Quality Evaluation of Polygonatum cyrtonema Hua Based on UPLC-Q-Exactive Orbitrap MS and Electronic Sensory Techniques with Different Numbers of Steaming Cycles

In this study, electronic sensory techniques were employed to comprehensively evaluate the organoleptic quality, chemical composition and content change rules for Polygonatum cyrtonema Hua (PCH) during the steaming process. The results were subjected to hierarchical cluster analysis (HCA), principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA). These analyses revealed, from a sensory product perspective, overall differences in colour, odour and taste among the samples of PCH with different numbers of steaming cycles. Using the UPLC-Q-Exactive Orbitrap MS technique, 64 chemical components, including polysaccharides, organic acids, saponins and amino acids were detected in PCH before and after steaming. The sensory traits were then correlated with the chemical composition. From the perspectives of sensory traits, chemical composition, and multi-component index content, it was preliminarily deduced that carrying out five cycles of steaming and sun-drying was optimal, providing evidence for the quality evaluation of PCH during the steaming process.


Introduction
Polygonatum cyrtonema Hua (PCH), belonging to the family Asparagales, is a medicinal and edible perennial plant.Plants of the same genus, including P. kingianum and P. cyrtonema, have also been used as substitutes for P. Sibiricum [1].The functions of PCH include nourishing the liver and kidneys and promoting longevity [2,3].In recent years, many scholars have discovered that PCH contains polysaccharides, steroidal saponins, flavonoids, alkaloids, and other ingredients [4][5][6][7].PCH needs to be concocted before it can be used in medicine.Its main purposes are to reduce toxicity, increase effectiveness, eliminate throat irritation, enhance the function of tonifying the spleen, moistening the lungs, benefiting the kidneys, and enhancing biological activity [6,7].
There are numerous records on the methods for processing PCH, including single steaming, wine steaming, and nine cycles of steaming and sun-drying [8].The "Nine Steaming Nine Sun-drying" method has appeared most frequently in successive herbal medical books, and has been widely used in the history of PCH processing methods.In ancient times, the determination of the endpoint of the "Nine Steaming Nine Sundrying" process for PCH was performed using the naked eye to observe the changes in characteristics during the steaming process.The decision on how many cycles of steaming Foods 2024, 13, 1586 3 of 20

Appearance Traits and Sensory Evaluation
The colour, texture, odour, and taste profiles of the products were rated separately from both medicinal and culinary perspectives, in conjunction with the sensory evaluation of the food.The assessment panel consisted of 10 members who had been professionally trained.Referring to the criteria in Table 1, each steamed sample was placed on a white background.Its colour, lustre, and texture were observed under natural light, and its smell was evaluated to determine if there were any off odours.Afterwards, the taste was evaluated, and the PCH was scored for appearance properties and sensory evaluation with a total score of 100.The sensory properties were then documented and described.

Electronic Eye Detection
The dried herb samples were powdered, and then passed through a No. 4 sieve.After stabilising the power, the lens exposure and focal length were corrected and calibrated with a chromaticity plate placed in the tray, using a 5 mm lens with top and bottom illumination.A specific amount of sieved powder from each PCH sample was spread on a slide.The slide was then placed on the white-bottom plate of the instrument to capture images.The position was adjusted, and pictures were taken in parallel three times.The chromaticity space parameters of the samples during the steaming process of PCH are represented by L* (L* = Luminance, 100 means white, 0 means black), a* (+a* means red, −a* means green), b* (+b* means yellow, −b* means blue).The ∆E* value is calculated according to the following equation:

Electronic Nose Detection
The PEN3 electronic nose sensor response reflects the adsorbed gas state of chemical molecules and subsequent surface chemical reactions or physical effects resulting from changes in resistivity and conductivity [19].The response value is calculated as G/G0.If G/G0 ≤ 1, it means that the sample has no response to this sensor.The characteristics are detailed in Table 2.Each sample was taken, placed in a 50 mL centrifuge tube, sealed with a film, and left for 30 min to enrich before testing.The electronic nose sampling time was 1 s per group, the sensor self-cleaning time was 80 s, the sensor zeroing time was 5 s, the injection flow rate was 400 mL/min, and the analysis sampling time was 100 s.Three parallels were made for each sample, and the stable signal obtained at 80 s from the sensor was taken for analysis.The electronic tongue detected eight attributes of PCH samples: sourness, bitterness, astringency, freshness, saltiness, and sweetness.Six sensors, C00, AE1, CA0, CT0, AAE, and GL1, corresponded to bitterness, astringency, sourness, saltiness, freshness, and sweetness, respectively, in addition to bitter aftertaste, astringent aftertaste, and richness.The types of electronic tongue sensor responses are shown in Table 3.A measure of 1.5 g of sample powder was weighed in a centrifuge tube, 50 mL of distilled water was added to soak for 30 min, and the sample was placed into a sonicator and sonicated for 1 h.After sonication, the sample was centrifuged for 10 min at a speed of 4000 r/min, and the supernatant was collected.A measure of 50 mL of distilled water was added, the extraction was repeated once following the above conditions, the supernatant was centrifuged, and the obtained supernatant was combined twice.The sensor was first cleaned in the cleaning solution for 90 s.The reference solution was then cleaned for 120 s, followed by cleaning with another reference solution for 120 s.The sensor was zeroed at the equilibrium position for 30 s.The test was cycled four times, the first cycle was removed, and the average of data from the last three times were taken as the test results.
All experiments using the electronic eye, electronic nose and electronic tongue needed to be measured three times in parallel and averaged.Origin 2021, SIMCA 14.1 and IBM SPSS 26.0 were used for image plotting and data processing.
The MS system was based on a Thermo Fisher Scientific Orbitrap Exploris 120 mass spectrometer (workstation Xcalibur 4.3), and the Full MS-dd-MS2 scan mode (m/z 100-1500 Da) was used, with data acquired under positive and negative ion conditions, resulting in IDA-based acquisition modes of MS as well as MS/MS data.The sheath gas flow rate was 35 Arb, the auxiliary gas flow rate was 15 Arb, the ion transfer tube temperature was 350 • C, the vaporiser temperature was 350 • C, the full MS resolution was 60,000, the MS/MS resolution was 15,000, the collision energy was 16/32/48 (NCE mode), and the spray voltage was either 4 kV (+) or 3.8 kV (−).
Based on the Chinese and English literature, and querying Chemspider, Pubchem, TCMSP, HMDB, KEGG, MassBank and other online databases, we searched for the reported chemical constituents in PCH and established a database of chemical constituents of PCH, including their compound names, molecular formulae, molecular weights, and chemical structures.The molecular formulae of the chromatographic peaks were deduced using the Thermo Xcalibur 2.1 workstation, and the raw data were imported using XCMS software for retention time correction, peak identification, peak extraction, peak integration, and peak alignment, with the mass spectral deviation range of δ ≤ 5 ppm.The preprocessed mass spectral data information was compared with the secondary mass spectral fragmentation ions of the database and the chemical formula of the compound, and the chemical formulae of the compound were identified.We also searched for the possible chemical formulae and cleavage fragments of the compounds in combination with the literature and repeatedly compared and verified the identified compositions.

Data Statistics and Analysis
Data are expressed as the mean ± standard deviation (SD) of 3 independent experiments; statistical analysis was performed with SPSS Statistics 26 software, using least significant difference (LSD) multiple comparisons, principal component analysis (PCA), and orthogonal partial least squares discriminant analysis (OPLS-DA).Significant difference between different groups was considered at p < 0.05.Correlation analysis was performed using the Pearson correlation coefficient.Plots were performed using Origin 2022, Simca 14.1.

Appearance Properties and Organoleptic Evaluation of PCH with Different Numbers of Steaming Cycles
The appearance of PCH after industrial steaming is documented in Figure 1 which clearly illustrates the yellow-white colour of the multifloral yellow essence before steaming (S0).The colour changed from brownish brown to black as a result of between one and five cycles of steaming (S1-S5).After five cycles of steaming and sun-drying, the PCH samples all appeared uniformly black, with the naked eye gradually unable to distinguish the difference; however, the subsequent colour differences also needed to be detected using the electronic eye for the colour test.The sensory scores and evaluation of descriptive results are shown in Table 4. From Table 4, it can be observed that as the number of steaming cycles increased, the sensory scores of PCH showed a pattern of initially increasing and then decreasing.The scores of S0 and S1 of PCH were below 60, indicating poor sensory evaluation.With the change in the number of steaming cycles, the scores gradually increased, and the flavour improved over time.Notably, the scores of PCH S5-S8 were higher, and the difference was not significant.However, the scores of No. S9-S11 PCH gradually decreased with the increasing number of steaming cycles, and the organoleptic evaluation results deteriorated over time.As can be seen from Table 4, the texture of PCH in the steaming process changed from hard to soft and sticky; raw products did not have a distinct smell, but as the number of steaming cycles increased, the smell gradually became stronger, and then a burnt aroma or even burnt flavour was exuded.Simultaneously, the overall taste was changed, and the initial bitter and astringent numbness of the tongue was gradually eliminated, with the sweetness enhanced.
evaluation results deteriorated over time.As can be seen from Table 4, the texture of PCH in the steaming process changed from hard to soft and sticky; raw products did not have a distinct smell, but as the number of steaming cycles increased, the smell gradually became stronger, and then a burnt aroma or even burnt flavour was exuded.Simultaneously, the overall taste was changed, and the initial bitter and astringent numbness of the tongue was gradually eliminated, with the sweetness enhanced.In the first stage, the colour of PCH was found to change gradually from yellowish white to blackish black with different numbers of steaming cycles, but in the later stage, the change in colour was not obvious, and the recognition of the colour change by the naked eye was reduced.As can be seen from Figure 2a, a* and b* are both positive values, representing that the external colour of PCH is generally between yellow and red.As the number of steaming cycles increased, the a* value showed a gradual increase, indicating  In the first stage, the colour of PCH was found to change gradually from yellowish white to blackish black with different numbers of steaming cycles, but in the later stage, the change in colour was not obvious, and the recognition of the colour change by the naked eye was reduced.As can be seen from Figure 2a, a* and b* are both positive values, representing that the external colour of PCH is generally between yellow and red.As the number of steaming cycles increased, the a* value showed a gradual increase, indicating that the colour of the sample gradually changed to red, while the b* value gradually decreased, indicating that the orange-yellow colour gradually faded away.The S0 sample had the highest L*, which gradually decreased with the number of steaming cycles, indicating a gradual decrease in brightness, which manifested as a deepening of the brown colour.The larger the ∆E* value, the larger the colour difference; conversely, the smaller the value, the smaller the measured colour difference.Taking the raw PCH S0 as a reference, S1 had the lowest value of ∆E*.The values of ∆E* of the samples all increased significantly with the number of steaming cycles, indicating that the samples steamed once were closest to the colour of the raw product.In addition, the fluctuation of ∆E* values of S5-S11 of PHC was small, indicating that the change in its blackish colour was gradually stabilised.
the value, the smaller the measured colour difference.Taking the raw PCH S0 as a reference, S1 had the lowest value of ∆E*.The values of ∆E* of the samples all increased significantly with the number of steaming cycles, indicating that the samples steamed once were closest to the colour of the raw product.In addition, the fluctuation of ∆E* values of S5-S11 of PHC was small, indicating that the change in its blackish colour was gradually stabilised.

Changes in Odour of PCH with Different Numbers of Steaming Cycles
As can be seen from Figure 2b, the response values of the 10 sensors show significant differences with the increase in the amount of evaporation, and the differences are mainly reflected in the four sensors W1W, W2W, W5S, and W1S.No response or a low response was found on W1C, W3C, W6S, W5C, W2S, and W3S, which can be ignored.The response values of W1W, W2W, W5S, and W1S were higher, and the response values were all greater than 1, which represented the main components of the odour of PCH.It is presumed that the differences in the odour of PCH during industrial steaming are mainly a result of the differences in volatiles such as terpenes, inorganic sulphides, aromatics, nitrogen oxides, alkanes, etc.The response values of the four sensors of S0 were all low, less than 2, indicating that raw PCH contained less odour information.The response values of W1W, W2W and W5S increased with the number of steaming cycles, while W1S exhibited a decreasing trend, until the response values of S11 PCH were significantly higher than those of the samples on the W1W, W2W, W5S and W1S sensors.It is assumed that with the increase in the number of steaming cycles, the high temperature leads to the continuous decomposition of proteins, producing sulphides, methane and nitrogen oxides.Therefore, the burnt aroma of the PCH after steaming may be attributed to these components.

Changes in Flavour of PCH with Different Numbers of Steaming Cycles
The electronic tongue test simulates the state of the human mouth when only saliva is present and uses a reference solution to determine taste values.Taste-free points exist for sour and salty flavours, with −6 for salty, −13 for sour, and 0 for the rest of the tastes.When a specific taste response value is less than the no-taste point, it indicates the taste does not exist, and vice versa, the corresponding taste is present.As can be seen from Figure 2c, the order of response values in S0 was as follows: sweetness > freshness > bitterness > astringency.With the increase in the number of steaming cycles, the four flavour response values showed a gradual declining trend.Six cycles of steaming did not appear to significantly reduce this change.The response values for bitter aftertaste, astringent

Changes in Odour of PCH with Different Numbers of Steaming Cycles
As can be seen from Figure 2b, the response values of the 10 sensors show significant differences with the increase in the amount of evaporation, and the differences are mainly reflected in the four sensors W1W, W2W, W5S, and W1S.No response or a low response was found on W1C, W3C, W6S, W5C, W2S, and W3S, which can be ignored.The response values of W1W, W2W, W5S, and W1S were higher, and the response values were all greater than 1, which represented the main components of the odour of PCH.It is presumed that the differences in the odour of PCH during industrial steaming are mainly a result of the differences in volatiles such as terpenes, inorganic sulphides, aromatics, nitrogen oxides, alkanes, etc.The response values of the four sensors of S0 were all low, less than 2, indicating that raw PCH contained less odour information.The response values of W1W, W2W and W5S increased with the number of steaming cycles, while W1S exhibited a decreasing trend, until the response values of S11 PCH were significantly higher than those of the samples on the W1W, W2W, W5S and W1S sensors.It is assumed that with the increase in the number of steaming cycles, the high temperature leads to the continuous decomposition of proteins, producing sulphides, methane and nitrogen oxides.Therefore, the burnt aroma of the PCH after steaming may be attributed to these components.

Changes in Flavour of PCH with Different Numbers of Steaming Cycles
The electronic tongue test simulates the state of the human mouth when only saliva is present and uses a reference solution to determine taste values.Taste-free points exist for sour and salty flavours, with −6 for salty, −13 for sour, and 0 for the rest of the tastes.When a specific taste response value is less than the no-taste point, it indicates the taste does not exist, and vice versa, the corresponding taste is present.As can be seen from Figure 2c, the order of response values in S0 was as follows: sweetness > freshness > bitterness > astringency.With the increase in the number of steaming cycles, the four flavour response values showed a gradual declining trend.Six cycles of steaming did not appear to significantly reduce this change.The response values for bitter aftertaste, astringent aftertaste and richness were all lower in the samples.There was no significant change in the response values with an increase in the number of steaming cycles.The sour flavour did not show a response in S0-S5, but did show a response value in S6.Furthermore, the response value increased as the number of steaming cycles increased.The aforementioned changes suggest that the unpleasant taste decreased after repeated steaming, while the carbonyl-ammonia condensation reaction occurred between aldoses and ketoses, which are sweet sugars, and amino acids and proteins, which have fresh flavours [20].

Statistical Analyses
Hierarchical cluster analysis (HCA) [21] was conducted using the information from the electronic eye, nose, and tongue indicators of PCH samples with different numbers of steaming cycles.The cluster analyses among the samples are shown in Figure 3.The results showed that when the distance was 10, the samples were divided into two main classes.S0 was clustered into one major class alone, while S1, S2, S3, and S4 were clustered into another major class.Additionally, S5, S6, S7, S8, S9, S10, and S11 were clustered into a separate major class.Further analysis shows that when the distance is 5, the samples are divided into five classes in total: S0; S1; S2, S3, and S4; S5, S6, S7, and S8; and S9, S10, and S11.The results indicate that HCA can determine whether PCH has been steamed or not based on the organoleptic information indexes, and it can group together samples with similar organoleptic information during the steaming process of PCH.However, HCA cannot provide more detailed information regarding the differences between the samples of PCH and the organoleptic indexes.This necessitates multivariate statistical analysis, which combines principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA).
the response values with an increase in the number of steaming cycles.The sour flavour did not show a response in S0-S5, but did show a response value in S6.Furthermore, the response value increased as the number of steaming cycles increased.The aforementioned changes suggest that the unpleasant taste decreased after repeated steaming, while the carbonyl-ammonia condensation reaction occurred between aldoses and ketoses, which are sweet sugars, and amino acids and proteins, which have fresh flavours [20].

Statistical Analyses
Hierarchical cluster analysis (HCA) [21] was conducted using the information from the electronic eye, nose, and tongue indicators of PCH samples with different numbers of steaming cycles.The cluster analyses among the samples are shown in Figure 3.The results showed that when the distance was 10, the samples were divided into two main classes.S0 was clustered into one major class alone, while S1, S2, S3, and S4 were clustered into another major class.Additionally, S5, S6, S7, S8, S9, S10, and S11 were clustered into a separate major class.Further analysis shows that when the distance is 5, the samples are divided into five classes in total: S0; S1; S2, S3, and S4; S5, S6, S7, and S8; and S9, S10, and S11.The results indicate that HCA can determine whether PCH has been steamed or not based on the organoleptic information indexes, and it can group together samples with similar organoleptic information during the steaming process of PCH.However, HCA cannot provide more detailed information regarding the differences between the samples of PCH and the organoleptic indexes.This necessitates multivariate statistical analysis, which combines principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA).The dataset composed of three intelligent sensory technology indicators was fitted with multi-source information and analysed; it can be seen from Figure 4a that the R 2 X is 0.996, representing the rate of explanation of the dimensionality-reduced data compared to the original data.The closer the value is to 1, the more desirable it is, and a value greater than 0.5 indicates that the model is more effective.The sum of PC1 and PC2 reached 84.3%, representing 84.3% of the information from all indicators.The greater the distance between samples, the greater the overall sensory difference.Principal component analysis revealed differences in colour, odour and taste among the steamed products of PCH.S0 is Foods 2024, 13, 1586 9 of 20 outside the confidence ellipse and is an outlier, indicating that the organoleptic information indexes of the raw sample differ greatly from those of the rest of the samples, while S9, S10, and S11 are clustered, indicating that the organoleptic information of the three samples is, to a certain extent, similar.In addition, this study also compared the models of single techniques for sensory quality evaluation of PCH; the results are shown in Figure 4b-d.The R 2 X in the PCA of e-eye samples was 0.985; in the PCA of e-nose samples, it was 0.995; in the PCA of e-tongue samples, it was 0.917.
representing 84.3% of the information from all indicators.The greater the distance between samples, the greater the overall sensory difference.Principal component analysis revealed differences in colour, odour and taste among the steamed products of PCH.S0 is outside the confidence ellipse and is an outlier, indicating that the organoleptic information indexes of the raw sample differ greatly from those of the rest of the samples, while S9, S10, and S11 are clustered, indicating that the organoleptic information of the three samples is, to a certain extent, similar.In addition, this study also compared the models of single techniques for sensory quality evaluation of PCH; the results are shown in Figure 4b-d.The R X 2 in the PCA of e-eye samples was 0.985; in the PCA of e-nose samples, it was 0.995; in the PCA of e-tongue samples, it was 0.917.The outliers (S0) were observed in the PCA, and the OPLS-DA was performed after removing the outliers.As shown in Figure 5a, after excluding S0, the cumulative statistics of the OPLS-DA model were as follows: R 2 X = 0.999, R 2 Y = 0.942, and Q 2 = 0.83.All values exceeded 0.5, suggesting an improved predictive capability of the model for the sensory information indices of the PCH steaming process.To further determine the stability of the model, the replacement test (n = 200) was used to validate the model.As shown in Figure 5b, all the green R2 values and blue Q2 values on the left side are lower than the original points on the right side.The blue regression line for the Q2 points intersects the vertical axis, indicating the validity of the original model.Based on the variable importance projection (VIP) values used to assess the variability of sensory information during the steaming process of PCH, it can be observed from Figure 5c that 11 indicators, namely, richness, W1S, a*, W3S, W6S, bitterness, astringency, bitter aftertaste, W1W, W5S, and W5C, were identified as having the most significant impact on the organoleptic evaluations of samples before and after PCH steaming, based on the criterion that the VIP value was >1.identified as having the most significant impact on the organoleptic evaluations of samples before and after PCH steaming, based on the criterion that the VIP value was >1.

Identification of Chemical Constituents of PCH with Different Numbers of Steaming Cycles
The aqueous extract of PCH was analysed using the UPLC-Q-Exactive Orbitrap MS technique with different numbers of steaming cycles, and TIC plots of PCH aqueous extract were obtained in positive and negative ion modes (ion flow diagram in Supplementary File S1), which are shown in Figure 6.A total of 64 chemical components were identified by preprocessing the mass spectrometry data information, matching it with the database and combining it with fragment ion information from the literature.Among them, there were nine organic acids, eight flavonoids, seven alkaloids, eight amino acids, seven saponins, and twenty-five other compounds.The cleavage information of the identified compounds is shown in Table 5.

Identification of Chemical Constituents of PCH with Different Numbers of Steaming Cycles
The aqueous extract of PCH was analysed using the UPLC-Q-Exactive Orbitrap MS technique with different numbers of steaming cycles, and TIC plots of PCH aqueous extract were obtained in positive and negative ion modes (ion flow diagram in Supplementary File S1), which are shown in Figure 6.A total of 64 chemical components were identified by preprocessing the mass spectrometry data information, matching it with the database and combining it with fragment ion information from the literature.Among them, there were nine organic acids, eight flavonoids, seven alkaloids, eight amino acids, seven saponins, and twenty-five other compounds.The cleavage information of the identified compounds is shown in Table 5.   7 shows that there is no obvious difference in the types of chemical constituents before and after PCH steaming, but the relative content of each constituent varies greatly in the middle (detailed identification and analysis of compositions in Supplementary File S2).The total amount of saponins gradually decreased with the increase in the number of steaming cycles, possibly due to high-temperature cleavage during the steaming process and the formation of secondary glycosides or glycosides.The relative content of amino acids and organic acids also showed a decreasing trend, possibly attributed to their solubility in water.The structure of these compounds is easily damaged, decomposed, or denatured at high temperatures.Flavonoids and alkaloids exhibited a pattern of initial increase followed by a decline, likely attributed to the elevated temperature during the steaming process, facilitating dissolution.However, with repeated steaming, glycosides may undergo highenergy bombardment, leading to glycosyl fracture.The relative contents of other small molecules, such as fatty acids and phenylpropanoids, showed a significant increasing trend.ing the steaming process, facilitating dissolution.However, with repeated steaming, glycosides may undergo high-energy bombardment, leading to glycosyl fracture.The relative contents of other small molecules, such as fatty acids and phenylpropanoids, showed a significant increasing trend.

Conclusions
The results of this study showed that, with an increase in the number of steaming cycles, PCH gradually changed from yellow-white to brown.The odour response value increased after steaming, and the scent gradually became more intense, displaying sweet and smoky notes.Sweetness, freshness, bitterness and astringency gradually decreased,

Figure 2 .
Figure 2. Sensory evaluation results of PCH industrialised steaming.(a) Electronic eye radar analysis of PCH industrialised steaming; (b) electronic nose radar analysis of PCH industrialised steaming; (c) electronic tongue radar analysis of PCH industrialised steaming.

Figure 2 .
Figure 2. Sensory evaluation results of PCH industrialised steaming.(a) Electronic eye radar analysis of PCH industrialised steaming; (b) electronic nose radar analysis of PCH industrialised steaming; (c) electronic tongue radar analysis of PCH industrialised steaming.

Figure 3 .
Figure 3. Cluster analysis chart of PCH after industrialised steaming.Figure 3. Cluster analysis chart of PCH after industrialised steaming.

Figure 3 .
Figure 3. Cluster analysis chart of PCH after industrialised steaming.Figure 3. Cluster analysis chart of PCH after industrialised steaming.

Figure 6 .
Figure 6.Total ion chromatogram of PCH extraction solution in both positive ion (a) and ne ion (b) modes.

Figure 6 .
Figure 6.Total ion chromatogram of PCH extraction solution in both positive ion (a) and negative ion (b) modes.

Figure 7 .
Figure 7. Changes in chemical components of PCH extraction solution in the process of industrial steaming.

Figure 7 .
Figure 7. Changes in chemical components of PCH extraction solution in the process of industrial steaming.

Figure 8 .
Figure 8. Correlation matrix heat map.Heat map of Spearman correlation between odour and HPLC analysis for each biomarker for the overall population analysed.* indicates significant differences between instrumental and odour parameters according to Pearson correlation coefficient (p ≤ 0.05).

Figure 8 .
Figure 8. Correlation matrix heat map.Heat map of Spearman correlation between odour and HPLC analysis for each biomarker for the overall population analysed.* indicates significant differences between instrumental and odour parameters according to Pearson correlation coefficient (p ≤ 0.05).

Foods 2024 , 22 Figure 9 .
Figure 9. Correlation matrix heat map.Heat map of Spearman correlation between flavour and HPLC analysis between each biomarker for the overall population analysed.* indicates significant differences between instrumental and flavour parameters according to Pearson correlation coefficient (p ≤ 0.05).

Figure 9 .
Figure 9. Correlation matrix heat map.Heat map of Spearman correlation between flavour and HPLC analysis between each biomarker for the overall population analysed.* indicates significant differences between instrumental and flavour parameters according to Pearson correlation coefficient (p ≤ 0.05).

Table 1 .
The sensory evaluation criteria of PCH.

Table 2 .
Sensitive substance type of each sensor.

Table 3 .
Electronic tongue sensor information table.
Note: "-" is a taste sensor that is not involved.

Table 4 .
Sensory evaluation description of PCH industrialised steaming.
3.1.2.Variation in Colour Parameters of PCH with Different Numbers of Steaming Cycles

Table 4 .
Sensory evaluation description of PCH industrialised steaming.
3.1.2.Variation in Colour Parameters of PCH with Different Numbers of Steaming Cycles

Table 5 .
Identification of chemical components in extraction solution.