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Article

Changes in the Physicochemical Properties of Reduced Salt Pangasius (Pangasianodon hypophthalmus) Gels Induced by High Pressure and Setting Treatment

by
Binh Q. Truong
1,
Binh T. T. Vo
1,
Roman Buckow
2 and
Van Chuyen Hoang
3,*
1
Faculty of Fisheries, Nong Lam University, Ho Chi Minh City 700000, Vietnam
2
School of Agriculture, Biomedicine and Environment, La Trobe Institute for Sustainable Agriculture & Food (LISAF), La Trobe University, Bundoora, Melbourne, Victoria 3086, Australia
3
Faculty of Chemical and Food Technology, HCMC University of Technology and Education, Ho Chi Minh City 700000, Vietnam
*
Author to whom correspondence should be addressed.
Sci 2025, 7(3), 99; https://doi.org/10.3390/sci7030099
Submission received: 11 May 2025 / Revised: 2 July 2025 / Accepted: 11 July 2025 / Published: 17 July 2025
(This article belongs to the Section Biology Research and Life Sciences)
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Abstract

Pangasius (Pangasianodon hypophthalmus) minced muscle with 1 and 2% salt was treated with different high-pressure processing and thermal methods, including conventional heat-induced gels (HIGs), high-pressure processing (HPP) prior to cooking (PC), HPP prior to setting (PS), and setting prior to HPP (SP), to evaluate for their effects on the selected physicochemical properties. The results showed that the PC treatment produced gels with a significantly higher gel strength (496.72–501.26 N·mm), hardness (9.62–10.14 N), and water-holding capacity (87.79–89.74%) compared to the HIG treatment, which showed a gel strength of 391.24 N·mm, a hardness of 7.36 N, and a water-holding capacity of 77.98%. PC gels also exhibited the typical microstructure of pressure-induced gels, with a denser and homogeneous microstructure compared to the rough and loosely connected structure of HIGs. In contrast, SP treatment exhibited the poorest gel quality in all parameters, with gel strength ranging from 319.79 to 338.34 N·mm, hardness from 5.87 to 6.31 N, and WHC from 71.91 to 73.72%. Meanwhile, the PS treatment showed a comparable gel quality to HIGs. SDS-PAGE analysis revealed protein degradation and aggregation in HPP-treated samples, with a decrease in the intensity of myosin heavy chains and actin bands. Fourier-transform infrared spectroscopy (FTIR) analysis showed minor shifts in protein secondary structures, with the PC treatment showing a significant increase in α-helices (28.09 ± 0.51%) and a decrease in random coil content (6.69 ± 0.92%) compared to α-helices (23.61 ± 0.83) and random coil structures (9.47 ± 1.48) in HIGs (p < 0.05). Only the PC treatment resulted in a significant reduction in total plate count (TPC) (1.51–1.58 log CFU/g) compared to 2.33 ± 0.33 log CFU/g in the HIG treatment. These findings suggest that HPP should be applied prior to thermal treatments (cooking or setting) to achieve an improved gel quality in reduced-salt pangasius products.

Graphical Abstract

1. Introduction

In recent years, various processing techniques have been studied to improve the gelation of muscle proteins, including pulsed electric field (PEF) [1], enzymatic cross-linking [2,3,4], ultrasound treatment [5], microwave heating [6], or pH shifting [7]. Among these methods, high-pressure processing (HPP) was studied extensively and attracted attention for its ability to modify protein structures and improve gel formation and texture [8]. Compared to PEF and ultrasound treatment, HPP has been reported to increase gel strength and improve its water-holding capacity by facilitating intermolecular associations among proteins without causing excessive protein denaturation [9]. In low-salt conditions, HPP also showed more consistent and effective improvements in gel strength, water-holding capacity, and protein network integrity compared to alternative non-thermal methods such as ultrasound, enzymatic cross-linking, or microwave treatment [10,11]. These confirm HPP as one of the most promising non-thermal technologies for producing high-quality gels.
In conventional surimi and fish gel processing, sodium chloride is an important factor that contributes to protein solubilization, myofibrillar protein extraction, and the formation of strong gel networks [12,13]. However, high salt concentrations can result in adverse effects on both product stability and consumer health [14]. Recent studies have reported that HPP can induce protein gelation through various molecular interactions, including hydrogen bonding, hydrophobic interactions, and electrostatic forces, even under reduced-salt conditions [15]. Pressure-induced gels typically exhibit smooth, dense, and elastic structures compared to conventional heat-induced gels [16]. Thus, HPP has been applied to enhance the quality of various fish gels at both reduced and conventional salt concentrations, such as those made from Alaska pollock [17], barramundi [18], or Tai Lake whitebait [19].
Setting is another commonly used technique for improving the quality of fish gels. It is an important step in the process of fish protein gelation, particularly in surimi or restructured seafood products [2]. In the setting process, the protein paste is incubated at low to moderate temperatures (typically 25–50 °C) before cooking. This step allows endogenous transglutaminase (TGase) to catalyze cross-linking reactions between myofibrillar proteins, primarily through ε-(γ-glutamyl) lysine bonds [3,4]. This enzymatic reaction helps to improve the formation of the protein network, leading to a better gel texture and water-holding capacity [20,21]. Gels produced with a setting step have been reported to exhibit superior textural and water-holding properties, as well as improved sensory quality, compared to conventional heat-induced gels under similar conditions [22,23,24]. Therefore, setting is especially beneficial to reduce salt levels in muscle gelation as it increases protein aggregation and gel stability at low salt concentrations [4,25].
Although both HPP and setting have been reported to enhance the quality of fish gels in conventional and reduced-salt conditions, their combined application can lead to variable results depending on several factors, such as the type of fish protein, treatment order, and processing conditions. Moreover, there is currently limited understanding of the mechanisms by which HPP and setting interact in fish muscle systems, particularly under low-sodium conditions.
Pangasius catfish is widely cultured and processed in Southeast Asia as an economically important freshwater fish species [26]. Pangasius fish are appreciated for their nutritional content and low market price and have a taste comparable to other popular whitefish species [27,28]. In their value-added form, pangasius catfish is widely used in various products, including fillets, surimi, and restructured fish gels in many countries with high market demand [29]. However, to date, no research has been conducted to investigate the application of advanced technologies such as HPP to pangasius gels, and the use of commonly applied methods for improving gel quality, such as setting—particularly under reduced-salt conditions—also remains unstudied.
Therefore, this study aims to evaluate the effects of high-pressure processing (HPP) and setting treatments on the gelation properties of pangasius muscle at both reduced (1%) and conventional (2%) salt concentrations in order to gain a better understanding of the mechanisms involved in their combined application and to identify suitable processing conditions for producing high-quality pangasius gels under reduced-salt conditions.

2. Materials and Methods

2.1. Materials and Fish Gel Preparation

Pangasius fish (weighing approximately 4–5 kg/each) were purchased from a local aquaculture farm in Chiang Mai, Thailand. The fish were immediately transported to the laboratory on ice within 2 h, filleted manually, and the muscle tissues were trimmed of skin and bones. The fish muscle (0.8–1 kg/each) was then cut into small cubes and frozen in an air-blast freezer for 4 h. The frozen fillets were then minced with 1% or 2% (w/w) sodium chloride (NaCl) for about 3 min. The temperature of the fish paste was maintained below 4 °C during the mincing step. The final moisture content of the minced fish muscle was adjusted to 80%, and it was stuffed into collagen casings (24 mm in diameter × 100 mm in length). A total of six sausage samples were prepared per treatment group. Our preliminary experiment has shown that pangasius gels without added salt are weak, fragile, and unstable.

2.2. High-Pressure and Thermal Treatment of Pangasius Paste

HPP treatment was performed using high-pressure equipment (Baotou Kefa High Pressure Technology Co., Ltd., Baotou, China) equipped with a 5 L chamber and a maximum pressure level of 600 MPa. The minced pangasius muscle was pressurized at 500 MPa for 10 min, with an initial temperature below 10 °C. Setting processing was performed in a water bath at 40 °C for 2 h, and the samples were then rapidly cooled in ice for 15 min. The cooking step involved the immersion of fish gels in water at 90°C for 30 min, which were subsequently cooled in ice for 15 min. The experimental design is shown in Table 1. For comparison, conventional heat-induced gels (HIGs) were prepared by cooking (90 °C for 30 min) minced pangasius muscle with added salt (2%), then cooling this under identical conditions in ice for 15 min.

2.3. Proximate Analysis

The proximate composition of raw minced pangasius muscle was analyzed before the addition of salt, including moisture, ash, protein, and fat content. Standard AOAC methods were used to determine the proximate composition [30]. Moisture content was measured by drying the sample at 105 °C to a constant weight (AOAC 950.46). Crude proteins were analyzed using the Kjeldahl method (AOAC 981.10), in which the nitrogen content was measured and multiplied by a conversion factor of 6.25 to obtain the protein content. The lipid content was measured by Soxhlet extraction using petroleum ether as the solvent (AOAC 991.36), and ash content was determined by incinerating the samples in a furnace at 550 °C for 6 h (AOAC 920.153). All analyses were performed in triplicate.

2.4. Total Plate Count (TPC)

For TPC analysis, about 10 g of the pangasius gel was homogenized in 90 mL of sterile diluent using a homogenizer (HG-15A, Daihan, Wonju, Korea) for 60 s. Serial decimal dilutions were prepared by adding 1 mL of the homogenized solution into 9 mL of sterile diluent solution, and a series of decimal dilutions were made up to 10−5. About 0.1 mL of the serial dilution was spread onto sterilized Petri dishes for microbial enumeration. The TPC was determined after incubation at 37 °C for 48 h [31].

2.5. Color Analysis

The color of pangasius gels was measured using a Konica Minolta chromometer (CR-400, Tokyo, Japan). Color values, including L* (lightness), a* (red-green), and b* (yellow-blue), were used to calculate whiteness and the total color difference (∆E) using the following formulas [32,33]:
W h i t e n e s s = 100 − [ 100 − L 2 + a 2 + b 2 ] 1 / 2
∆ E = [ △ L 2 + △ a 2 + △ b 2 ]
where △L, △a, and △b indicate the differences in color measurements between HPP and HIG samples.

2.6. Mechanical Properties

Pangasius gel samples with a size of 2.4 cm × 3 cm were removed from casings and tempered at 25 °C for 2 h prior to gel strength analysis. A texture analyzer (TA-XT plus, Stable Micro Systems Ltd., Godalming, UK) with a cylindrical plunger (40 mm in diameter) and a 200 N load cell was used to investigate the gel strength at a speed of 2 mm/min. Gel strength was obtained as breaking force × breaking deformation [34]. Similarly, the hardness and springiness of pangasius gel samples (2.4 cm × 3 cm) were evaluated using the same texture analyzer with a cylindrical plunger (40 mm in diameter) and a load cell (200 N) at a compression rate of 2 mm/min, compressing samples to 50% of the fish gels’ height.

2.7. Protein Solubility

Protein solubility was measured following the method of Truong, Buckow, and Nguyen [35] with minor modifications. Pangasius gel samples (4 g) were homogenized with 40 mL of a 30 g/L NaCl solution for 1 min, followed by centrifugation at 1500× g for 15 min at 5 °C. A 1 mL aliquot of the supernatant was added to 10 mL of the 30 g/L NaCl solution, and the protein content was assessed spectrophotometrically at 550 nm using the Lowry method, using bovine serum albumin as the standard for quantifying proteins.

2.8. Water-Holding Capacity (WHC)

Pangasius gels (about 2 g) were wrapped with filter papers and then centrifuged at 9000× g and 20 °C for 20 min (Universal 320R centrifuge, Hettich, Germany). The WHC was calculated as the percentage of water retained relative to the initial water content [36].

2.9. SDS-Polyacrylamide Gel Electrophoresis (SDS-PAGE)

Protein extraction:
Total SDS-soluble and sarcoplasmic protein fractions were extracted following the method of Pazos et al. [37]. To extract total SDS-soluble proteins, 0.5 g of pangasius gels was thoroughly mixed with eight volumes of Tris buffer (10 mM Tris-HCl, pH 7.2), supplemented with 2% SDS as a denaturant and 5 mM phenylmethylsulfonyl fluoride (PMSF) as a protease inhibitor, and homogenized thoroughly. After boiling, the homogenate was processed with an Ultra-Turrax device and then centrifuged at 40,000× g for 12 min at 4 °C. The collected supernatant was designated as the total SDS-soluble protein fraction. For the extraction of sarcoplasmic proteins, 0.5 g of fish gel was homogenized in eight volumes of non-denaturing Tris buffer (10 mM Tris-HCl, pH 7.2) with 5 mM PMSF for 2 min. The homogenate was centrifuged (40,000× g/12 min) at 4 °C, and the resulting supernatant was labeled as the sarcoplasmic protein fraction. Total SDS-soluble and sarcoplasmic protein fractions were kept at −80 °C until electrophoretic analysis. For comparison, two protein fractions of raw minced pangasius muscle were also analyzed using SDS-PAGE.
SDS–PAGE analysis:
To conduct SDS-PAGE, 1D 10% (v/v) polyacrylamide gels were prepared in the laboratory using an acrylamide to N,N’-ethylene bis-acrylamide ratio of 200:1. The stacking gel (4% polyacrylamide) was loaded with 30 µg of protein per well, and electrophoresed at 60 V for 30 min. The proteins were subsequently separated at 100 V for 90 min using the Mini-PROTEAN 3 cell system (Bio-Rad, Hercules, CA, USA). The running buffer was prepared with 1.44% (w/v) glycine, 0.67% Tris-base, and 0.1% SDS. Overnight staining of the gels was performed using the Coomassie PhastGel Blue R-350 dye (GE Healthcare, Chicago, IL, USA).

2.10. Fourier-Transform Infrared Spectroscopy (FTIR)

An FT-IR 4700 spectrometer (JASCO, Tokyo, Japan) with an ATR prism crystal attachment was used to conduct the FTIR analysis. Pangasius gels (approximately 1 mg) were placed on the ATR crystal surface at room temperature and pressure was applied with a flat-tip plunger to obtain clear spectral peaks. Infrared spectra were measured within the range of 4000 to 650 cm−1 and all measurements were performed in triplicate. The spectral resolution was maintained at 4 cm−1. To improve the spectral resolution, background subtraction and a second derivative analysis were applied using OriginPro 2024 software.

2.11. Scanning Electron Microscopy (SEM)

The microstructures of pangasius gels were observed following the method of Iwasaki et al. (2005) [38] with minor modifications. The center of gel samples was cut into square blocks (1 mm in thickness × 2 cm2 in area) then fixed in 2.5% glutaraldehyde and dehydrated by ethanol with increased concentrations (50%, 70%, 90%, and 100%). After dehydration, the samples were treated with 2-methyl-2-propanol to replace the ethanol and then subjected to freeze-drying. Samples were sputter-coated in a vacuum with platinum–palladium. The microstructures of pangasius gels were observed using a Hitachi TM4000 plus SEM (Tokyo, Japan) at 10 kV.

2.12. Statistical Analysis

All analytical measurements were performed in four replications, and the results are reported as mean values ± standard deviation. Tukey’s test was used for post hoc comparisons following a one-way ANOVA to assess differences among treatments. Statistical significance was set at p < 0.05 (SPSS version 21.0, IBM Corp., Armonk, NY, USA).

3. Results and Discussion

3.1. Proximate Analysis

The protein, fat, ash, and moisture content of pangasius minced muscle was analyzed in triplicate. The proximate composition analysis of pangasius minced muscle showed high protein (16.24 ± 0.17%) and moisture contents (80.02 ± 0.3%), with relatively low levels of fat (1.12 ± 0.03%) and ash (1.77 ± 0.4%). Particularly, the crude protein of pangasius minced muscle in this study is higher than that of the frozen pangasius fillet in the study by Guimarães et al. [39]. However, similar crude lipid and ash contents were also observed between the two proximate analyses.

3.2. TPC

The results in Table 2 showed that the TPC of PC1 and PC2 samples was markedly reduced compared to the other treatments (p < 0.05). A possible explanation could be that the combined effects of HPP and cooking could help to better deactivate some spore-forming bacteria that are resistant to heat treatment only. A similar observation was reported by Yu et al. [40], where cooked rice spoiled after 3 days of storage as a result of spore-forming microorganisms, including Bacillus cereus and Bacillus subtilis. However, the application of HPP (400–600 MPa/10 min) followed by cooking (100 °C/10 min) was able to inactivate bacteria for at least 56 days. In contrast, the combination of setting and HPP did not improve the TPC of pangasius gels compared to HIGs (p < 0.05). This result indicates that setting at 40 °C prior to HPP did not result in a similar effect compared to processing methods that allow spore germination before HPP. The TPC results demonstrate that HPP at 500 MPa before cooking (90 °C/30 min) effectively reduces microbial numbers in pangasius gels, suggesting that this treatment may contribute to extending the shelf life of pangasius gels. However, further studies on microbial quality over storage are required to confirm this effect in pangasius gel products.

3.3. Color Analysis

The results on the whiteness and ∆E of pangasius gels induced with different gelling methods are shown in Table 3. PC1 and PC2 (pressurization then cooking) samples exhibited significantly higher whiteness as compared to other treatments (p < 0.05), whereas SP1 and SP2 samples had the lowest whiteness values among the treatments (p < 0.05). The whiteness values of HIG, PS1, and PS2 samples were similar and higher than those of SP1 and SP2 but lower than PC1 and PC2. The combination of HPP and heat treatment likely caused greater protein denaturation than heat treatment alone, which contributed to the increased whiteness of PC gels compared to HIGs. In addition, HPP may also disrupt the heme group and unfold globin proteins, thereby contributing to the higher whiteness of PC gels [41]. Changes in the whiteness of fish gels are associated with protein aggregation and cross-linking, forming compact networks that reflect more light [42]. Possibly, the lower whiteness of the SP treatment indicates that less protein denaturation was induced than that for PC, PS, and HIG treatment. Similar observations were noted regarding the whiteness of barramundi gels induced by setting prior to HPP in the study of Truong et al. [43]. Salt concentration did not significantly affect the whiteness of pangasius gels.
The visual difference in color among fish gel samples is represented by ΔE, with greater color differences indicated by higher ΔE values [33]. ΔE values < 3 indicate similar colors, ΔE values of 3 to 6 indicate very distinctive differences, and ΔE values of 6.0 to 12 indicate strong differences [44]. The results of ΔE values shown in Table 1 show that only the PC treatment resulted in strong differences in color as compared to HIGs (Figure 1).

3.4. Mechanical Properties

The mechanical properties of pangasius gels treated with different high-pressure and setting conditions are presented in Table 4. The gel strength of pangasius gels ranged from 319.79 N.mm to 501.26 N.mm, with the PC treatment exhibiting a significantly higher gel strength compared to HIG, PS, and SP treatments regardless of salt concentration (p < 0.05). PS gels showed a similar gel strength to HIGs at both salt concentrations, while the gel strength of SP gels at both salt concentrations was significantly lower than that of HIG, PC, and PS gels (p < 0.05). As the SP treatment was incubated at 40 °C, causing the partial protein denaturation of pangasius proteins, this prevented the impact of high pressure on the ability of muscle proteins to form gels, as mentioned by several previous studies [45,46]. This resulted in weaker mechanical properties of pangasius gels, which was induced by setting prior to HPP due to incomplete gel formation. It is hypothesized that incubating fish gels at 40–50 °C can enhance the activity of TGase, an enzyme that catalyzes acyl transfer reactions between acyl donors and acceptors [47,48]. This leads to the formation of ε-(γ-glutamyl) lysine cross-links, thereby improving the gel strength. In this study, TGase activity did not produce a sufficient effect to improve the incomplete structure formation of SP pangasius gels. Therefore, a longer setting time or a final cooking step is necessary to support gel formation in the SP treatment. Similarly, Kunnath, Bindu, et al. [49] reported a significantly lower gel strength in pink perch gels subjected to setting (25 °C for 30 min) prior to HPP (250 MPa/30 °C/12 min) compared to HIGs (90 °C/40 min). However, the PS samples of pink perch gels also exhibited significantly lower gel strengths than HIG, which contrasts with the findings of this study.
In the study of Hwang, Lai, and Hsu [45], setting (50 °C/60 min) prior to HPP (200 MPa, 4 °C, 60 min) resulted in a higher gel strength in tilapia gels compared to HIGs (90 °C/20 min), while HPP prior to setting produced the highest gel strength among all treatments. However, Truong et al. [43] reported similar results to those of this study, in which setting prior to HPP could prevent gel-forming and reduce the gel strength of barramundi gels. On the other hand, in Truong et al.’s study [43], PS treatment resulted in a higher gel strength than PC treatment at a 2% salt concentration, and this study showed that PC treatments of pangasius gels produced higher gel strengths than PS treatment at both 1% and 2% salt concentrations. This could be explained by the intrinsic differences in the composition between barramundi and pangasius muscle. For example, myofibrillar protein content, connective tissue structure, endogenous enzyme activity, etc., may influence the gelation behavior of fish protein under different gelling conditions [16,43]. In summary, PC and PS treatments induced pangasius gels with higher or comparable gel strengths compared to HIGs at both salt concentrations.
The hardness of PC2 was 10.14 ± 1.27 N, the highest among the treatments, while the lowest hardness was observed in the SP1 treatment (5.87 ± 0.67 N). Similar to the gel strength, the hardness of PC and PS treatments was higher or comparable to that of HIGs. In addition, HIG, PC, and PS treatments also induced pangasius gels with significantly higher hardnesses than the SP samples (p < 0.05). Similarly, the study of Truong et al. [43] reported higher hardnesses in PC and PS barramundi gels as compared to SP gels. In contrast, the study of Angsupanich and Ledward [50] found that the hardness of gels that underwent HPP (400 MPa/20 min/RT) prior to cooking (50 °C/10 min) and gels that underwent cooking prior to HPP had similar hardnesses as compared to heat treatment (50 °C/10 min).
The springiness of pangasius gels ranged from 0.86 mm to 0.96 mm. PS1 and PS2 gels showed the highest elasticity values at 0.91 mm and 0.96 mm, respectively, which were significantly higher than HIGs and other treatments (p < 0.05). However, no significant differences in springiness were observed between the different salt concentrations. The increase in the springiness of PS gels, as compared to PC gels, SP gels, and HIGs, could be explained by the activity of TGase during the setting step, leading to an increase in the formation of ε-(γ-glutamyl) lysine bonds and contributing to a more elastic gel network. Similarly, catfish (Clarias gariepinus) gels treated with setting (35 °C/60 min) prior to cooking (90 °C/20 min) also exhibited greater springiness as compared to cooking (90 °C/20 min) [51].

3.5. Protein Solubility

The protein solubility of HIG and HPP samples ranged from 8.20 ± 0.39 mg to 18.57 ± 0.79 mg, as presented in Figure 2A. The SP treatment exhibited significantly higher protein solubility compared to the other groups (p < 0.05). Protein solubility, an important indicator of muscle protein functionality, reflects the degree of denaturation and aggregation caused by processing treatments such as heat or HPP, particularly in myofibrillar proteins that form the gel network. A higher protein solubility indicates that the proteins are not fully denatured and thus have a reduced ability to form a strong gel structure. In contrast, a reduction in solubility indicates the formation of insoluble protein aggregates or networks, which can enhance gelation. The significantly higher protein solubility of SP gels can be attributed to the partial denaturation of pangasius proteins during the setting step at 40 °C prior to HPP treatment. This could prevent the proteins from fully denaturing, thereby inhibiting the formation of a stable gel network under high pressure. A similar observation on barramundi gels subjected to setting prior to cooking was also reported by Truong et al. [43]. Salt concentrations showed no significant effect on protein solubility, indicating that the effect of processing methods was dominant in the changes in protein solubility.

3.6. Water-Holding Capacity

Figure 2B shows the WHC of pangasius gels induced with different gelling methods ranging from 71.91% to 89.74%. At both 1 and 2% salt concentrations, PC gels exhibited a significantly higher WHC as compared to all other treatments (p < 0.05), while the SP treatment showed the lowest WHC, which corresponded to its higher protein solubility. The PS treatment also produced gels with a WHC similar to HIGs but significantly lower than the PC treatment (p < 0.05). This suggested that the PC treatment effectively promoted protein denaturation and gel formation in a way that improved the water-binding capacity of the gel matrix as compared to other treatments. The combined effect of HPP followed by cooking may promote protein unfolding and the formation of intermolecular interactions, such as hydrophobic and hydrogen bonds. These interactions could contribute to a stronger gel matrix and enhance its ability to retain water [52]. In addition, the myofibrillar structure may be disrupted and degraded into smaller protein fragments, which increase protein solubility and promote binding between free water and fish proteins [53]. Cando et al. [12] also suggested that the increase in the WHC of Alaska pollock surimi pressurized prior to cooking could be induced by the exposure of the hydrophobic groups of the fish protein, enhancing hydrophobic interactions and stabilizing the water/protein system. The increase in the WHC of fish gels that were pressurized and then cooked was also observed in barramundi gels [18] and Nemipterus virgatus [52].
In contrast to PC gels, the SP treatment exhibited the lowest WHC among all treatments (p < 0.05). This result also corresponded with the findings on mechanical properties and protein solubility, confirming that a weak gel network was formed with the SP treatment, as explained in the sections above. However, the SP treatment (25 °C for 30 min followed by 250 MPa at 30 °C for 12 min) and PS treatment (250 MPa at 30 °C for 12 min followed by 25 °C for 30 min) on pink perch gels significantly reduced expressible water compared to the cooked treatment (p < 0.05), although both treatments exhibited markedly lower gel strengths (p < 0.05) [49]. Similar to the PC treatment, the PS treatment also resulted in the initial formation of a gel network induced by HPP, followed by a final formation of fish gels by heating. However, the subsequent heating (40 °C/2 h) of setting provided a lesser thermal effect to fully stabilize the protein network of pangasius gels than cooking (90 °C/30 min), leading to a gel structure with a weaker WHC compared to PC. The salt concentration did not result in any significant effect on the WHC of pangasius gels.

3.7. SDS-Polyacrylamide Gel Electrophoresis (SDS-PAGE)

Figure 3S shows the electrophoresis profile of SDS-soluble proteins in pangasius gels, with the myosin heavy chain (MHC) appearing at approximately 250 kDa and the actin band at around 45 kDa [42]. The MHC band of the raw minced muscle sample (lane RMS) was prominent and intense, indicating the native, soluble form of raw proteins. With the heat, HPP, and setting treatments, the intensity of this band was significantly reduced in all treated samples, suggesting protein denaturation and aggregation. In addition, protein bands of SDS with lower molecular weights (<35 kDa) were observed in the heat, HPP, and setting samples compared to the raw mince samples, indicating myofibrillar degradation or fragmentation during the treatment [8]. Compared to HIGs, the SDS-PAGE profile of samples treated with HPP prior to cooking exhibited protein bands with higher intensity and greater diversity, suggesting that HPP followed by cooking induced more controlled and less destructive aggregation compared to the rapid and extensive aggregation of heat alone. The band intensity of PS2 (lane 5S) was lower than HIGs and other treatments, suggesting that PS2 treatment can promote more protein aggregation, possibly due to the formation of more intermolecular bonds and protein–protein interactions, contributing to a stronger gel network [54]. This also corresponds to the lower protein solubility, higher mechanical properties, and higher WHC of the PS2 gel when compared to other treatments. The reduction in the MHC band’s intensity was also observed in the myofibrillar proteins of cod (Gadus morhua) [50] or arrowtooth flounder (Atheresthes stomias) [42]. In contrast, the actin band (45 kDa) was generally similar among the treatments, indicating that actin was less affected by the treatments and may play a less significant role in pangasius gel formation.
For sarcoplasmic proteins, HPP treatment at 500 MPa reduced the intensity of high-molecular-weight bands, such as myosin heavy chains (MHCs), and increased the intensity of lower-molecular-weight bands. These changes were consistently observed regardless of whether the HPP was combined with setting or cooking treatments, suggesting that pressure was the primary factor responsible for protein fragmentation (Figure 3R). This suggests that high-pressure processing may have induced partial protein degradation or aggregation, leading to the fragmentation or reduced extractability of large protein molecules in the sarcoplasmic fraction [37]. The actin band (45 kDa) also disappeared and was shifted to a lower band in all treatments, indicating that the samples were denatured and underwent degradation or aggregation under both high-pressure and thermal conditions.

3.8. Fourier-Transform Infrared Spectroscopy (FTIR)

FTIR was used to gain insights into the secondary structure of pangasius gels treated with different HPP and thermal treatments. The analysis showed that the overall FTIR spectra of the different treatments did not exhibit major changes, with relatively consistent peak positions and absorbance intensities (Supplementary Figure S1).
In particular, characteristic bands, including amide A, were observed at around 3300 ± 20.24 cm−1. Amide I was observed at 1624.55 ± 2.68 cm−1, and amide II at 1544.52 ± 1.16 cm−1 [55]. The amide A bands correspond to O-H and N-H stretching vibrations, where the broad absorbance reflects the muscle’s high water content [56]. The amide I band, primarily derived from C=O stretching vibrations, reflects contributions from secondary structures such as α-helices, β-sheets, turns, and unordered regions. These are influenced by hydrogen bonding, dipole interactions, and the backbone conformation of the peptide [11]. In contrast, amide 2 (1480–1575 cm−1) was produced from in-plane N–H bending vibrations, which contribute approximately 40–60% of the band’s potential energy, along with C–N stretching, accounting for about 18–40% [55]. Among these bands, the amide I band (ranging from 1700 to 1600 cm−1) is considered the most informative and important band for assessing the protein’s secondary structure due to its sensitivity to the arrangement of the polypeptide backbone [12]. In general, the intensity of the amide 1 band of all treatments is lower than HIGs, except for SP1, which was similar to HIGs, suggesting that different mechanisms may be involved in the secondary structure changes of myofibrillar proteins between heat and pressure treatments. However, only minor changes in the protein structure were observed as the amide I band frequencies showed little variation in all treatments.
The structural changes of myofibrillar proteins were investigated by analyzing the amide I region (1700–1600 cm−1) through second derivative and deconvolution spectra (Supplementary Figure S2) to quantify the proportions of α-helices, β-sheets, and other secondary structures present in the gels. Approximately 10 distinct bands were identified at 1603.80 ± 0.47, 1625.42 ± 0.47, 1632.72 ± 0.73, 1637.51 ± 0.48, 1646.57 ± 0.76, 1654.49 ± 0.36, 1665.23 ± 0.05, 1674.87 ± 0.03, 1682.31 ± 1.07, and 1695 ± 0.39 cm−1. The bands at 1625.42 ± 0.47, 1632.72 ± 0.73, 1637.51 ± 0.48, and 1695 ± 0.39 cm−1 correspond to β-sheet structures, while the bands at 1674.87 ± 0.03 and 1682.31 ± 1.07 cm−1 are attributed to β-turns [56]. Meanwhile, the bands at 1654.49 ± 0.36 and 1665.23 ± 0.05 cm−1 are assigned to α-helices, and the band at 1646.57 ± 0.76 cm−1 is attributed to a random coil structure. In addition, the band at 1603.80 ± 0.47 cm−1 could be attributed to the aromatic side chain vibrations of amino acids such as tyrosine, phenylalanine, or tryptophan [57,58,59].
The impact of high-pressure and thermal treatments on the secondary structure of pangasius proteins, revealed through FTIR deconvolution, is shown in Table 5. Compared to HIG, the α-helix content of PC1 (28.04 ± 0.91) and PC2 (28.09 ± 0.51) was significantly higher (p < 0.05). In contrast, a significant reduction in random coil content was also observed in PC treatment compared to HIGs (p < 0.05). The content of β-sheets, β-turns, random coil structures, and aromatic side chains in the PC treatment was similar to those of HIGs. These results suggested that the effect of HPP prior to cooking may help to stabilize α-helical structures. The preservation of α-helices under HPP is likely associated with the ability of HPP to maintain intramolecular hydrogen bonds, preventing structural disruption during the cooking step. This finding is consistent with the study of Chen et al. [60], in which pressurization prior to cooking in flying fish surimi exhibited a higher α-helix content compared to samples treated with heat alone. The previous reports also suggested that β-sheets and β-turns are resistant to both thermal and pressure-induced conformational changes due to strong inter-chain hydrogen bonds [61,62]. In agreement, a similar content of β-sheets and β-turns, as compared to that of HIGs, was observed in this study. The reduction in the random coil structures of the PC treatment as compared to HIGs was also consistent with observations in flying fish surimi [63], hake myofibrils [12], or Nemipterus virgatus gels [64].
PS and SP treatments showed similar α-helix, β-sheet, β-turn, and aromatic side chain contents to all other treatments (p > 0.05), regardless of salt concentration. Notably, PS and SP treatments showed similar α-helix contents as compared to PC and HIGs, even though the PC treatment showed a protective effect on α-helices as compared to HIGs. Although setting is a milder thermal treatment, the α-helix content did not increase as observed for the PC treatment. This result can be explained by the reduction in α-helix content during the setting step, as reported by Ogawa et al. [65], who found a significant decrease in the α-helical content of fish actomyosin during setting at 30–40 °C. Therefore, when HPP is combined with setting, the structural protection may be counteracted by the unfolding induced by setting, resulting in intermediate α-helix levels, as observed in the PS and SP treatments compared to HIG and PC treatments. Similar to the PC treatment or HIGs, the β-sheet and β-turn contents of PS and SP treatments remained unaffected, reflecting their stability under thermal and high-pressure treatments. Similarly, HPP (500 MPa/10 min) prior to two-step thermal gelation (40 °C/30 min followed by 90 °C/20 min) also produced the same β-sheet and β-turn contents when compared to heating alone (40 °C/30 min followed by 90 °C/20 min) [65]. In contrast to β-sheet and β-turn contents, the amount of random coil structures was significantly reduced under PS and SP treatments as compared to HIGs. This suggests that HPP may have a more pronounced effect on random coil structures, regardless of the applied thermal treatments.

3.9. Scanning Electron Microscopy (SEM)

The physical properties of gels are largely influenced by their microstructure, and the analysis of gel microstructures provides valuable insight into the mechanisms of gel formation [66]. The scanning electron microscopy (SEM) images showed the differences in the microstructure of pangasius gels under various HPP and thermal treatments, which corresponded with their mechanical properties and WHC (Figure 4).
Compared to PC and PS treatments, HIGs exhibited a porous and loosely connected network, which is typically associated with weaker gelation and lower gel strength. In contrast, the PC treatment led to a denser and more homogeneous structure than HIGs, corresponding to higher mechanical properties and WHC. Similar observations have been reported in other studies on HPP-assisted gelation, such as in Alaska pollock surimi [12], barramundi gels [35], or sardine gels [34]. PS1 and PS2, subjected to pressure followed by setting, showed relatively improved microstructures compared to HIGs, though they were still more porous than PC samples. Conversely, SP1 and SP2, treated by setting prior to pressurization, showed irregular structures with larger voids, resulting in the lowest gel strength and WHC. The weak network of SP could be attributed to protein denaturation occurring during the setting step, which limits the effectiveness of subsequent pressurization in enhancing gelation [35]. These findings indicate that the application of HPP before thermal treatment is more effective than applying thermal treatment first for enhancing gelation in pangasius minced muscle.
Overall, the SEM observations confirmed the mechanical and WHC results, suggesting that HPP prior to thermal treatment facilitates the formation of stronger and more stable gel matrices. These findings also support the potential of HPP in improving the textural and functional properties of gel products, even under reduced-salt conditions.

4. Conclusions

The combination of different gelling methods (heat, setting, and pressure) resulted in different gelation patterns, leading to varied physicochemical properties in pangasius gels. The pressure followed by cooking (PC) treatment showed the highest mechanical properties and WHC, with a denser and more uniform microstructure as observed by SEM. The pressure prior to setting (PS) treatment exhibited lower mechanical properties and WHC compared to PC. However, its mechanical properties and WHC were comparable to those of HIGs, despite a milder thermal treatment (setting) rather than full cooking, as performed for HIGs. This finding suggests that the application of HPP at 500 MPa could facilitate pangasius protein gelation under reduced-heat conditions, demonstrating its potential for developing a reduced-sodium gel from pangasius muscle with mild thermal treatment. In contrast, the setting prior to HPP (SP) treatment showed the poorest gel properties for all parameters due to partial protein denaturation during the setting stage, which can inhibit the effects of pressure treatment on gelation. The PC treatment showed a significant reduction compared to HIGs, suggesting the potential of PC treatment to not only enhance gel quality but also to improve the microbiological quality of pangasius gels. The SDS-PAGE analysis showed a reduction in the intensity of MHC and actin and increased low-molecular-weight fragments under HPP treatment, indicating protein degradation and aggregation. The combination of HPP and thermal treatment could induce changes in the secondary structures of pangasius gels in different ways. For example, the PC treatment increased the α-helix content and reduced random coil structures, while the SP and PS treatments decreased the random coil content without affecting the α-helix content.
Further research is needed to gain insight into the mechanisms of bond formation. In addition, a longer setting time or combining cross-linking enzymes could be employed to improve gel quality. Moreover, sensory quality, nutritional value, and shelf-life stability studies should be done to ensure practical applicability and consumer acceptance.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/sci7030099/s1, Supplementary Figure S1. FTIR spectra of pangasius gels under different HPP and thermal treatments over the frequency range 4000–500 cm−1. Supplementary Figure S2. Second derivative of the amide I band (1700–1600 cm−1) of the infrared spectra of pangasius gels with 1 and 2% salt under different HPP and thermal treatments.

Author Contributions

Conceptualization, B.Q.T. and R.B.; methodology, B.Q.T. and R.B.; software, B.Q.T., B.T.T.V. and V.C.H.; validation, B.Q.T. and V.C.H.; formal analysis, B.Q.T., V.C.H. and B.T.T.V.; investigation, B.Q.T., V.C.H. and B.T.T.V.; resources, B.Q.T. and R.B.; data curation, B.Q.T. and V.C.H.; writing—original draft preparation, B.Q.T. and V.C.H.; writing—review and editing, V.C.H., R.B. and B.Q.T.; visualization, B.Q.T. and V.C.H.; supervision, V.C.H.; project administration, B.Q.T.; funding acquisition, B.Q.T. and R.B. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the Vietnam Ministry of Education and Training under the project titled ‘Research on high-pressure processing technology applied to pangasius (Pangasianodon hypophthalmus) muscle and its application in developing value-added products’, grant No. B2023-NLS-02.

Informed Consent Statement

Not applicable.

Data Availability Statement

The original contributions presented in this study are included in the article; further inquiries can be directed to the corresponding author.

Conflicts of Interest

The authors declare no conflicts of interest.

Abbreviations

The following abbreviations are used in this manuscript:
HPPHigh-pressure processing
WHCWater-holding capacity
MHCMyosin heavy chain
FTIRFourier-transform infrared spectroscopy
TGaseEndogenous transglutaminase
TPCTotal Plate Count
SEMScanning Electron Microscopy
PMSFphenylmethylsulfonyl fluoride
LSDleast significant difference

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Figure 1. Visual appearance of the color of pangasius fish gels treated under different thermal and pressure conditions. HIGs: conventional heat-induced gels; PS1: 1% salt concentration, 500 MPa/10 °C/10 min, and 40 °C/2 h; PS2: 2% salt concentration, 500 MPa/10 °C/10 min, and 40 °C/2 h; PC1: 1% salt concentration, 500 MPa/10 °C/10 min, and 90 °C/30 min; PC2: 2% salt concentration, 500 MPa/10 °C/10 min, and 90 °C/30 min; SP1: 1% salt concentration, 40 °C/2 h min, and 500 MPa/10 °C/10 min; SP2: 2% salt concentration, 40 °C/2 h, and 500 MPa/10 °C/10 min.
Figure 1. Visual appearance of the color of pangasius fish gels treated under different thermal and pressure conditions. HIGs: conventional heat-induced gels; PS1: 1% salt concentration, 500 MPa/10 °C/10 min, and 40 °C/2 h; PS2: 2% salt concentration, 500 MPa/10 °C/10 min, and 40 °C/2 h; PC1: 1% salt concentration, 500 MPa/10 °C/10 min, and 90 °C/30 min; PC2: 2% salt concentration, 500 MPa/10 °C/10 min, and 90 °C/30 min; SP1: 1% salt concentration, 40 °C/2 h min, and 500 MPa/10 °C/10 min; SP2: 2% salt concentration, 40 °C/2 h, and 500 MPa/10 °C/10 min.
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Figure 2. Protein solubility (A) and water-holding capacity (B) of pangasius gels with 1 and 2% salt added under different HPP and thermal conditions. Values with different letters (a, b, c) are significantly different (p < 0.05).
Figure 2. Protein solubility (A) and water-holding capacity (B) of pangasius gels with 1 and 2% salt added under different HPP and thermal conditions. Values with different letters (a, b, c) are significantly different (p < 0.05).
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Figure 3. SDS-PAGE profiles of SDS-soluble (S) and sarcoplasmic (R) proteins from pangasius gels treated under different pressure and thermal conditions. M: molecular ladder; RMS: SDS-soluble protein of raw minced muscle; 1S/1R: HIG; 2S/2R: SP1; 3S/3R: SP2; 4S/4R: PC1; 5S/5R: PC2; 6S/6R: PS1; 7S/7R:PS2.
Figure 3. SDS-PAGE profiles of SDS-soluble (S) and sarcoplasmic (R) proteins from pangasius gels treated under different pressure and thermal conditions. M: molecular ladder; RMS: SDS-soluble protein of raw minced muscle; 1S/1R: HIG; 2S/2R: SP1; 3S/3R: SP2; 4S/4R: PC1; 5S/5R: PC2; 6S/6R: PS1; 7S/7R:PS2.
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Figure 4. SEM images of pangasius gels containing 1% and 2% salt under different high-pressure and thermal conditions. HIGs: conventional heat-induced gels; PS1: 1% salt concentration, 500 MPa/10 °C/10 min, and 40 °C/2 h; PS2: 2% salt concentration, 500 MPa/10 °C/10 min, and 40 °C/2 h; PC1: 1% salt concentration, 500 MPa/10 °C/10 min, and 90 °C/30 min; PC2: 2% salt concentration, 500 MPa/10 °C/10 min, and 90 °C/30 min; SP1: 1% salt concentration, 40 °C/2 h min, and 500 MPa/10 °C/10 min; SP2: 2% salt concentration, 40 °C/2 h, and 500 MPa/10 °C/10 min.
Figure 4. SEM images of pangasius gels containing 1% and 2% salt under different high-pressure and thermal conditions. HIGs: conventional heat-induced gels; PS1: 1% salt concentration, 500 MPa/10 °C/10 min, and 40 °C/2 h; PS2: 2% salt concentration, 500 MPa/10 °C/10 min, and 40 °C/2 h; PC1: 1% salt concentration, 500 MPa/10 °C/10 min, and 90 °C/30 min; PC2: 2% salt concentration, 500 MPa/10 °C/10 min, and 90 °C/30 min; SP1: 1% salt concentration, 40 °C/2 h min, and 500 MPa/10 °C/10 min; SP2: 2% salt concentration, 40 °C/2 h, and 500 MPa/10 °C/10 min.
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Table 1. Treatment conditions for the experiments.
Table 1. Treatment conditions for the experiments.
TreatmentSalt ConcentrationConditions
1%2%
HIG 0.1 MPa/90 °C/30 min.
Pressurized–Cooking (PC)PC1PC2500 MPa/10 °C/10 min then heating at 0.1 MPa/90 °C/30 min.
Pressurized–Setting (PS)PS1PS2500 MPa/10 °C/10 min then heating at 0.1 MPa/40 °C/2 h
Setting–Pressurized (SP)SP1SP20.1 MPa/40 °C/2 h then heating at 500 MPa/<10 °C/10 min.
Pressurized–Cooking (PC)PC1PC2500 MPa/10 °C/10 min then heating at 0.1 MPa/90 °C/30 min.
Table 2. TPC of pangasius gels at 1% and 2% salt concentrations after different HPP and setting treatments.
Table 2. TPC of pangasius gels at 1% and 2% salt concentrations after different HPP and setting treatments.
TreatmentTotal Microbial Count (log CFU/g)
HIG2.33 ± 0.33 a
PC11.58 ± 0.26 b
PC21.51 ± 0.30 b
PS12.32 ± 0.29 a
PS22.36 ± 0.28 a
SP12.41 ± 0.43 a
SP22.23 ± 0.26 a
Different letters (a, b) indicate significant differences (p < 0.05).
Table 3. Effect of different HPP and thermal conditions on the color of pangasius gels with 1% and 2% salt.
Table 3. Effect of different HPP and thermal conditions on the color of pangasius gels with 1% and 2% salt.
TreatmentWhiteness∆E
HIG60.48 ± 0.40 a
PC163.62 ± 0.93 b7.77 ± 0.39 a
PC263.48 ± 0.47 b7.68 ± 1.18 a
PS161.12 ± 0.76 a2.65 ± 1.07 b
PS261.13 ± 0.55 a2.18 ± 0.83 b
SP158.29 ± 0.25 c2.51 ± 1.14 b
SP259.26 ± 0.41 d2.86 ± 0.98 b
Values in the same column with different letters (a, b, c, and d) are significantly different (p < 0.05).
Table 4. Changes in the mechanical characteristics of pangasius gels containing 1% and 2% salt under various HPP and thermal conditions.
Table 4. Changes in the mechanical characteristics of pangasius gels containing 1% and 2% salt under various HPP and thermal conditions.
TreatmentsGel Strength (N.mm)Hardness (N)Springiness (mm)
HIG391.24 ± 21.44 a7.36 ± 0.36 ae0.87 ± 0.02 a
PC1496.72 ± 41.84 b9.62 ± 1.24 b0.87 ± 0.03 a
PC2501.26 ± 47.38 b10.14 ± 1.27 b0.89± 0.02 ac
PS1436.74 ± 24.35 a8.33 ± 0.88 ad0.91 ± 0.01 bc
PS2443.52 ± 32.06 a9.02 ± 0.72 bd0.96 ± 0.01 b
SP1319.79 ± 50.25 c5.87 ± 0.67 c0.86 ± 0.01 a
SP2338.34 ± 17.25 c6.31 ± 0.39 ce0.87 ± 0.02 a
Values within a column not sharing a common letter are significantly different (p < 0.05) based on Tukey’s HSD test.
Table 5. Secondary structure composition (%) of pangasius gels containing 1% and 2% salt, determined through FTIR self-deconvolution under different high-pressure and thermal conditions.
Table 5. Secondary structure composition (%) of pangasius gels containing 1% and 2% salt, determined through FTIR self-deconvolution under different high-pressure and thermal conditions.
Treatmentα-Helix (%)β-Sheet (%)β-Turn (%)Random Coil Structure (%)Aromatic Side Chain
HIG23.61 ± 0.83 a 27.76 ± 3.26 a 20.37 ± 2.83 a 9.47 ± 1.48 a18.75 ± 1.53 a
PS124.99 ± 2.42 ab26.17 ± 4.59 a 22.22 ± 2.12 a 7.04 ± 0.54 b 19.54 ± 0.21 a
PS225.08 ± 3.03 ab25.69 ± 3.57 a 23.40 ± 3.04 a 6.78 ± 0.99 b19.04 ± 1.74 a
PC128.04 ± 0.91 b25.49 ± 0.92 a20.69 ± 2.17 a 6.69 ± 0.92 b 19.05 ± 4.18 a
PC228.09 ± 0.51 b26.13 ± 3.31 a20.54 ± 3.46 a7.38 ± 0.67 b17.83 ± 4.71 a
SP125.37 ± 3.76 ab26.97 ± 4.20 a 21.49 ± 2.30 a6.62 ± 0.49 b19.54 ± 2.22 a
SP225.96 ± 3.12 ab25.99 ± 6.30 a 22.79 ± 1.90 a7.38 ± 0.77 b17.86 ± 4.04 a
Different letters (a, b) in the same column indicate significant differences (p < 0.05). HIGs: conventional heat-induced gels; PS1: 1% salt concentration, 500 MPa/10 °C/10 min, and 40 °C/2 h; PS2: 2% salt concentration, 500 MPa/10 °C/10 min, and 40 °C/2 h; PC1: 1%, salt concentration, 500 MPa/10 °C/10 min, and 90 °C/30 min; PC2: 2% salt concentration, 500 MPa/10 °C/10 min, and 90 °C/30 min; SP1: 1% salt concentration, 40 °C/2 h min, and 500 MPa/10 °C/10 min; SP2: 2% salt concentration, 40 °C/2 h, and 500 MPa/10 °C/10 min.
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Truong, B.Q.; Vo, B.T.T.; Buckow, R.; Hoang, V.C. Changes in the Physicochemical Properties of Reduced Salt Pangasius (Pangasianodon hypophthalmus) Gels Induced by High Pressure and Setting Treatment. Sci 2025, 7, 99. https://doi.org/10.3390/sci7030099

AMA Style

Truong BQ, Vo BTT, Buckow R, Hoang VC. Changes in the Physicochemical Properties of Reduced Salt Pangasius (Pangasianodon hypophthalmus) Gels Induced by High Pressure and Setting Treatment. Sci. 2025; 7(3):99. https://doi.org/10.3390/sci7030099

Chicago/Turabian Style

Truong, Binh Q., Binh T. T. Vo, Roman Buckow, and Van Chuyen Hoang. 2025. "Changes in the Physicochemical Properties of Reduced Salt Pangasius (Pangasianodon hypophthalmus) Gels Induced by High Pressure and Setting Treatment" Sci 7, no. 3: 99. https://doi.org/10.3390/sci7030099

APA Style

Truong, B. Q., Vo, B. T. T., Buckow, R., & Hoang, V. C. (2025). Changes in the Physicochemical Properties of Reduced Salt Pangasius (Pangasianodon hypophthalmus) Gels Induced by High Pressure and Setting Treatment. Sci, 7(3), 99. https://doi.org/10.3390/sci7030099

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