Pa·s and from 2.1880 to 1.8871 s with an increase of RCE from 0% to 15%, respectively. These results are related to the RCE addition, which broke the complicated network structure that formed between the ASKG, ACNF, and glycerol. Entanglements among the ACNF chains weakly decreased the weakly. Moreover, p values < 1

Dynamic Rheological Analysis
As shown in Figure 4, all of the film-forming solutions were weak gel systems, because a crossover point between G" and G curves existed [42]. The η* value decreased as angular frequency increasing. The crossover point between G and G" shifted from 3.09 to 3.58 rad/s with an increase of RCE from 0% to 15%, which was attributed to the electrostatic attraction between RCE and ACNF changed the complicated network structure. These results show that RCE exhibited plasticizing effects, to some extent. However, RCE addition did not change the network system properties of the film-forming solutions [43]. These results are agreed with the steady rheological analysis.

FT-IR Analysis
The RCE spectrum shows that the bands at 3308, 1638, 1414, and 1045 cm −1 were related to the O-H stretching vibration in hydroxyl, the C=C stretching vibration in aromatic ring, the C-O bending vibration in phenols, and the O-C stretching vibration in flavonoid, respectively [22]. Figure 5b shows that the bands at 3289, 2927, and 2885 cm −1 of AFR0 film were related to the O-H stretching vibration in hydroxyl, the C-H stretching vibration of the film components, respectively. Bands at 1644 and 1416 cm −1 were related to the C=O stretching vibration and -COO-stretching vibration [44,45]. The bands at 1021, 920, and 868 cm −1 were related to the characteristic stretching vibration of C-O and O-C in pyran ring, respectively [46].
The RCE spectrum shows that the bands at 3308, 1638, 1414, and 1045 cm −1 were related to the O-H stretching vibration in hydroxyl, the C=C stretching vibration in aromatic ring, the C-O bending vibration in phenols, and the O-C stretching vibration in flavonoid, respectively [22]. Figure 5b shows that the bands at 3289, 2927, and 2885 cm −1 of AFR0 film were related to the O-H stretching vibration in hydroxyl, the C-H stretching vibration of the film components, respectively. Bands at 1644 and 1416 cm −1 were related to the C=O stretching vibration and -COO-stretching vibration [44,45]. The bands at 1021, 920, and 868 cm −1 were related to the characteristic stretching vibration of C-O and O-C in pyran ring, respectively [46].  After RCE addition, the band at 3289 cm −1 shifted to a low wavenumber and the band at 2924 cm −1 was enhanced, which indicates that the hydrogen bonds among the ASKG, ACNF and glycerol were broken and new hydrogen bonds formed [47]. Bands at 1644 and 1412 cm −1 broadened and shifted to a low wavenumber, which indicates that an electrostatic attraction occurred between RCE and ACNF [22]. All of those results show that RCE was locked into the intelligent film through electrostatic attraction with ACNF. Figure 6a shows that a weak peak at 11.8 • and two broad peaks at 16.4 • and 22.2 • were the characteristic polysaccharide peaks of ASKG. Figure 6b shows two peaks at 15.4 • and 22.5 • in the XRD pattern of ACNF, which indicates a cellulose I crystal structure [48].

XRD Analysis
Polymers 2020, 12, x FOR PEER REVIEW 9 of 19 After RCE addition, the band at 3289 cm −1 shifted to a low wavenumber and the band at 2924 cm −1 was enhanced, which indicates that the hydrogen bonds among the ASKG, ACNF and glycerol were broken and new hydrogen bonds formed [47]. Bands at 1644 and 1412 cm −1 broadened and shifted to a low wavenumber, which indicates that an electrostatic attraction occurred between RCE and ACNF [22]. All of those results show that RCE was locked into the intelligent film through electrostatic attraction with ACNF. Figure 6a shows that a weak peak at 11.8° and two broad peaks at 16.4° and 22.2° were the characteristic polysaccharide peaks of ASKG. Figure 6b shows two peaks at 15.4° and 22.5° in the XRD pattern of ACNF, which indicates a cellulose I crystal structure [48].

XRD Analysis
The XRD pattern of the AFR0 film ( Figure 6c) shows three characteristic peaks at 10.9°, 16.3°, and 22.3°. The diffraction peaks indicate that ACNF rearranged ASKG molecular chains and the chains blended. After RCE addition, the peak around 16.3° was enhanced, which indicates that RCE addition broke the complicated network structure that formed between ASKG and ACNF by electrostatic interaction. The peak at 16.3° decreased with a further increase in RCE, which indicates that the electrostatic interaction between RCE and ACNF changed the crystal structure of the intelligent film.  Figure 7 shows that three mass loss peaks can be observed in AFR0 film; the mass loss peaks at 69.07, 186.04, and 287.81 °C were the loss of adsorbed water [49], the decomposition of glycerol [23], and the decomposition of ASKG and ACNF [23,50]. After RCE addition, the thermal decomposition temperature of the third mass loss peak shifted from 287.81 °C to 281.38 °C, which indicates that the RCE broke the tightly complicated network structure between the ASKG and ACNF chains. The XRD pattern of the AFR0 film ( Figure 6c) shows three characteristic peaks at 10.9 • , 16.3 • , and 22.3 • . The diffraction peaks indicate that ACNF rearranged ASKG molecular chains and the chains blended. After RCE addition, the peak around 16.3 • was enhanced, which indicates that RCE addition Polymers 2020, 12, 247 9 of 18 broke the complicated network structure that formed between ASKG and ACNF by electrostatic interaction. The peak at 16.3 • decreased with a further increase in RCE, which indicates that the electrostatic interaction between RCE and ACNF changed the crystal structure of the intelligent film. Figure 7 shows that three mass loss peaks can be observed in AFR0 film; the mass loss peaks at 69.07, 186.04, and 287.81 • C were the loss of adsorbed water [49], the decomposition of glycerol [23], and the decomposition of ASKG and ACNF [23,50]. After RCE addition, the thermal decomposition temperature of the third mass loss peak shifted from 287.81 • C to 281.38 • C, which indicates that the RCE broke the tightly complicated network structure between the ASKG and ACNF chains.   Figure 8 exhibits the ACNF morphology and the flat/cross-sectional surfaces of the intelligent films. Figure 8A shows that the 1% of ACNF solution was a transparent milky white, which indicates that the ACNF was at the nanoscale. The ACNF showed a filament structure with a nanometer diameter and a micron length, according to the TEM image. The filaments were entangled. As shown in Figure 8B, all of the flat surfaces of the intelligent films were homogeneous, but wrinkled, which is attributed to the long filament morphology of ACNF. Layered structures were visible in the cross-section surface of the AFR0 film, because the peeling effects between the ACNF Thermogravimetric (TG) and derivative thermogravimetric (DTG) curves of ASKG/ACNF/RCE intelligent films.  Figure 8A shows that the 1% of ACNF solution was a transparent milky white, which indicates that the ACNF was at the nanoscale. The ACNF showed a filament structure with a nanometer diameter and a micron length, according to the TEM image. The filaments were entangled.   Figure 8A shows that the 1% of ACNF solution was a transparent milky white, which indicates that the ACNF was at the nanoscale. The ACNF showed a filament structure with a nanometer diameter and a micron length, according to the TEM image. The filaments were entangled. As shown in Figure 8B, all of the flat surfaces of the intelligent films were homogeneous, but wrinkled, which is attributed to the long filament morphology of ACNF. Layered structures were visible in the cross-section surface of the AFR0 film, because the peeling effects between the ACNF and ASKG during brittle fracture in liquid nitrogen. After RCE addition, the layered structures in the  Figure 8B, all of the flat surfaces of the intelligent films were homogeneous, but wrinkled, which is attributed to the long filament morphology of ACNF. Layered structures were visible in the cross-section surface of the AFR0 film, because the peeling effects between the ACNF and ASKG during brittle fracture in liquid nitrogen. After RCE addition, the layered structures in the cross-sectional surfaces of the intelligent films increased, which indicates that the electrostatic attraction between RCE and ACNF broke the arrangement of molecular chains and made the peeling effects of ACNF easier. A further increase in the amount of RCE added, the layered structures in the cross-section surfaces decreased, because new hydrogen bonds formed among the film-forming polymers and the rearrangement of molecular chains occurred. Based on all of the above analyses, the schematic structure of the ASKG/ACNF/RCE intelligent film is shown in Figure 9.  Figure 10 shows that the thickness of the intelligent films slightly increased from 0.061 mm to 0.066 mm, owing to the increase of solid polymers, moreover, the tensile strength decreased from 43.23 to 24.83 MPa, but the elongation at break increased from 56.13% to 75.87% with the increase of RCE from 0% to 15%.  Figure 11 shows that the OP and WVP values of AFR5, AFR10, and AFR15 intelligent films were higher than the AFR0 intelligent film, owing to the electrostatic attraction between RCE and ACNF that broke the tight structure that formed by ASKG, ACNF, and glycerol. With an increase in RCE from 10% to 15%, the two values slightly decreased from 0.0169 to 0.0115 ((cm 3 ·mm)/(m 2 ·day·atm)) and from 4.5859 to 3.8494 × 10 −10 g/(s·m·Pa), respectively. This result is attributed to the formation of a new tight network structure that formed by RCE, ASKG, ACNF and glycerol [51]. The developed intelligent films retained excellent oxygen and water vapor barrier properties.  Figure 10 shows that the thickness of the intelligent films slightly increased from 0.061 mm to 0.066 mm, owing to the increase of solid polymers, moreover, the tensile strength decreased from 43.23 to 24.83 MPa, but the elongation at break increased from 56.13% to 75.87% with the increase of RCE from 0% to 15%.  Figure 10 shows that the thickness of the intelligent films slightly increased from 0.061 mm to 0.066 mm, owing to the increase of solid polymers, moreover, the tensile strength decreased from 43.23 to 24.83 MPa, but the elongation at break increased from 56.13% to 75.87% with the increase of RCE from 0% to 15%.  Figure 11 shows that the OP and WVP values of AFR5, AFR10, and AFR15 intelligent films were higher than the AFR0 intelligent film, owing to the electrostatic attraction between RCE and ACNF that broke the tight structure that formed by ASKG, ACNF, and glycerol. With an increase in RCE from 10% to 15%, the two values slightly decreased from 0.0169 to 0.0115 ((cm 3 ·mm)/(m 2 ·day·atm)) and from 4.5859 to 3.8494 × 10 −10 g/(s·m·Pa), respectively. This result is attributed to the formation of a new tight network structure that formed by RCE, ASKG, ACNF and glycerol [51]. The developed intelligent films retained excellent oxygen and water vapor barrier properties.  Figure 11 shows that the OP and WVP values of AFR5, AFR10, and AFR15 intelligent films were higher than the AFR0 intelligent film, owing to the electrostatic attraction between RCE and ACNF that broke the tight structure that formed by ASKG, ACNF, and glycerol. With an increase in RCE from 10% to 15%, the two values slightly decreased from 0.0169 to 0.0115 ((cm 3 ·mm)/(m 2 ·day·atm)) and from 4.5859 to 3.8494 × 10 −10 g/(s·m·Pa), respectively. This result is attributed to the formation of a new tight network structure that formed by RCE, ASKG, ACNF and glycerol [51]. The developed intelligent films retained excellent oxygen and water vapor barrier properties.

Oxygen and Water Vapor Permeabilities
Polymers 2020, 12, x FOR PEER REVIEW 12 of 19 Figure 11. Effect of the RCE amount on oxygen barrier and water vapor barrier properties of intelligent films. Figure 12 shows that the light transmission of the intelligent films decreased from 49.96% to 36.75% with an increase in RCE from 0% to 15% (at 600 nm), owing to the RCE, broke the ordered arrangement of ASKG and ACNF molecular chains, so that the light scattering and refraction increased. The entangled structure of the ACNF also increased the light scattering and reflection. The intelligent films showed UV light shielding effects when the amount of RCE added exceeded 5%, which indicates that the AFR10 and AFR15 films could reduce food spoilage that is caused by UV light.  Figure 13 shows the water-contact-angle data of the ASKG/ACNF/RCE and ASKG/CMC·Na/RCE intelligent films. It shows that the contact angle of the AFR0 film was 102°, which indicates a low water sensitivity, owing to the excessively tight network structure of the AFR0 film and the hydrophobic properties of the ACNF. An increase of RCE resulted in a decrease of contact angle. However, the contact angle remained at 93.25° when the amount of RCE added reached 15%, which indicates a low water sensitivity. These results were attributed to the RCE addition that broke the tight structure that formed among the ASKG, ACNF and glycerol, and promoted water Figure 11. Effect of the RCE amount on oxygen barrier and water vapor barrier properties of intelligent films. Figure 12 shows that the light transmission of the intelligent films decreased from 49.96% to 36.75% with an increase in RCE from 0% to 15% (at 600 nm), owing to the RCE, broke the ordered arrangement of ASKG and ACNF molecular chains, so that the light scattering and refraction increased. The entangled structure of the ACNF also increased the light scattering and reflection. The intelligent films showed UV light shielding effects when the amount of RCE added exceeded 5%, which indicates that the AFR10 and AFR15 films could reduce food spoilage that is caused by UV light.

Light Transmission of Intelligent Films
Polymers 2020, 12, x FOR PEER REVIEW 12 of 19 Figure 11. Effect of the RCE amount on oxygen barrier and water vapor barrier properties of intelligent films. Figure 12 shows that the light transmission of the intelligent films decreased from 49.96% to 36.75% with an increase in RCE from 0% to 15% (at 600 nm), owing to the RCE, broke the ordered arrangement of ASKG and ACNF molecular chains, so that the light scattering and refraction increased. The entangled structure of the ACNF also increased the light scattering and reflection. The intelligent films showed UV light shielding effects when the amount of RCE added exceeded 5%, which indicates that the AFR10 and AFR15 films could reduce food spoilage that is caused by UV light.  Figure 13 shows the water-contact-angle data of the ASKG/ACNF/RCE and ASKG/CMC·Na/RCE intelligent films. It shows that the contact angle of the AFR0 film was 102°, which indicates a low water sensitivity, owing to the excessively tight network structure of the AFR0 film and the hydrophobic properties of the ACNF. An increase of RCE resulted in a decrease of contact angle. However, the contact angle remained at 93.25° when the amount of RCE added reached 15%, which indicates a low water sensitivity. These results were attributed to the RCE addition that broke the tight structure that formed among the ASKG, ACNF and glycerol, and promoted water  Figure 13 shows the water-contact-angle data of the ASKG/ACNF/RCE and ASKG/CMC·Na/RCE intelligent films. It shows that the contact angle of the AFR0 film was 102 • , which indicates a low water sensitivity, owing to the excessively tight network structure of the AFR0 film and the hydrophobic properties of the ACNF. An increase of RCE resulted in a decrease of contact angle. However, the contact angle remained at 93.25 • when the amount of RCE added reached 15%, which indicates a low water sensitivity. These results were attributed to the RCE addition that broke the tight structure that formed among the ASKG, ACNF and glycerol, and promoted water penetration. When compared with the ASKG/CMC·Na/RCE intelligent films in our previous work [25], the contact angle of films that contained ACNF were higher than those that contained CMC·Na, which made them suitable for use under higher humidity conditions. Polymers 2020, 12, x FOR PEER REVIEW 13 of 19 penetration. When compared with the ASKG/CMC·Na/RCE intelligent films in our previous work [25], the contact angle of films that contained ACNF were higher than those that contained CMC·Na, which made them suitable for use under higher humidity conditions. Figure 13. Effect of the RCE amount on water contact angle of ASKG/ACNF/RCE intelligent films and ASKG/CMC·Na/RCE intelligent films.

Release Analysis
The release test that was based on the AFR15 film was conducted for evaluating the locking effects between the ACNF and RCE. Figure 14 shows that a maximum absorbance of the RCE solution could be observed at 538 nm, with a value of 0.089. The maximum absorbance of the 75% and 100% ethanol filtrates were 0 and the two filtrates were colorless after intelligent film immersion and oscillation for 12 h, which indicates that the RCE was locked in the ACF15 film. The same result was obtained for the AFR5 and AFR10 films.

Chroma-Response in Buffer Solution
The intelligent film was dark-reddish-purple, grayish-purple, dark-brown, atropurpureus, and yellowish-green at a pH of 3.0, 4.0-6.0, 7.0, 8.0-9.0, and 10.0 in Table 2, respectively. With an increase Figure 13. Effect of the RCE amount on water contact angle of ASKG/ACNF/RCE intelligent films and ASKG/CMC·Na/RCE intelligent films.

Release Analysis
The release test that was based on the AFR15 film was conducted for evaluating the locking effects between the ACNF and RCE. Figure 14 shows that a maximum absorbance of the RCE solution could be observed at 538 nm, with a value of 0.089. The maximum absorbance of the 75% and 100% ethanol filtrates were 0 and the two filtrates were colorless after intelligent film immersion and oscillation for 12 h, which indicates that the RCE was locked in the ACF15 film. The same result was obtained for the AFR5 and AFR10 films. penetration. When compared with the ASKG/CMC·Na/RCE intelligent films in our previous work [25], the contact angle of films that contained ACNF were higher than those that contained CMC·Na, which made them suitable for use under higher humidity conditions. Figure 13. Effect of the RCE amount on water contact angle of ASKG/ACNF/RCE intelligent films and ASKG/CMC·Na/RCE intelligent films.

Release Analysis
The release test that was based on the AFR15 film was conducted for evaluating the locking effects between the ACNF and RCE. Figure 14 shows that a maximum absorbance of the RCE solution could be observed at 538 nm, with a value of 0.089. The maximum absorbance of the 75% and 100% ethanol filtrates were 0 and the two filtrates were colorless after intelligent film immersion and oscillation for 12 h, which indicates that the RCE was locked in the ACF15 film. The same result was obtained for the AFR5 and AFR10 films.

Chroma-Response in Buffer Solution
The intelligent film was dark-reddish-purple, grayish-purple, dark-brown, atropurpureus, and yellowish-green at a pH of 3.0, 4.0-6.0, 7.0, 8.0-9.0, and 10.0 in Table 2, respectively. With an increase  The intelligent film was dark-reddish-purple, grayish-purple, dark-brown, atropurpureus, and yellowish-green at a pH of 3.0, 4.0-6.0, 7.0, 8.0-9.0, and 10.0 in Table 2, respectively. With an increase in pH from 3.0 to 6.0, the a* value decreased, but the b* value showed the opposite trend, owing to an increase in the pseudo-base carbinol structure of the RCE. When the pH increased to 7.0, the a* and b* values decreased further, owing to the change in RCE structure from pseudo-base carbinol to the anionic form. A further increase in pH to 10.0 resulted in a decrease of the a* value to negative and an increase in the b* value, because the change in RCE structure to chalcone [52]. The ∆E values of the AFR10 and AFR15 films exceeded 5, which indicates that the color differences could be observed by the eye [53]. in pH from 3.0 to 6.0, the a* value decreased, but the b* value showed the opposite trend, owing to an increase in the pseudo-base carbinol structure of the RCE. When the pH increased to 7.0, the a* and b* values decreased further, owing to the change in RCE structure from pseudo-base carbinol to the anionic form. A further increase in pH to 10.0 resulted in a decrease of the a* value to negative and an increase in the b* value, because the change in RCE structure to chalcone [52]. The ΔE values of the AFR10 and AFR15 films exceeded 5, which indicates that the color differences could be observed by the eye [53]. in pH from 3.0 to 6.0, the a* value decreased, but the b* value showed the opposite trend, owing to an increase in the pseudo-base carbinol structure of the RCE. When the pH increased to 7.0, the a* and b* values decreased further, owing to the change in RCE structure from pseudo-base carbinol to the anionic form. A further increase in pH to 10.0 resulted in a decrease of the a* value to negative and an increase in the b* value, because the change in RCE structure to chalcone [52]. The ΔE values of the AFR10 and AFR15 films exceeded 5, which indicates that the color differences could be observed by the eye [53]. in pH from 3.0 to 6.0, the a* value decreased, but the b* value showed the opposite trend, owing to an increase in the pseudo-base carbinol structure of the RCE. When the pH increased to 7.0, the a* and b* values decreased further, owing to the change in RCE structure from pseudo-base carbinol to the anionic form. A further increase in pH to 10.0 resulted in a decrease of the a* value to negative and an increase in the b* value, because the change in RCE structure to chalcone [52]. The ΔE values of the AFR10 and AFR15 films exceeded 5, which indicates that the color differences could be observed by the eye [53]. in pH from 3.0 to 6.0, the a* value decreased, but the b* value showed the opposite trend, owing to an increase in the pseudo-base carbinol structure of the RCE. When the pH increased to 7.0, the a* and b* values decreased further, owing to the change in RCE structure from pseudo-base carbinol to the anionic form. A further increase in pH to 10.0 resulted in a decrease of the a* value to negative and an increase in the b* value, because the change in RCE structure to chalcone [52]. The ΔE values of the AFR10 and AFR15 films exceeded 5, which indicates that the color differences could be observed by the eye [53]. in pH from 3.0 to 6.0, the a* value decreased, but the b* value showed the opposite trend, owing to an increase in the pseudo-base carbinol structure of the RCE. When the pH increased to 7.0, the a* and b* values decreased further, owing to the change in RCE structure from pseudo-base carbinol to the anionic form. A further increase in pH to 10.0 resulted in a decrease of the a* value to negative and an increase in the b* value, because the change in RCE structure to chalcone [52]. The ΔE values of the AFR10 and AFR15 films exceeded 5, which indicates that the color differences could be observed by the eye [53]. in pH from 3.0 to 6.0, the a* value decreased, but the b* value showed the opposite trend, owing to an increase in the pseudo-base carbinol structure of the RCE. When the pH increased to 7.0, the a* and b* values decreased further, owing to the change in RCE structure from pseudo-base carbinol to the anionic form. A further increase in pH to 10.0 resulted in a decrease of the a* value to negative and an increase in the b* value, because the change in RCE structure to chalcone [52]. The ΔE values of the AFR10 and AFR15 films exceeded 5, which indicates that the color differences could be observed by the eye [53]. in pH from 3.0 to 6.0, the a* value decreased, but the b* value showed the opposite trend, owing to an increase in the pseudo-base carbinol structure of the RCE. When the pH increased to 7.0, the a* and b* values decreased further, owing to the change in RCE structure from pseudo-base carbinol to the anionic form. A further increase in pH to 10.0 resulted in a decrease of the a* value to negative and an increase in the b* value, because the change in RCE structure to chalcone [52]. The ΔE values of the AFR10 and AFR15 films exceeded 5, which indicates that the color differences could be observed by the eye [53]. in pH from 3.0 to 6.0, the a* value decreased, but the b* value showed the opposite trend, owing to an increase in the pseudo-base carbinol structure of the RCE. When the pH increased to 7.0, the a* and b* values decreased further, owing to the change in RCE structure from pseudo-base carbinol to the anionic form. A further increase in pH to 10.0 resulted in a decrease of the a* value to negative and an increase in the b* value, because the change in RCE structure to chalcone [52]. The ΔE values of the AFR10 and AFR15 films exceeded 5, which indicates that the color differences could be observed by the eye [53]. in pH from 3.0 to 6.0, the a* value decreased, but the b* value showed the opposite trend, owing to an increase in the pseudo-base carbinol structure of the RCE. When the pH increased to 7.0, the a* and b* values decreased further, owing to the change in RCE structure from pseudo-base carbinol to the anionic form. A further increase in pH to 10.0 resulted in a decrease of the a* value to negative and an increase in the b* value, because the change in RCE structure to chalcone [52]. The ΔE values of the AFR10 and AFR15 films exceeded 5, which indicates that the color differences could be observed by the eye [53]. in pH from 3.0 to 6.0, the a* value decreased, but the b* value showed the opposite trend, owing to an increase in the pseudo-base carbinol structure of the RCE. When the pH increased to 7.0, the a* and b* values decreased further, owing to the change in RCE structure from pseudo-base carbinol to the anionic form. A further increase in pH to 10.0 resulted in a decrease of the a* value to negative and an increase in the b* value, because the change in RCE structure to chalcone [52]. The ΔE values of the AFR10 and AFR15 films exceeded 5, which indicates that the color differences could be observed by the eye [53]. in pH from 3.0 to 6.0, the a* value decreased, but the b* value showed the opposite trend, owing to an increase in the pseudo-base carbinol structure of the RCE. When the pH increased to 7.0, the a* and b* values decreased further, owing to the change in RCE structure from pseudo-base carbinol to the anionic form. A further increase in pH to 10.0 resulted in a decrease of the a* value to negative and an increase in the b* value, because the change in RCE structure to chalcone [52]. The ΔE values of the AFR10 and AFR15 films exceeded 5, which indicates that the color differences could be observed by the eye [53]. in pH from 3.0 to 6.0, the a* value decreased, but the b* value showed the opposite trend, owing to an increase in the pseudo-base carbinol structure of the RCE. When the pH increased to 7.0, the a* and b* values decreased further, owing to the change in RCE structure from pseudo-base carbinol to the anionic form. A further increase in pH to 10.0 resulted in a decrease of the a* value to negative and an increase in the b* value, because the change in RCE structure to chalcone [52]. The ΔE values of the AFR10 and AFR15 films exceeded 5, which indicates that the color differences could be observed by the eye [53]. in pH from 3.0 to 6.0, the a* value decreased, but the b* value showed the opposite trend, owing to an increase in the pseudo-base carbinol structure of the RCE. When the pH increased to 7.0, the a* and b* values decreased further, owing to the change in RCE structure from pseudo-base carbinol to the anionic form. A further increase in pH to 10.0 resulted in a decrease of the a* value to negative and an increase in the b* value, because the change in RCE structure to chalcone [52]. The ΔE values of the AFR10 and AFR15 films exceeded 5, which indicates that the color differences could be observed by the eye [53]. in pH from 3.0 to 6.0, the a* value decreased, but the b* value showed the opposite trend, owing to an increase in the pseudo-base carbinol structure of the RCE. When the pH increased to 7.0, the a* and b* values decreased further, owing to the change in RCE structure from pseudo-base carbinol to the anionic form. A further increase in pH to 10.0 resulted in a decrease of the a* value to negative and an increase in the b* value, because the change in RCE structure to chalcone [52]. The ΔE values of the AFR10 and AFR15 films exceeded 5, which indicates that the color differences could be observed by the eye [53]. in pH from 3.0 to 6.0, the a* value decreased, but the b* value showed the opposite trend, owing to an increase in the pseudo-base carbinol structure of the RCE. When the pH increased to 7.0, the a* and b* values decreased further, owing to the change in RCE structure from pseudo-base carbinol to the anionic form. A further increase in pH to 10.0 resulted in a decrease of the a* value to negative and an increase in the b* value, because the change in RCE structure to chalcone [52]. The ΔE values of the AFR10 and AFR15 films exceeded 5, which indicates that the color differences could be observed by the eye [53]. in pH from 3.0 to 6.0, the a* value decreased, but the b* value showed the opposite trend, owing to an increase in the pseudo-base carbinol structure of the RCE. When the pH increased to 7.0, the a* and b* values decreased further, owing to the change in RCE structure from pseudo-base carbinol to the anionic form. A further increase in pH to 10.0 resulted in a decrease of the a* value to negative and an increase in the b* value, because the change in RCE structure to chalcone [52]. The ΔE values of the AFR10 and AFR15 films exceeded 5, which indicates that the color differences could be observed by the eye [53]. in pH from 3.0 to 6.0, the a* value decreased, but the b* value showed the opposite trend, owing to an increase in the pseudo-base carbinol structure of the RCE. When the pH increased to 7.0, the a* and b* values decreased further, owing to the change in RCE structure from pseudo-base carbinol to the anionic form. A further increase in pH to 10.0 resulted in a decrease of the a* value to negative and an increase in the b* value, because the change in RCE structure to chalcone [52]. The ΔE values of the AFR10 and AFR15 films exceeded 5, which indicates that the color differences could be observed by the eye [53]. in pH from 3.0 to 6.0, the a* value decreased, but the b* value showed the opposite trend, owing to an increase in the pseudo-base carbinol structure of the RCE. When the pH increased to 7.0, the a* and b* values decreased further, owing to the change in RCE structure from pseudo-base carbinol to the anionic form. A further increase in pH to 10.0 resulted in a decrease of the a* value to negative and an increase in the b* value, because the change in RCE structure to chalcone [52]. The ΔE values of the AFR10 and AFR15 films exceeded 5, which indicates that the color differences could be observed by the eye [53]. in pH from 3.0 to 6.0, the a* value decreased, but the b* value showed the opposite trend, owing to an increase in the pseudo-base carbinol structure of the RCE. When the pH increased to 7.0, the a* and b* values decreased further, owing to the change in RCE structure from pseudo-base carbinol to the anionic form. A further increase in pH to 10.0 resulted in a decrease of the a* value to negative and an increase in the b* value, because the change in RCE structure to chalcone [52]. The ΔE values of the AFR10 and AFR15 films exceeded 5, which indicates that the color differences could be observed by the eye [53]. in pH from 3.0 to 6.0, the a* value decreased, but the b* value showed the opposite trend, owing to an increase in the pseudo-base carbinol structure of the RCE. When the pH increased to 7.0, the a* and b* values decreased further, owing to the change in RCE structure from pseudo-base carbinol to the anionic form. A further increase in pH to 10.0 resulted in a decrease of the a* value to negative and an increase in the b* value, because the change in RCE structure to chalcone [52]. The ΔE values of the AFR10 and AFR15 films exceeded 5, which indicates that the color differences could be observed by the eye [53]. in pH from 3.0 to 6.0, the a* value decreased, but the b* value showed the opposite trend, owing to an increase in the pseudo-base carbinol structure of the RCE. When the pH increased to 7.0, the a* and b* values decreased further, owing to the change in RCE structure from pseudo-base carbinol to the anionic form. A further increase in pH to 10.0 resulted in a decrease of the a* value to negative and an increase in the b* value, because the change in RCE structure to chalcone [52]. The ΔE values of the AFR10 and AFR15 films exceeded 5, which indicates that the color differences could be observed by the eye [53]. in pH from 3.0 to 6.0, the a* value decreased, but the b* value showed the opposite trend, owing to an increase in the pseudo-base carbinol structure of the RCE. When the pH increased to 7.0, the a* and b* values decreased further, owing to the change in RCE structure from pseudo-base carbinol to the anionic form. A further increase in pH to 10.0 resulted in a decrease of the a* value to negative and an increase in the b* value, because the change in RCE structure to chalcone [52]. The ΔE values of the AFR10 and AFR15 films exceeded 5, which indicates that the color differences could be observed by the eye [53]. in pH from 3.0 to 6.0, the a* value decreased, but the b* value showed the opposite trend, owing to an increase in the pseudo-base carbinol structure of the RCE. When the pH increased to 7.0, the a* and b* values decreased further, owing to the change in RCE structure from pseudo-base carbinol to the anionic form. A further increase in pH to 10.0 resulted in a decrease of the a* value to negative and an increase in the b* value, because the change in RCE structure to chalcone [52]. The ΔE values of the AFR10 and AFR15 films exceeded 5, which indicates that the color differences could be observed by the eye [53]. in pH from 3.0 to 6.0, the a* value decreased, but the b* value showed the opposite trend, owing to an increase in the pseudo-base carbinol structure of the RCE. When the pH increased to 7.0, the a* and b* values decreased further, owing to the change in RCE structure from pseudo-base carbinol to the anionic form. A further increase in pH to 10.0 resulted in a decrease of the a* value to negative and an increase in the b* value, because the change in RCE structure to chalcone [52]. The ΔE values of the AFR10 and AFR15 films exceeded 5, which indicates that the color differences could be observed by the eye [53]. in pH from 3.0 to 6.0, the a* value decreased, but the b* value showed the opposite trend, owing to an increase in the pseudo-base carbinol structure of the RCE. When the pH increased to 7.0, the a* and b* values decreased further, owing to the change in RCE structure from pseudo-base carbinol to the anionic form. A further increase in pH to 10.0 resulted in a decrease of the a* value to negative and an increase in the b* value, because the change in RCE structure to chalcone [52]. The ΔE values of the AFR10 and AFR15 films exceeded 5, which indicates that the color differences could be observed by the eye [53]. in pH from 3.0 to 6.0, the a* value decreased, but the b* value showed the opposite trend, owing to an increase in the pseudo-base carbinol structure of the RCE. When the pH increased to 7.0, the a* and b* values decreased further, owing to the change in RCE structure from pseudo-base carbinol to the anionic form. A further increase in pH to 10.0 resulted in a decrease of the a* value to negative and an increase in the b* value, because the change in RCE structure to chalcone [52]. The ΔE values of the AFR10 and AFR15 films exceeded 5, which indicates that the color differences could be observed by the eye [53]. in pH from 3.0 to 6.0, the a* value decreased, but the b* value showed the opposite trend, owing to an increase in the pseudo-base carbinol structure of the RCE. When the pH increased to 7.0, the a* and b* values decreased further, owing to the change in RCE structure from pseudo-base carbinol to the anionic form. A further increase in pH to 10.0 resulted in a decrease of the a* value to negative and an increase in the b* value, because the change in RCE structure to chalcone [52]. The ΔE values of the AFR10 and AFR15 films exceeded 5, which indicates that the color differences could be observed by the eye [53]. in pH from 3.0 to 6.0, the a* value decreased, but the b* value showed the opposite trend, owing to an increase in the pseudo-base carbinol structure of the RCE. When the pH increased to 7.0, the a* and b* values decreased further, owing to the change in RCE structure from pseudo-base carbinol to the anionic form. A further increase in pH to 10.0 resulted in a decrease of the a* value to negative and an increase in the b* value, because the change in RCE structure to chalcone [52]. The ΔE values of the AFR10 and AFR15 films exceeded 5, which indicates that the color differences could be observed by the eye [53]. in pH from 3.0 to 6.0, the a* value decreased, but the b* value showed the opposite trend, owing to an increase in the pseudo-base carbinol structure of the RCE. When the pH increased to 7.0, the a* and b* values decreased further, owing to the change in RCE structure from pseudo-base carbinol to the anionic form. A further increase in pH to 10.0 resulted in a decrease of the a* value to negative and an increase in the b* value, because the change in RCE structure to chalcone [52]. The ΔE values of the AFR10 and AFR15 films exceeded 5, which indicates that the color differences could be observed by the eye [53]. in pH from 3.0 to 6.0, the a* value decreased, but the b* value showed the opposite trend, owing to an increase in the pseudo-base carbinol structure of the RCE. When the pH increased to 7.0, the a* and b* values decreased further, owing to the change in RCE structure from pseudo-base carbinol to the anionic form. A further increase in pH to 10.0 resulted in a decrease of the a* value to negative and an increase in the b* value, because the change in RCE structure to chalcone [52]. The ΔE values of the AFR10 and AFR15 films exceeded 5, which indicates that the color differences could be observed by the eye [53]. in pH from 3.0 to 6.0, the a* value decreased, but the b* value showed the opposite trend, owing to an increase in the pseudo-base carbinol structure of the RCE. When the pH increased to 7.0, the a* and b* values decreased further, owing to the change in RCE structure from pseudo-base carbinol to the anionic form. A further increase in pH to 10.0 resulted in a decrease of the a* value to negative and an increase in the b* value, because the change in RCE structure to chalcone [52]. The ΔE values of the AFR10 and AFR15 films exceeded 5, which indicates that the color differences could be observed by the eye [53]. in pH from 3.0 to 6.0, the a* value decreased, but the b* value showed the opposite trend, owing to an increase in the pseudo-base carbinol structure of the RCE. When the pH increased to 7.0, the a* and b* values decreased further, owing to the change in RCE structure from pseudo-base carbinol to the anionic form. A further increase in pH to 10.0 resulted in a decrease of the a* value to negative and an increase in the b* value, because the change in RCE structure to chalcone [52]. The ΔE values of the AFR10 and AFR15 films exceeded 5, which indicates that the color differences could be observed by the eye [53]. in pH from 3.0 to 6.0, the a* value decreased, but the b* value showed the opposite trend, owing to an increase in the pseudo-base carbinol structure of the RCE. When the pH increased to 7.0, the a* and b* values decreased further, owing to the change in RCE structure from pseudo-base carbinol to the anionic form. A further increase in pH to 10.0 resulted in a decrease of the a* value to negative and an increase in the b* value, because the change in RCE structure to chalcone [52]. The ΔE values of the AFR10 and AFR15 films exceeded 5, which indicates that the color differences could be observed by the eye [53]. in pH from 3.0 to 6.0, the a* value decreased, but the b* value showed the opposite trend, owing to an increase in the pseudo-base carbinol structure of the RCE. When the pH increased to 7.0, the a* and b* values decreased further, owing to the change in RCE structure from pseudo-base carbinol to the anionic form. A further increase in pH to 10.0 resulted in a decrease of the a* value to negative and an increase in the b* value, because the change in RCE structure to chalcone [52]. The ΔE values of the AFR10 and AFR15 films exceeded 5, which indicates that the color differences could be observed by the eye [53]. in pH from 3.0 to 6.0, the a* value decreased, but the b* value showed the opposite trend, owing to an increase in the pseudo-base carbinol structure of the RCE. When the pH increased to 7.0, the a* and b* values decreased further, owing to the change in RCE structure from pseudo-base carbinol to the anionic form. A further increase in pH to 10.0 resulted in a decrease of the a* value to negative and an increase in the b* value, because the change in RCE structure to chalcone [52]. The ΔE values of the AFR10 and AFR15 films exceeded 5, which indicates that the color differences could be observed by the eye [53]. in pH from 3.0 to 6.0, the a* value decreased, but the b* value showed the opposite trend, owing to an increase in the pseudo-base carbinol structure of the RCE. When the pH increased to 7.0, the a* and b* values decreased further, owing to the change in RCE structure from pseudo-base carbinol to the anionic form. A further increase in pH to 10.0 resulted in a decrease of the a* value to negative and an increase in the b* value, because the change in RCE structure to chalcone [52]. The ΔE values of the AFR10 and AFR15 films exceeded 5, which indicates that the color differences could be observed by the eye [53]. in pH from 3.0 to 6.0, the a* value decreased, but the b* value showed the opposite trend, owing to an increase in the pseudo-base carbinol structure of the RCE. When the pH increased to 7.0, the a* and b* values decreased further, owing to the change in RCE structure from pseudo-base carbinol to the anionic form. A further increase in pH to 10.0 resulted in a decrease of the a* value to negative and an increase in the b* value, because the change in RCE structure to chalcone [52]. The ΔE values of the AFR10 and AFR15 films exceeded 5, which indicates that the color differences could be observed by the eye [53]. in pH from 3.0 to 6.0, the a* value decreased, but the b* value showed the opposite trend, owing to an increase in the pseudo-base carbinol structure of the RCE. When the pH increased to 7.0, the a* and b* values decreased further, owing to the change in RCE structure from pseudo-base carbinol to the anionic form. A further increase in pH to 10.0 resulted in a decrease of the a* value to negative and an increase in the b* value, because the change in RCE structure to chalcone [52]. The ΔE values of the AFR10 and AFR15 films exceeded 5, which indicates that the color differences could be observed by the eye [53]. in pH from 3.0 to 6.0, the a* value decreased, but the b* value showed the opposite trend, owing to an increase in the pseudo-base carbinol structure of the RCE. When the pH increased to 7.0, the a* and b* values decreased further, owing to the change in RCE structure from pseudo-base carbinol to the anionic form. A further increase in pH to 10.0 resulted in a decrease of the a* value to negative and an increase in the b* value, because the change in RCE structure to chalcone [52]. The ΔE values of the AFR10 and AFR15 films exceeded 5, which indicates that the color differences could be observed by the eye [53]. in pH from 3.0 to 6.0, the a* value decreased, but the b* value showed the opposite trend, owing to an increase in the pseudo-base carbinol structure of the RCE. When the pH increased to 7.0, the a* and b* values decreased further, owing to the change in RCE structure from pseudo-base carbinol to the anionic form. A further increase in pH to 10.0 resulted in a decrease of the a* value to negative and an increase in the b* value, because the change in RCE structure to chalcone [52]. The ΔE values of the AFR10 and AFR15 films exceeded 5, which indicates that the color differences could be observed by the eye [53]. in pH from 3.0 to 6.0, the a* value decreased, but the b* value showed the opposite trend, owing to an increase in the pseudo-base carbinol structure of the RCE. When the pH increased to 7.0, the a* and b* values decreased further, owing to the change in RCE structure from pseudo-base carbinol to the anionic form. A further increase in pH to 10.0 resulted in a decrease of the a* value to negative and an increase in the b* value, because the change in RCE structure to chalcone [52]. The ΔE values of the AFR10 and AFR15 films exceeded 5, which indicates that the color differences could be observed by the eye [53]. in pH from 3.0 to 6.0, the a* value decreased, but the b* value showed the opposite trend, owing to an increase in the pseudo-base carbinol structure of the RCE. When the pH increased to 7.0, the a* and b* values decreased further, owing to the change in RCE structure from pseudo-base carbinol to the anionic form. A further increase in pH to 10.0 resulted in a decrease of the a* value to negative and an increase in the b* value, because the change in RCE structure to chalcone [52]. The ΔE values of the AFR10 and AFR15 films exceeded 5, which indicates that the color differences could be observed by the eye [53]. in pH from 3.0 to 6.0, the a* value decreased, but the b* value showed the opposite trend, owing to an increase in the pseudo-base carbinol structure of the RCE. When the pH increased to 7.0, the a* and b* values decreased further, owing to the change in RCE structure from pseudo-base carbinol to the anionic form. A further increase in pH to 10.0 resulted in a decrease of the a* value to negative and an increase in the b* value, because the change in RCE structure to chalcone [52]. The ΔE values of the AFR10 and AFR15 films exceeded 5, which indicates that the color differences could be observed by the eye [53]. in pH from 3.0 to 6.0, the a* value decreased, but the b* value showed the opposite trend, owing to an increase in the pseudo-base carbinol structure of the RCE. When the pH increased to 7.0, the a* and b* values decreased further, owing to the change in RCE structure from pseudo-base carbinol to the anionic form. A further increase in pH to 10.0 resulted in a decrease of the a* value to negative and an increase in the b* value, because the change in RCE structure to chalcone [52]. The ΔE values of the AFR10 and AFR15 films exceeded 5, which indicates that the color differences could be observed by the eye [53]. in pH from 3.0 to 6.0, the a* value decreased, but the b* value showed the opposite trend, owing to an increase in the pseudo-base carbinol structure of the RCE. When the pH increased to 7.0, the a* and b* values decreased further, owing to the change in RCE structure from pseudo-base carbinol to the anionic form. A further increase in pH to 10.0 resulted in a decrease of the a* value to negative and an increase in the b* value, because the change in RCE structure to chalcone [52]. The ΔE values of the AFR10 and AFR15 films exceeded 5, which indicates that the color differences could be observed by the eye [53]. in pH from 3.0 to 6.0, the a* value decreased, but the b* value showed the opposite trend, owing to an increase in the pseudo-base carbinol structure of the RCE. When the pH increased to 7.0, the a* and b* values decreased further, owing to the change in RCE structure from pseudo-base carbinol to the anionic form. A further increase in pH to 10.0 resulted in a decrease of the a* value to negative and an increase in the b* value, because the change in RCE structure to chalcone [52]. The ΔE values of the AFR10 and AFR15 films exceeded 5, which indicates that the color differences could be observed by the eye [53]. a-f are the significant differences in the same parameters (p < 0.05).

Chroma-Response in NH 3 Condition
NH 3 was selected to simulate the TVB-N that is produced by seafood to evaluate the practical application of the ASKG/ACNF/RCE intelligent films. As shown in Table 3, the L* values decreased as the RCE addition and relative humidity increased, which indicates that the developed film became dark. After increasing the relative humidity to 75%, the a* and the b* values decreased, owing to the acceleration of the contact between RCE and OH − ions by the hydrophobic ACNF, which accelerated the structural change in RCE. NH3 was selected to simulate the TVB-N that is produced by seafood to evaluate the practical application of the ASKG/ACNF/RCE intelligent films. As shown in Table 3, the L* values decreased as the RCE addition and relative humidity increased, which indicates that the developed film became dark. After increasing the relative humidity to 75%, the a* and the b* values decreased, owing to the acceleration of the contact between RCE and OHions by the hydrophobic ACNF, which accelerated the structural change in RCE.
When compared with ASKG/CMC·Na/RCE intelligent films in our previous work [25], the color change was slightly different, owing to the scattering and reflection of light that was caused by the long fiber morphology of the ACNF.  Figure 15 shows changes in pH and TVB-N of the freshness shrimp, colorimetric parameters, and a photograph of the intelligent film and they are listed in Table 4. The pH and TVB-N of the fresh freshwater shrimp were 6.831 and 1.4047 mg/100 g, respectively. The intelligent film was dark purple. After 12 h, the two values increased to 7.163 and 20.0759 mg/100 g, respectively. Table 4 shows that the a* value decreased to negative, but the b* value showed opposite changes. The intelligent film was yellow-green. The pH of the freshwater shrimp changed to alkaline and spoilage occurred after 12 h according to GB 2733-2015 (a Chinese National Standard). A further increase in storage time showed a more obvious increase in the two values. These results are attributed to protein and amino acid decomposition in freshwater shrimp into volatile nitrogen under the action of microorganisms [54]. According to our study, ~0.01 g of intelligent film was suitable for detecting freshness information for 25 g of freshwater shrimp to consumers through a color change in real time.

Detecting Analysis of Intelligent Film for Freshwater Shrimp Freshness in Real Time
NH3 was selected to simulate the TVB-N that is produced by seafood to evaluate the practical application of the ASKG/ACNF/RCE intelligent films. As shown in Table 3, the L* values decreased as the RCE addition and relative humidity increased, which indicates that the developed film became dark. After increasing the relative humidity to 75%, the a* and the b* values decreased, owing to the acceleration of the contact between RCE and OHions by the hydrophobic ACNF, which accelerated the structural change in RCE.
When compared with ASKG/CMC·Na/RCE intelligent films in our previous work [25], the color change was slightly different, owing to the scattering and reflection of light that was caused by the long fiber morphology of the ACNF.  Figure 15 shows changes in pH and TVB-N of the freshness shrimp, colorimetric parameters, and a photograph of the intelligent film and they are listed in Table 4. The pH and TVB-N of the fresh freshwater shrimp were 6.831 and 1.4047 mg/100 g, respectively. The intelligent film was dark purple. After 12 h, the two values increased to 7.163 and 20.0759 mg/100 g, respectively. Table 4 shows that the a* value decreased to negative, but the b* value showed opposite changes. The intelligent film was yellow-green. The pH of the freshwater shrimp changed to alkaline and spoilage occurred after 12 h according to GB 2733-2015 (a Chinese National Standard). A further increase in storage time showed a more obvious increase in the two values. These results are attributed to protein and amino acid decomposition in freshwater shrimp into volatile nitrogen under the action of microorganisms [54]. According to our study, ~0.01 g of intelligent film was suitable for detecting freshness information for 25 g of freshwater shrimp to consumers through a color change in real time.

75%
78.92 ± 0.08 b −6.09 ± 0.12 b 11.87 ± 0.22 b 14.82 ± 0.19 b NH3 was selected to simulate the TVB-N that is produced by seafood to evaluate the practical application of the ASKG/ACNF/RCE intelligent films. As shown in Table 3, the L* values decreased as the RCE addition and relative humidity increased, which indicates that the developed film became dark. After increasing the relative humidity to 75%, the a* and the b* values decreased, owing to the acceleration of the contact between RCE and OHions by the hydrophobic ACNF, which accelerated the structural change in RCE.
When compared with ASKG/CMC·Na/RCE intelligent films in our previous work [25], the color change was slightly different, owing to the scattering and reflection of light that was caused by the long fiber morphology of the ACNF.  Figure 15 shows changes in pH and TVB-N of the freshness shrimp, colorimetric parameters, and a photograph of the intelligent film and they are listed in Table 4. The pH and TVB-N of the fresh freshwater shrimp were 6.831 and 1.4047 mg/100 g, respectively. The intelligent film was dark purple. After 12 h, the two values increased to 7.163 and 20.0759 mg/100 g, respectively. Table 4 shows that the a* value decreased to negative, but the b* value showed opposite changes. The intelligent film was yellow-green. The pH of the freshwater shrimp changed to alkaline and spoilage occurred after 12 h according to GB 2733-2015 (a Chinese National Standard). A further increase in storage time showed a more obvious increase in the two values. These results are attributed to protein and amino acid decomposition in freshwater shrimp into volatile nitrogen under the action of microorganisms [54]. According to our study, ~0.01 g of intelligent film was suitable for detecting freshness information for 25 g of freshwater shrimp to consumers through a color change in real time.

Detecting Analysis of Intelligent Film for Freshwater Shrimp Freshness in Real Time
NH3 was selected to simulate the TVB-N that is produced by seafood to evaluate the practical application of the ASKG/ACNF/RCE intelligent films. As shown in Table 3, the L* values decreased as the RCE addition and relative humidity increased, which indicates that the developed film became dark. After increasing the relative humidity to 75%, the a* and the b* values decreased, owing to the acceleration of the contact between RCE and OHions by the hydrophobic ACNF, which accelerated the structural change in RCE.
When compared with ASKG/CMC·Na/RCE intelligent films in our previous work [25], the color change was slightly different, owing to the scattering and reflection of light that was caused by the long fiber morphology of the ACNF.  Figure 15 shows changes in pH and TVB-N of the freshness shrimp, colorimetric parameters, and a photograph of the intelligent film and they are listed in Table 4. The pH and TVB-N of the fresh freshwater shrimp were 6.831 and 1.4047 mg/100 g, respectively. The intelligent film was dark purple. After 12 h, the two values increased to 7.163 and 20.0759 mg/100 g, respectively. Table 4 shows that the a* value decreased to negative, but the b* value showed opposite changes. The intelligent film was yellow-green. The pH of the freshwater shrimp changed to alkaline and spoilage occurred after 12 h according to GB 2733-2015 (a Chinese National Standard). A further increase in storage time showed a more obvious increase in the two values. These results are attributed to protein and amino acid decomposition in freshwater shrimp into volatile nitrogen under the action of microorganisms [54]. According to our study, ~0.01 g of intelligent film was suitable for detecting freshness information for 25 g of freshwater shrimp to consumers through a color change in real time.

90%
79.34 ± 0.25 b −0.11 ± 0.07 c 2.67 ± 0.32 a 4.66 ± 0.18 a NH3 was selected to simulate the TVB-N that is produced by seafood to evaluate the practical application of the ASKG/ACNF/RCE intelligent films. As shown in Table 3, the L* values decreased as the RCE addition and relative humidity increased, which indicates that the developed film became dark. After increasing the relative humidity to 75%, the a* and the b* values decreased, owing to the acceleration of the contact between RCE and OHions by the hydrophobic ACNF, which accelerated the structural change in RCE.
When compared with ASKG/CMC·Na/RCE intelligent films in our previous work [25], the color change was slightly different, owing to the scattering and reflection of light that was caused by the long fiber morphology of the ACNF.  Figure 15 shows changes in pH and TVB-N of the freshness shrimp, colorimetric parameters, and a photograph of the intelligent film and they are listed in Table 4. The pH and TVB-N of the fresh freshwater shrimp were 6.831 and 1.4047 mg/100 g, respectively. The intelligent film was dark purple. After 12 h, the two values increased to 7.163 and 20.0759 mg/100 g, respectively. Table 4 shows that the a* value decreased to negative, but the b* value showed opposite changes. The intelligent film was yellow-green. The pH of the freshwater shrimp changed to alkaline and spoilage occurred after 12 h according to GB 2733-2015 (a Chinese National Standard). A further increase in storage time showed a more obvious increase in the two values. These results are attributed to protein and amino acid decomposition in freshwater shrimp into volatile nitrogen under the action of microorganisms [54]. According to our study, ~0.01 g of intelligent film was suitable for detecting freshness information for 25 g of freshwater shrimp to consumers through a color change in real time.

Detecting Analysis of Intelligent Film for Freshwater Shrimp Freshness in Real Time
NH3 was selected to simulate the TVB-N that is produced by seafood to evaluate the practical application of the ASKG/ACNF/RCE intelligent films. As shown in Table 3, the L* values decreased as the RCE addition and relative humidity increased, which indicates that the developed film became dark. After increasing the relative humidity to 75%, the a* and the b* values decreased, owing to the acceleration of the contact between RCE and OHions by the hydrophobic ACNF, which accelerated the structural change in RCE.
When compared with ASKG/CMC·Na/RCE intelligent films in our previous work [25], the color change was slightly different, owing to the scattering and reflection of light that was caused by the long fiber morphology of the ACNF.  Figure 15 shows changes in pH and TVB-N of the freshness shrimp, colorimetric parameters, and a photograph of the intelligent film and they are listed in Table 4. The pH and TVB-N of the fresh freshwater shrimp were 6.831 and 1.4047 mg/100 g, respectively. The intelligent film was dark purple. After 12 h, the two values increased to 7.163 and 20.0759 mg/100 g, respectively. Table 4 shows that the a* value decreased to negative, but the b* value showed opposite changes. The intelligent film was yellow-green. The pH of the freshwater shrimp changed to alkaline and spoilage occurred after 12 h according to GB 2733-2015 (a Chinese National Standard). A further increase in storage time showed a more obvious increase in the two values. These results are attributed to protein and amino acid decomposition in freshwater shrimp into volatile nitrogen under the action of microorganisms [54]. According to our study, ~0.01 g of intelligent film was suitable for detecting freshness information for 25 g of freshwater shrimp to consumers through a color change in real time.

AFR10 33%
70.66 ± 0.44 a −7.22 ± 0.03 a 31.95 ± 0.81 c 25.02 ± 1.10 c NH3 was selected to simulate the TVB-N that is produced by seafood to evaluate the practical application of the ASKG/ACNF/RCE intelligent films. As shown in Table 3, the L* values decreased as the RCE addition and relative humidity increased, which indicates that the developed film became dark. After increasing the relative humidity to 75%, the a* and the b* values decreased, owing to the acceleration of the contact between RCE and OHions by the hydrophobic ACNF, which accelerated the structural change in RCE.
When compared with ASKG/CMC·Na/RCE intelligent films in our previous work [25], the color change was slightly different, owing to the scattering and reflection of light that was caused by the long fiber morphology of the ACNF.  Figure 15 shows changes in pH and TVB-N of the freshness shrimp, colorimetric parameters, and a photograph of the intelligent film and they are listed in Table 4. The pH and TVB-N of the fresh freshwater shrimp were 6.831 and 1.4047 mg/100 g, respectively. The intelligent film was dark purple. After 12 h, the two values increased to 7.163 and 20.0759 mg/100 g, respectively. Table 4 shows that the a* value decreased to negative, but the b* value showed opposite changes. The intelligent film was yellow-green. The pH of the freshwater shrimp changed to alkaline and spoilage occurred after 12 h according to GB 2733-2015 (a Chinese National Standard). A further increase in storage time showed a more obvious increase in the two values. These results are attributed to protein and amino acid decomposition in freshwater shrimp into volatile nitrogen under the action of microorganisms [54]. According to our study, ~0.01 g of intelligent film was suitable for detecting freshness information for 25 g of freshwater shrimp to consumers through a color change in real time.

Detecting Analysis of Intelligent Film for Freshwater Shrimp Freshness in Real Time
NH3 was selected to simulate the TVB-N that is produced by seafood to evaluate the practical application of the ASKG/ACNF/RCE intelligent films. As shown in Table 3, the L* values decreased as the RCE addition and relative humidity increased, which indicates that the developed film became dark. After increasing the relative humidity to 75%, the a* and the b* values decreased, owing to the acceleration of the contact between RCE and OHions by the hydrophobic ACNF, which accelerated the structural change in RCE.
When compared with ASKG/CMC·Na/RCE intelligent films in our previous work [25], the color change was slightly different, owing to the scattering and reflection of light that was caused by the long fiber morphology of the ACNF.  Figure 15 shows changes in pH and TVB-N of the freshness shrimp, colorimetric parameters, and a photograph of the intelligent film and they are listed in Table 4. The pH and TVB-N of the fresh freshwater shrimp were 6.831 and 1.4047 mg/100 g, respectively. The intelligent film was dark purple. After 12 h, the two values increased to 7.163 and 20.0759 mg/100 g, respectively. Table 4 shows that the a* value decreased to negative, but the b* value showed opposite changes. The intelligent film was yellow-green. The pH of the freshwater shrimp changed to alkaline and spoilage occurred after 12 h according to GB 2733-2015 (a Chinese National Standard). A further increase in storage time showed a more obvious increase in the two values. These results are attributed to protein and amino acid decomposition in freshwater shrimp into volatile nitrogen under the action of microorganisms [54]. According to our study, ~0.01 g of intelligent film was suitable for detecting freshness information for 25 g of freshwater shrimp to consumers through a color change in real time. NH3 was selected to simulate the TVB-N that is produced by seafood to evaluate the practical application of the ASKG/ACNF/RCE intelligent films. As shown in Table 3, the L* values decreased as the RCE addition and relative humidity increased, which indicates that the developed film became dark. After increasing the relative humidity to 75%, the a* and the b* values decreased, owing to the acceleration of the contact between RCE and OHions by the hydrophobic ACNF, which accelerated the structural change in RCE.

Detecting Analysis of Intelligent Film for Freshwater Shrimp Freshness in Real Time
When compared with ASKG/CMC·Na/RCE intelligent films in our previous work [25], the color change was slightly different, owing to the scattering and reflection of light that was caused by the long fiber morphology of the ACNF.  Figure 15 shows changes in pH and TVB-N of the freshness shrimp, colorimetric parameters, and a photograph of the intelligent film and they are listed in Table 4. The pH and TVB-N of the fresh freshwater shrimp were 6.831 and 1.4047 mg/100 g, respectively. The intelligent film was dark purple. After 12 h, the two values increased to 7.163 and 20.0759 mg/100 g, respectively. Table 4 shows that the a* value decreased to negative, but the b* value showed opposite changes. The intelligent film was yellow-green. The pH of the freshwater shrimp changed to alkaline and spoilage occurred after 12 h according to GB 2733-2015 (a Chinese National Standard). A further increase in storage time showed a more obvious increase in the two values. These results are attributed to protein and amino acid decomposition in freshwater shrimp into volatile nitrogen under the action of microorganisms [54]. According to our study, ~0.01 g of intelligent film was suitable for detecting freshness information for 25 g of freshwater shrimp to consumers through a color change in real time.

Detecting Analysis of Intelligent Film for Freshwater Shrimp Freshness in Real Time
NH3 was selected to simulate the TVB-N that is produced by seafood to evaluate the practical application of the ASKG/ACNF/RCE intelligent films. As shown in Table 3, the L* values decreased as the RCE addition and relative humidity increased, which indicates that the developed film became dark. After increasing the relative humidity to 75%, the a* and the b* values decreased, owing to the acceleration of the contact between RCE and OHions by the hydrophobic ACNF, which accelerated the structural change in RCE.
When compared with ASKG/CMC·Na/RCE intelligent films in our previous work [25], the color change was slightly different, owing to the scattering and reflection of light that was caused by the long fiber morphology of the ACNF.  Figure 15 shows changes in pH and TVB-N of the freshness shrimp, colorimetric parameters, and a photograph of the intelligent film and they are listed in Table 4. The pH and TVB-N of the fresh freshwater shrimp were 6.831 and 1.4047 mg/100 g, respectively. The intelligent film was dark purple. After 12 h, the two values increased to 7.163 and 20.0759 mg/100 g, respectively. Table 4 shows that the a* value decreased to negative, but the b* value showed opposite changes. The intelligent film was yellow-green. The pH of the freshwater shrimp changed to alkaline and spoilage occurred after 12 h according to GB 2733-2015 (a Chinese National Standard). A further increase in storage time showed a more obvious increase in the two values. These results are attributed to protein and amino acid decomposition in freshwater shrimp into volatile nitrogen under the action of microorganisms [54]. According to our study, ~0.01 g of intelligent film was suitable for detecting freshness information for 25 g of freshwater shrimp to consumers through a color change in real time.

90%
73.97 ± 0.55 c −2.25 ± 0.38 c 15.32 ± 1.24 a 10.89 ± 1.10 a NH3 was selected to simulate the TVB-N that is produced by seafood to evaluate the practical application of the ASKG/ACNF/RCE intelligent films. As shown in Table 3, the L* values decreased as the RCE addition and relative humidity increased, which indicates that the developed film became dark. After increasing the relative humidity to 75%, the a* and the b* values decreased, owing to the acceleration of the contact between RCE and OHions by the hydrophobic ACNF, which accelerated the structural change in RCE.
When compared with ASKG/CMC·Na/RCE intelligent films in our previous work [25], the color change was slightly different, owing to the scattering and reflection of light that was caused by the long fiber morphology of the ACNF.  Figure 15 shows changes in pH and TVB-N of the freshness shrimp, colorimetric parameters, and a photograph of the intelligent film and they are listed in Table 4. The pH and TVB-N of the fresh freshwater shrimp were 6.831 and 1.4047 mg/100 g, respectively. The intelligent film was dark purple. After 12 h, the two values increased to 7.163 and 20.0759 mg/100 g, respectively. Table 4 shows that the a* value decreased to negative, but the b* value showed opposite changes. The intelligent film was yellow-green. The pH of the freshwater shrimp changed to alkaline and spoilage occurred after 12 h according to GB 2733-2015 (a Chinese National Standard). A further increase in storage time showed a more obvious increase in the two values. These results are attributed to protein and amino acid decomposition in freshwater shrimp into volatile nitrogen under the action of microorganisms [54]. According to our study, ~0.01 g of intelligent film was suitable for detecting freshness information for 25 g of freshwater shrimp to consumers through a color change in real time.

Detecting Analysis of Intelligent Film for Freshwater Shrimp Freshness in Real Time
NH3 was selected to simulate the TVB-N that is produced by seafood to evaluate the practical application of the ASKG/ACNF/RCE intelligent films. As shown in Table 3, the L* values decreased as the RCE addition and relative humidity increased, which indicates that the developed film became dark. After increasing the relative humidity to 75%, the a* and the b* values decreased, owing to the acceleration of the contact between RCE and OHions by the hydrophobic ACNF, which accelerated the structural change in RCE.
When compared with ASKG/CMC·Na/RCE intelligent films in our previous work [25], the color change was slightly different, owing to the scattering and reflection of light that was caused by the long fiber morphology of the ACNF.  Figure 15 shows changes in pH and TVB-N of the freshness shrimp, colorimetric parameters, and a photograph of the intelligent film and they are listed in Table 4. The pH and TVB-N of the fresh freshwater shrimp were 6.831 and 1.4047 mg/100 g, respectively. The intelligent film was dark purple. After 12 h, the two values increased to 7.163 and 20.0759 mg/100 g, respectively. Table 4 shows that the a* value decreased to negative, but the b* value showed opposite changes. The intelligent film was yellow-green. The pH of the freshwater shrimp changed to alkaline and spoilage occurred after 12 h according to GB 2733-2015 (a Chinese National Standard). A further increase in storage time showed a more obvious increase in the two values. These results are attributed to protein and amino acid decomposition in freshwater shrimp into volatile nitrogen under the action of microorganisms [54]. According to our study, ~0.01 g of intelligent film was suitable for detecting freshness information for 25 g of freshwater shrimp to consumers through a color change in real time. NH3 was selected to simulate the TVB-N that is produced by seafood to evaluate the practical application of the ASKG/ACNF/RCE intelligent films. As shown in Table 3, the L* values decreased as the RCE addition and relative humidity increased, which indicates that the developed film became dark. After increasing the relative humidity to 75%, the a* and the b* values decreased, owing to the acceleration of the contact between RCE and OHions by the hydrophobic ACNF, which accelerated the structural change in RCE.

Detecting Analysis of Intelligent Film for Freshwater Shrimp Freshness in Real Time
When compared with ASKG/CMC·Na/RCE intelligent films in our previous work [25], the color change was slightly different, owing to the scattering and reflection of light that was caused by the long fiber morphology of the ACNF.  Figure 15 shows changes in pH and TVB-N of the freshness shrimp, colorimetric parameters, and a photograph of the intelligent film and they are listed in Table 4. The pH and TVB-N of the fresh freshwater shrimp were 6.831 and 1.4047 mg/100 g, respectively. The intelligent film was dark purple. After 12 h, the two values increased to 7.163 and 20.0759 mg/100 g, respectively. Table 4 shows that the a* value decreased to negative, but the b* value showed opposite changes. The intelligent film was yellow-green. The pH of the freshwater shrimp changed to alkaline and spoilage occurred after 12 h according to GB 2733-2015 (a Chinese National Standard). A further increase in storage time showed a more obvious increase in the two values. These results are attributed to protein and amino acid decomposition in freshwater shrimp into volatile nitrogen under the action of microorganisms [54]. According to our study, ~0.01 g of intelligent film was suitable for detecting freshness information for 25 g of freshwater shrimp to consumers through a color change in real time.

Detecting Analysis of Intelligent Film for Freshwater Shrimp Freshness in Real Time
NH3 was selected to simulate the TVB-N that is produced by seafood to evaluate the practical application of the ASKG/ACNF/RCE intelligent films. As shown in Table 3, the L* values decreased as the RCE addition and relative humidity increased, which indicates that the developed film became dark. After increasing the relative humidity to 75%, the a* and the b* values decreased, owing to the acceleration of the contact between RCE and OHions by the hydrophobic ACNF, which accelerated the structural change in RCE.
When compared with ASKG/CMC·Na/RCE intelligent films in our previous work [25], the color change was slightly different, owing to the scattering and reflection of light that was caused by the long fiber morphology of the ACNF.  Figure 15 shows changes in pH and TVB-N of the freshness shrimp, colorimetric parameters, and a photograph of the intelligent film and they are listed in Table 4. The pH and TVB-N of the fresh freshwater shrimp were 6.831 and 1.4047 mg/100 g, respectively. The intelligent film was dark purple. After 12 h, the two values increased to 7.163 and 20.0759 mg/100 g, respectively. Table 4 shows that the a* value decreased to negative, but the b* value showed opposite changes. The intelligent film was yellow-green. The pH of the freshwater shrimp changed to alkaline and spoilage occurred after 12 h according to GB 2733-2015 (a Chinese National Standard). A further increase in storage time showed a more obvious increase in the two values. These results are attributed to protein and amino acid decomposition in freshwater shrimp into volatile nitrogen under the action of microorganisms [54]. According to our study, ~0.01 g of intelligent film was suitable for detecting freshness information for 25 g of freshwater shrimp to consumers through a color change in real time.

75%
69.48 ± 0.32 a −3.51 ± 0.28 b 28.20 ± 0.64 b 17.09 ± 0.75 b NH3 was selected to simulate the TVB-N that is produced by seafood to evaluate the practical application of the ASKG/ACNF/RCE intelligent films. As shown in Table 3, the L* values decreased as the RCE addition and relative humidity increased, which indicates that the developed film became dark. After increasing the relative humidity to 75%, the a* and the b* values decreased, owing to the acceleration of the contact between RCE and OHions by the hydrophobic ACNF, which accelerated the structural change in RCE.
When compared with ASKG/CMC·Na/RCE intelligent films in our previous work [25], the color change was slightly different, owing to the scattering and reflection of light that was caused by the long fiber morphology of the ACNF.  Figure 15 shows changes in pH and TVB-N of the freshness shrimp, colorimetric parameters, and a photograph of the intelligent film and they are listed in Table 4. The pH and TVB-N of the fresh freshwater shrimp were 6.831 and 1.4047 mg/100 g, respectively. The intelligent film was dark purple. After 12 h, the two values increased to 7.163 and 20.0759 mg/100 g, respectively. Table 4 shows that the a* value decreased to negative, but the b* value showed opposite changes. The intelligent film was yellow-green. The pH of the freshwater shrimp changed to alkaline and spoilage occurred after 12 h according to GB 2733-2015 (a Chinese National Standard). A further increase in storage time showed a more obvious increase in the two values. These results are attributed to protein and amino acid decomposition in freshwater shrimp into volatile nitrogen under the action of microorganisms [54]. According to our study, ~0.01 g of intelligent film was suitable for detecting freshness information for 25 g of freshwater shrimp to consumers through a color change in real time.

Detecting Analysis of Intelligent Film for Freshwater Shrimp Freshness in Real Time
NH3 was selected to simulate the TVB-N that is produced by seafood to evaluate the practical application of the ASKG/ACNF/RCE intelligent films. As shown in Table 3, the L* values decreased as the RCE addition and relative humidity increased, which indicates that the developed film became dark. After increasing the relative humidity to 75%, the a* and the b* values decreased, owing to the acceleration of the contact between RCE and OHions by the hydrophobic ACNF, which accelerated the structural change in RCE.
When compared with ASKG/CMC·Na/RCE intelligent films in our previous work [25], the color change was slightly different, owing to the scattering and reflection of light that was caused by the long fiber morphology of the ACNF.  Figure 15 shows changes in pH and TVB-N of the freshness shrimp, colorimetric parameters, and a photograph of the intelligent film and they are listed in Table 4. The pH and TVB-N of the fresh freshwater shrimp were 6.831 and 1.4047 mg/100 g, respectively. The intelligent film was dark purple. After 12 h, the two values increased to 7.163 and 20.0759 mg/100 g, respectively. Table 4 shows that the a* value decreased to negative, but the b* value showed opposite changes. The intelligent film was yellow-green. The pH of the freshwater shrimp changed to alkaline and spoilage occurred after 12 h according to GB 2733-2015 (a Chinese National Standard). A further increase in storage time showed a more obvious increase in the two values. These results are attributed to protein and amino acid decomposition in freshwater shrimp into volatile nitrogen under the action of microorganisms [54]. According to our study, ~0.01 g of intelligent film was suitable for detecting freshness information for 25 g of freshwater shrimp to consumers through a color change in real time.

90%
68.73 ± 0.47 a −0.70 ± 0.11 c 24.21 ± 0.93 a 12.29 ± 0.51 a 3.12.2. Chroma-Response in NH3 Condition NH3 was selected to simulate the TVB-N that is produced by seafood to evaluate the practical application of the ASKG/ACNF/RCE intelligent films. As shown in Table 3, the L* values decreased as the RCE addition and relative humidity increased, which indicates that the developed film became dark. After increasing the relative humidity to 75%, the a* and the b* values decreased, owing to the acceleration of the contact between RCE and OHions by the hydrophobic ACNF, which accelerated the structural change in RCE.
When compared with ASKG/CMC·Na/RCE intelligent films in our previous work [25], the color change was slightly different, owing to the scattering and reflection of light that was caused by the long fiber morphology of the ACNF.  Figure 15 shows changes in pH and TVB-N of the freshness shrimp, colorimetric parameters, and a photograph of the intelligent film and they are listed in Table 4. The pH and TVB-N of the fresh freshwater shrimp were 6.831 and 1.4047 mg/100 g, respectively. The intelligent film was dark purple. After 12 h, the two values increased to 7.163 and 20.0759 mg/100 g, respectively. Table 4 shows that the a* value decreased to negative, but the b* value showed opposite changes. The intelligent film was yellow-green. The pH of the freshwater shrimp changed to alkaline and spoilage occurred after 12 h according to GB 2733-2015 (a Chinese National Standard). A further increase in storage time showed a more obvious increase in the two values. These results are attributed to protein and amino acid decomposition in freshwater shrimp into volatile nitrogen under the action of microorganisms [54]. According to our study, ~0.01 g of intelligent film was suitable for detecting freshness information for 25 g of freshwater shrimp to consumers through a color change in real time.

Detecting Analysis of Intelligent Film for Freshwater Shrimp Freshness in Real Time
NH3 was selected to simulate the TVB-N that is produced by seafood to evaluate the practical application of the ASKG/ACNF/RCE intelligent films. As shown in Table 3, the L* values decreased as the RCE addition and relative humidity increased, which indicates that the developed film became dark. After increasing the relative humidity to 75%, the a* and the b* values decreased, owing to the acceleration of the contact between RCE and OHions by the hydrophobic ACNF, which accelerated the structural change in RCE.
When compared with ASKG/CMC·Na/RCE intelligent films in our previous work [25], the color change was slightly different, owing to the scattering and reflection of light that was caused by the long fiber morphology of the ACNF.  Figure 15 shows changes in pH and TVB-N of the freshness shrimp, colorimetric parameters, and a photograph of the intelligent film and they are listed in Table 4. The pH and TVB-N of the fresh freshwater shrimp were 6.831 and 1.4047 mg/100 g, respectively. The intelligent film was dark purple. After 12 h, the two values increased to 7.163 and 20.0759 mg/100 g, respectively. Table 4 shows that the a* value decreased to negative, but the b* value showed opposite changes. The intelligent film was yellow-green. The pH of the freshwater shrimp changed to alkaline and spoilage occurred after 12 h according to GB 2733-2015 (a Chinese National Standard). A further increase in storage time showed a more obvious increase in the two values. These results are attributed to protein and amino acid decomposition in freshwater shrimp into volatile nitrogen under the action of microorganisms [54]. According to our study, ~0.01 g of intelligent film was suitable for detecting freshness information for 25 g of freshwater shrimp to consumers through a color change in real time.

Detecting Analysis of Intelligent Film for Freshwater Shrimp Freshness in Real Time
a-c are the significant differences in the same parameters (p < 0.05).
When compared with ASKG/CMC·Na/RCE intelligent films in our previous work [25], the color change was slightly different, owing to the scattering and reflection of light that was caused by the long fiber morphology of the ACNF. Figure 15 shows changes in pH and TVB-N of the freshness shrimp, colorimetric parameters, and a photograph of the intelligent film and they are listed in Table 4. The pH and TVB-N of the fresh freshwater shrimp were 6.831 and 1.4047 mg/100 g, respectively. The intelligent film was dark purple. After 12 h, the two values increased to 7.163 and 20.0759 mg/100 g, respectively. Table 4 shows that the a* value decreased to negative, but the b* value showed opposite changes. The intelligent film was yellow-green. The pH of the freshwater shrimp changed to alkaline and spoilage occurred after 12 h according to GB 2733-2015 (a Chinese National Standard). A further increase in storage time showed a more obvious increase in the two values. These results are attributed to protein and amino acid decomposition in freshwater shrimp into volatile nitrogen under the action of microorganisms [54]. According to our study,~0.01 g of intelligent film was suitable for detecting freshness information for 25 g of freshwater shrimp to consumers through a color change in real time.