Review Reports

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Comments to the Authors

1. Check the font of the title of the article
2. The title and text refer to "batter-breaded chicken strips", but the methodology describes dipping chicken strips in a liquid batter without a dry breadcrumb coating step (Section 2.2).
3. Can the authors articulate more sharply what distinct mechanistic insights this study offers beyond confirming standard lipid oxidation and Maillard reaction trends?
4. The introduction highlights health concerns regarding high oil content, but the study does not test any low-fat strategies or pretreatments other than varying temperature.
5. The batter contains a complex blend of 20% wheat flour, 16.4% sweet potato starch, 4% kudzu root starch, and 0.6% baking starch. What was the functional rationale for combining three different starch sources in these precise proportions? 
6. Section 2.2 describes immersing chicken strips in batter for 10 s and draining for 2–5 s. How was coating pick-up weight controlled and verified across replicates to ensure uniform thickness before frying?
7. What type of tertiary rapeseed oil was used, and how frequently was the frying oil replenished or monitored for total polar compounds to prevent oxidative degradation from confounding results across multi-temperature trials? 
8. Section 2.5 states that fried strips were minced into powder for fat analysis, and Section 2.6 mentions uniform crushing for E-nose evaluation. Were the crust and core separated for chemical and volatile analyses, or was the whole strip analyzed as a composite? 
9. Table 2 presents instrumental springiness (mm) alongside "sensory springiness (%)". How was "sensory springiness" quantitatively evaluated by the 10-member panel, and why does it follow a different trend than instrumental springiness?
10. Section 3.4.2 discusses triethylenediamine-M and D as byproducts of Maillard reactions and notes that blank runs ruled out column contamination. Is triethylenediamine a recognized food volatile or could it be an artifact of plasticizer migration or packaging interaction
11. 3-methylbutan-1-ol (isoamyl alcohol) was strongly negatively correlated with sensory scores. Can the authors clarify whether its formation is driven predominantly by leucine degradation in the chicken meat or amino acid reactions in the wheat/starch batter?

Author Response

Response to Reviewer 1

Summary
We sincerely thank the reviewer for the careful reading and constructive comments. All revisions have been made in the resubmitted manuscript and are marked in red.

 

Point-by-point response to Comments and Suggestions for Authors

Comment 1: Check the font of the title of the article.

Response 1: Thank you for pointing this out. We have standardized the title font according to the MDPI journal template. No textual change was made to the title itself. (Title, Page 1, Line 1)

 

Comment 2: The title and text refer to "batter-breaded chicken strips", but the methodology describes dipping chicken strips in a liquid batter without a dry breadcrumb coating step (Section 2.2).

Response 2: We completely agree with the reviewer. Since our process involves only a liquid batter and no dry breadcrumb coating, the term "breaded" is indeed inaccurate. We have replaced "batter-breaded" with "batter-coated" throughout the entire manuscript, including the title, abstract, keywords, and main text. (Title, Page 1, Line 1; Section 2.2 heading, Page 3, Line 114)

 

Comment 3: Can the authors articulate more sharply what distinct mechanistic insights this study offers beyond confirming standard lipid oxidation and Maillard reaction trends?

Response 3: We thank the reviewer for this incisive comment. We agree that simply confirming standard trends provides limited novelty. We have therefore significantly strengthened the mechanistic discussion in the revised manuscript to articulate three distinct, matrix-specific insights:
(1) The crust acts as a temperature-dependent diffusion barrier decoupling surface and core chemistry. We observed that individual lipid-oxidation products did not co-vary with temperature: hexanal-M decreased above 170 °C, whereas butyraldehyde-M increased continuously. This divergence is attributed to the rapid formation of a dense gelatinized crust at higher temperatures, which limits oil penetration and restricts the substrate available for hexanal formation.
(2) The two reaction pathways compete for a shared, temperature-sensitive pool of precursors and water. The relative contents of pyrazines, amines, and ketones increased with temperature, whereas aldehydes, alcohols, acids, esters, and furans declined. We propose that the ~170 °C inflection—where sensory score and oil content peak—marks the point at which crust consolidation begins to suppress oil-mediated lipid oxidation while Maillard chemistry continues to accelerate.
(3) Specific volatile markers map onto distinct biochemical routes. 2-Methylpyrazine and cinnamyl alcohol track the Maillard/amino-acid route and correlate positively with sensory score; 3-methylbutan-1-ol tracks branched-chain amino acid degradation and correlates negatively.
These points are now explicitly stated in Section 3.1 (Page 6, Lines 242–245), Section 3.4.4 (Page 15, Lines 471–476), and Section 3.4.9 (Page 21, Lines 578–583), and are reflected in the Conclusions (Page 23, Lines 603–607).

 

Comment 4: The introduction highlights health concerns regarding high oil content, but the study does not test any low-fat strategies or pretreatments other than varying temperature.

Response 4: We agree with the reviewer. To avoid overstating the scope of our study, we have added a clarifying sentence at the end of the Introduction. It explicitly states that the present study does not evaluate low-fat pretreatments, but rather examines how frying temperature alone governs the balance between oil uptake, texture, and flavor, thereby providing a basis for subsequent low-fat strategy development. (Introduction, Page 3, Lines 88–92)

 

Comment 5: 5.The batter contains a complex blend of 20% wheat flour, 16.4% sweet potato starch, 4% kudzu root starch, and 0.6% baking starch. What was the functional rationale for combining three different starch sources in these precise proportions?

Response 5: We thank the reviewer for this question. This formulation was derived from our previous optimization study [10] using response surface–principal component analysis. To clarify the rationale, we have added a detailed explanation in Section 2.2: wheat flour provides gluten proteins that improve batter viscosity and film formation; sweet potato starch contributes to batter elasticity and colour; kudzu root starch (amylose ~18.2%) forms a dense network with sweet potato starch that improves crust stability and reduces oil uptake; and baking powder generates gas during frying to give a porous, crispy crust. The combination was selected to achieve adequate batter adhesion, a crispy crust, and a tender interior. (Section 2.2, Page 3, Lines 118–123)

 

Comment 6: 6.Section 2.2 describes immersing chicken strips in batter for 10 s and draining for 2–5 s. How was coating pick-up weight controlled and verified across replicates to ensure uniform thickness before frying?

Response 6: We acknowledge that coating pick-up was not quantitatively verified in this experiment. We have explicitly stated this as a limitation in Section 2.2. However, because the same batter batch, dipping time (10 s), and draining time (2–5 s) were applied to all groups, any variation in coating amount would be random rather than systematically associated with temperature. Batter viscosity was also not separately measured for this batch; its flow behaviour was visually checked to be consistent with our previous report [10]. (Section 2.2, Page 3, Lines 126–130; Page 4, Lines 131–132)

[10]Zhang, L., Xiong, S. L.*, Li, A. L., Xiong, D. Q., & Tang, D. (2024). Optimization of Small Crispy Meat Paste Formulation by Response SurfacePrincipal Component Analysis. Science and Technology of Food Industry, 45(4), 133141. https://doi.org/10.13386/j.issn10020306.2023030216

 

Comment 7:What type of tertiary rapeseed oil was used, and how frequently was the frying oil replenished or monitored for total polar compounds to prevent oxidative degradation from confounding results across multi-temperature trials? 

Response 7: We have clarified in Section 2.2 that the frying medium was grade-3 rapeseed oil (GB/T 1536, Daodaoquan Grain and Oil Yueyang Co., Ltd.). Fresh oil was used for each frying batch and discarded after each temperature group; thus, each of the three biological replicates at each temperature was fried in fresh oil. Although the smoke point of grade-3 rapeseed oil is relatively low, the short frying time (170 s) limited oil degradation, and the use of fresh oil for every batch eliminated oil deterioration as a confounding factor across temperature groups. (Section 2.2, Page 3, Lines 121–124)

 

Comment 8: 8.Section 2.5 states that fried strips were minced into powder for fat analysis, and Section 2.6 mentions uniform crushing for E-nose evaluation. Were the crust and core separated for chemical and volatile analyses, or was the whole strip analyzed as a composite?

Response 8: The whole strip (coating + core) was analysed as a composite. We have explicitly stated this in Section 2.5 (Page 4, Line 157) and Section 2.6 (Page 4, Line 171).

 

Comment 9: 9.Table 2 presents instrumental springiness (mm) alongside "sensory springiness (%)". How was "sensory springiness" quantitatively evaluated by the 10-member panel, and why does it follow a different trend than instrumental springiness?

Response 9: We agree that "sensory springiness (%)" lacked a clear methodological definition, could not be reproduced from the Methods, and might confuse readers. We have therefore removed this column from Table 2. The table now reports only instrumental TPA parameters, and the table title has been revised to "Instrumental texture profile parameters…". A footnote clarifies that springiness is expressed as instrumental recovery (mm) measured by TPA. (Table 2, Page 7, Lines 247–254)

 

Comment 10: Section 3.4.2 discusses triethylenediamine-M and D as byproducts of Maillard reactions and notes that blank runs ruled out column contamination. Is triethylenediamine a recognized food volatile or could it be an artifact of plasticizer migration or packaging interaction.

Response 10: We agree with the reviewer that triethylenediamine is not a recognized food volatile. It is primarily known as an industrial catalyst for polyurethane foams and is listed as a potential migrant from food-contact materials. Given the absence of authentic standard confirmation and its known industrial origin, we have removed it from the list of flavor-relevant differential compounds. The text now states that this peak likely represents a migrant rather than a frying-derived flavor compound. It is retained in Table 5 and Figure 8 only for statistical completeness but is explicitly excluded from the flavor interpretation. (Section 3.4.2, Page 10, Lines 350–355; Section 3.4.7, Page 18, Lines 523–527)

 

Comment 11: 11.3-methylbutan-1-ol (isoamyl alcohol) was strongly negatively correlated with sensory scores. Can the authors clarify whether its formation is driven predominantly by leucine degradation in the chicken meat or amino acid reactions in the wheat/starch batter?

Response 11: We acknowledge that the precursor origin (meat vs. batter) cannot be resolved from the present GC-IMS data alone. Both chicken muscle proteins and wheat flour proteins are leucine-rich. We have revised Section 3.4.9 to state this explicitly and have removed any implication that the correlation reflects a causal relationship. We consider a predominantly meat-derived origin more likely, because the negative correlation with sensory scores is more consistent with leucine release from the meat matrix under intense frying conditions than with batter-derived Maillard chemistry. This has been added as a limitation. (Section 3.4.9, Page 21, Lines 570-575)

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript demonstrates that frying temperature (150–190 °C) significantly affects the quality, texture, and volatile profile of batter-breaded chicken breast strips, with the highest sensory scores and oil content obtained at 170 °C for 170 s. Using E-nose, GC–IMS, PCA, OPLS-DA, and OAV analysis, the authors identified key compounds associated with lipid oxidation and Maillard reactions, concluding that frying at 170 °C optimizes the balance between aroma and overall quality.

The originality of the study lies primarily in the integration of E-nose and GC–IMS techniques to evaluate changes in volatile compound profiles as a function of frying temperature.

A general concern is that the samples were fried for 170 s, but their internal temperature was not reported. This omission limits the practical applicability of the findings.

Additional comments:

• Lines 103–105: The words “tertiary” and “gradients” should be deleted.
• Section 2.4: The expression “crispy fried pork” should be corrected. The authors should specify the model of the texture analyzer used and the dimensions of the samples subjected to texture analysis. They should also clarify whether the compression deformation was indeed 100%.
• Line 126: Grinding does not necessarily produce a powder. The authors should specify the particle size or the final physical state of the sample. In addition, the method used to determine oil content should be described, rather than merely identifying the equipment manufacturer.
• Line 131: The notation “M0” should be corrected to “m₀”.
• Line 135: The expression “shell wrapping” should be replaced with “batter coating”.
• Section 2.6: To ensure reproducibility, the authors should specify the dimensions of the samples after grinding and identify the instrument used for grinding.
• Section 2.7: The calculation of the odor activity value (OAV) should be verified, as it is calculated as the ratio of the compound concentration in the sample to its odor threshold, with both expressed on compatible bases and in compatible units. The reference “Nie et al. (2024)” should also be included in the reference list. Furthermore, the amount of sample used for the analysis should be specified.
• Table 2: The terms “Springiness (mm)” and “Sensory springiness (%)” require clarification. Is the unit of measurement for instrumental springiness correct? How were the sensory springiness values determined? Moreover, the authors should explain the relevance of these values, as they are not interpreted in the Results and Discussion section.
• Lines 215–217: The statement that “Excessively high temperatures induce rapid starch gelatinization at the batter surface, forming a compact crust that blocks oil penetration and reduces the final product's oil content” requires appropriate references or experimental evidence. The proposed mechanism should not be presented as established without supporting data.
• Section 3.3: The authors should define the values presented in Figure 3a and clarify whether differences in sensor responses at a given temperature were statistically significant. In Figure 3b, the meaning of the suffixes “-1”, “-2”, and “-3” should be explained. Furthermore, the text states that “The cumulative contribution rate approached 99.5%”, whereas the percentages reported for PC1 and PC2 sum to 98.6% (84.0% + 14.6%). This discrepancy should be corrected.
• In Section 3.4, the statement that “each reaction ion peak (RIP) represents a volatile compound” is incorrect. As indicated in the cited reference, analyte-related signals appear separately from the RIP, which represents the reactant ion signal.
• Lines 249–250: The statement that red indicates a higher concentration and blue a lower concentration should be revised unless the signals have been calibrated for quantitative analysis. GC–IMS signal intensity does not necessarily represent absolute concentration; the authors should refer to relative signal intensity where appropriate.
• The statement that differential spectra show no obvious differences, followed by the claim that fingerprint plots reveal clear differences between groups, requires clarification. The authors should explain the apparent discrepancy between these observations.
• Claims of statistically significant differences require appropriate statistical analysis. Visual inspection of the spectra alone is insufficient to establish significance.
• The authors should clarify whether the 60 volatile compounds were tentatively identified or confirmed using appropriate identification criteria.
• Lines 313–315: The statement that alcohols are mainly derived from microbial metabolism is questionable in the context of a product subjected to high-temperature frying. Lipid oxidation, aldehyde reduction, and thermal degradation may be more relevant pathways, although their relative contributions depend on the compounds concerned.
• Lines 316–318: The explanation that rapid surface-water evaporation prevents nutrient and aroma volatilization is contradictory, since evaporation can promote the release of volatile compounds. The proposed mechanism requires clarification and supporting evidence.
• Line 342: The statement that 2-pentylfuran originates from octanal should be reconsidered. 2-Pentylfuran is commonly associated with the oxidation and thermal degradation of polyunsaturated fatty acids, particularly linoleic acid.
• Lines 349–350: The statement that amino acids in the oil “completely react with starch” is scientifically inaccurate and overstated. The authors should provide a chemically plausible description of the reactions involved in pyrazine formation.
• Lines 450–451: The reported odor threshold of 4 × 10⁻⁶ mg/kg and the resulting OAV values (>10⁹) for (Z)-4-decenal should be carefully verified.

Author Response

Response to Reviewer 2

Summary

We sincerely thank the reviewer for the accurate summary of our study and for recognizing the originality of integrating E-nose and GC–IMS to evaluate volatile compound changes as a function of frying temperature. We also appreciate the general concern regarding the internal temperature of the samples, which we address in detail below.

General concern: A general concern is that the samples were fried for 170 s, but their internal temperature was not reported. This omission limits the practical applicability of the findings.

Response:

We thank the reviewer for raising this important practical point. We acknowledge that the core temperature of the chicken strips was not measured during frying in this study. We agree that reporting core temperature would strengthen the practical applicability of the findings, because it directly determines the degree of protein denaturation and the actual cooking endpoint. This is now explicitly acknowledged as a limitation in the revised manuscript (Section 4, Page 23, Lines 614–616).

However, we would like to clarify why the absence of core-temperature data does not undermine the validity of the temperature-comparison conclusions drawn in this study:

(1) All treatments used identical sample dimensions and frying time. The chicken strips were cut to a uniform size (5 cm × 1 cm × 1 cm) and fried for a fixed duration of 170 s. Because the geometry and time were held constant, the core temperature history was governed primarily by the oil temperature, which was the intended variable.

(2) The sensory, texture, and oil-content results are internally consistent with the expected core-temperature progression. The monotonic increase in instrumental hardness and chewiness with frying temperature (Table 2) is consistent with progressively greater protein denaturation and moisture loss at higher core temperatures. The sensory optimum at 170 °C reflects the point at which the core was adequately cooked while the crust was not over-hardened.

(3) The conclusions are comparative rather than absolute. The study aims to identify the optimal frying temperature among five levels under a fixed time, rather than to prescribe an absolute core-temperature endpoint.

We have added the following statement to the Limitations (Section 4, Conclusions, Page 23, Lines 614–616): "The core temperature of the chicken strips was not measured in this study. Although all samples had identical dimensions and frying time, so that core temperature was governed primarily by the oil temperature, future studies should record core temperature profiles to further support the practical applicability of these findings."

 

Comment 1: Lines 103–105: The words "tertiary" and "gradients" should be deleted.

Response 1: We agree and have deleted them. "Tertiary rapeseed oil" has been replaced with "grade-3 rapeseed oil", which is more accurate and avoids ambiguity in the English context. "Gradients" has been replaced with "levels" because the temperatures are discrete levels rather than a continuous gradient. (Section 2.2, Page 3, Lines 114 and 124)

 

Comment 2: Section 2.4: The expression "crispy fried pork" should be corrected. The authors should specify should specify the model of the texture analyzer used and the dimensions of the samples subjected to texture analysis. They should also clarify whether the compression deformation was indeed 100%.

Response 2: We apologize for the typo. "Crispy fried pork" has been corrected to "crispy fried chicken breast strips". We have also specified the texture analyzer model as TMS-pro (FTC, USA), added the sample dimensions (5 cm × 1 cm × 1 cm), and corrected the compression strain to 70%, which is within the standard range for meat products and avoids probe–plate contact. (Section 2.4, Page 4, Lines 142–149)

 

Comment 3: Line 126: Grinding does not necessarily produce a powder. The authors should specify the particle size or the final physical state of the sample. In addition, the method used to determine oil content should be described, rather than merely identifying the equipment manufacturer.

Response 3: We thank the reviewer for this careful observation. We agree that "powder" was imprecise, because the minced fried strips (containing both muscle and moist batter) form a homogeneous, paste-like matrix rather than a dry powder. We have revised Section 2.5 to state the final physical state explicitly and to note that no sieving was applied and particle size was not measured. Regarding the oil-content method, we have now described the principle rather than only the instrument: oil was determined by solvent extraction with petroleum ether following the Soxhlet principle, using a fully automatic fat analyzer (SOX606, Shandong Haining Scientific Instrument Co., Ltd.). (Section 2.5, Page 4, Lines 155–160)

 

Comment 4: Line 131: The notation "MO" should be corrected to "m."

Response 4: Corrected. The variable is now written as m₀ in the equation and its description. (Section 2.5, Page 4, Line 163)

 

Comment 5: Line 135: The expression "shell wrapping" should be replaced with "batter coating".

Response 5: Replaced. (Section 2.6, Page 4, Line 169)

 

Comment 6: Section 2.6: To ensure reproducibility, the authors should specify the dimensions of the samples after grinding and identify the instrument used for grinding.

Response 6: We have specified that samples were crushed using a meat grinder. The exact particle size after grinding was not separately measured; this has been noted in the revised Methods. (Section 2.6, Page 4, Line 169)

 

Comment 7: Section 2.7: The calculation of the odor activity value (OAV) should be verified, as it is calculated as the ratio of the compound concentration in the sample to its odor threshold, with both expressed on compatible bases and in compatible units. The reference "Nie et al. (2024)" should also be included in the reference list. Furthermore, the amount of sample used for the analysis should be specified.

Response 7: We have revised Section 2.7 to clarify that OAV was calculated as the ratio of semi-quantitative concentration to odor threshold, with both expressed on a compatible basis. Because these concentrations are semi-quantitative rather than absolute, OAVs are now explicitly described as relative indicators of aroma contribution rather than precise absolute values. The sample amount (2.0 g) has been specified, and the reference has been added to the reference list. (Section 2.7, Page 5, Lines 184–190)

 

Comment 8: Table 2: The terms "Springiness (mm)" and "Sensory springiness (%)" require clarification. Is the unit of measurement for instrumental springiness correct? How were the sensory springiness values determined? Moreover, the authors should explain the relevance of these values, as they are not interpreted in the Results and Discussion section.

Response 8: We agree that "Sensory springiness (%)" lacked a clear definition and could not be reproduced. We have removed this column from Table 2. The table now reports only instrumental TPA parameters, and the footnote clarifies that springiness is expressed as instrumental recovery (mm). (Table 2, Page 7, Lines 247–254)

 

Comment 9: Lines 215–217: The statement that "Excessively high temperatures induce rapid starch gelatinization at the batter surface, forming a compact crust that blocks oil penetration and reduces the final product's oil content" requires appropriate references or experimental evidence. The proposed mechanism should not be presented as established without supporting data.

Response 9: We have added appropriate references to support this mechanism. The statement now reads: "Excessively high temperatures induce rapid starch gelatinization at the batter surface, forming a compact crust that blocks oil penetration and reduces the final product's oil content [7,13]." (Section 3.2, Page 7, Lines 270–274)

 

Comment 10: Section 3.3: The authors should define the values presented in Figure 3a and clarify whether differences in sensor responses at a given temperature were statistically significant. In Figure 3b, the meaning of the suffixes "-1", "-2", and "-3" should be explained. Furthermore, the text states that "The cumulative contribution rate approached 99.5%", whereas the percentages reported for PC1 and PC2 sum to 98.6% (84.0% + 14.6%). This discrepancy should be corrected.

Response 10: We have defined the values in Figure 3a as sensor response intensities (instrumental units). One-way ANOVA with Duncan's test (n = 7) was performed, and the results are now reported in the text (S2, S3, S4 significant at P < 0.001; S6 not significant, P = 0.23; S1 and S5 overall significant, P = 0.020 and 0.039). We have explained that the suffixes -1, -2, -3 denote three biological replicates at each temperature. The cumulative contribution has been corrected to 98.6% (PC1 = 84.0%, PC2 = 14.6%), consistent with Figure 3b. (Section 3.3, Page 8, Lines 283–300; Figure 3 caption, Page 8, Lines 308–310)

 

Comment 11: In Section 3.4, the statement that "each reaction ion peak (RIP) represents a volatile compound" is incorrect. As indicated in the cited reference, analyte-related signals appear separately from the RIP, which represents the reactant ion signal.

Response 11: We agree and have corrected this in Section 3.4.1: "The reaction ion peak (RIP) represents the reactant ion signal, and analyte-related signals appear separately from the RIP." (Page 9, Lines 316–318)

 

Comment 12: Lines 249–250: The statement that red indicates a higher concentration and blue a lower concentration should be revised unless the signals have been calibrated for quantitative analysis. GC-IMS signal intensity does not necessarily represent absolute concentration; the authors should refer to relative signal intensity where appropriate.

Response 12: Corrected in Sections 3.4.1 and 3.4.2. Red/blue now explicitly represent relative signal intensity rather than calibrated absolute concentration. (Section 3.4.1, Page 9, Line 322; Section 3.4.2, Page 9, Line 330)

 

Comment 13: The statement that differential spectra show no obvious differences, followed by the claim that fingerprint plots reveal clear differences between groups, requires clarification. The authors should explain the apparent discrepancy between these observations.

Response 13: We have added an explanation in Section 3.4.2: the differential spectra display overall signal patterns at a single comparison level, whereas the Gallery Plot resolves individual compound signals across all samples simultaneously. (Page 9, Lines 332–336)

 

Comment 14: Claims of statistically significant differences require appropriate statistical analysis. Visual inspection of the spectra alone is insufficient to establish significance.

Response 14: We agree. We have systematically revised the discussion so that "significantly" is used only where supported by statistical analysis; otherwise, descriptive terms such as "markedly" or "consistently" are used. Where ANOVA was performed, P values are reported. (Throughout Section 3.4, revised text in red)

 

Comment 15: The authors should clarify whether the 60 volatile compounds were tentatively identified or confirmed using appropriate identification criteria.

Response 15: The 60 compounds were tentatively identified by matching retention indices and drift times against the NIST library and the VOCal GC-IMS database. Compounds without authentic standard confirmation are regarded as putative annotations. This is stated in Sections 2.7 and 3.4.3. (Section 2.7, Page 5, Line 190; Section 3.4.3, Page 11, Line 377)

 

Comment 16: Lines 313–315: The statement that alcohols are mainly derived from microbial metabolism is questionable in the context of a product subjected to high-temperature frying. Lipid oxidation, aldehyde reduction, and thermal degradation may be more relevant pathways, although their relative contributions depend on the compounds concerned.

Response 16: We agree and have completely rewritten the alcohol paragraph in Section 3.4.3. Alcohols are now attributed to three thermally relevant routes: lipid oxidation followed by aldehyde reduction; thermal Strecker degradation of leucine followed by reduction; and thermal retention of high-boiling-point alcohols. The microbial origin has been removed. (Page 14, Lines 398–407)

 

Comment 17: Lines 316–318: The explanation that rapid surface-water evaporation prevents nutrient and aroma volatilization is contradictory, since evaporation can promote the release of volatile compounds. The proposed mechanism requires clarification and supporting evidence.

Response 17: We have revised this explanation. The decrease in overall alcohol content is now attributed to the combined effects of thermal degradation, esterification, and condensation, as well as the formation of a dense crust that retains some volatiles while others are thermally decomposed. (Section 3.4.3, Page 15, Lines 508–512)

 

Comment 18: Line 342: The statement that 2-pentylfuran originates from octanal should be reconsidered. 2-Pentylfuran is commonly associated with the oxidation and thermal degradation of polyunsaturated fatty acids, particularly linoleic acid.

Response 18: Corrected in Section 3.4.3. 2-Pentylfuran is now described as a product of the oxidation and thermal degradation of polyunsaturated fatty acids, particularly linoleic acid. (Page 15, Lines 524–526)

 

Comment 19: Lines 349–350: The statement that amino acids in the oil "completely react with starch" is scientifically inaccurate and overstated. The authors should provide a chemically plausible description of the reactions involved in pyrazine formation.

Response 19: Corrected. The revised text states that amino acids and reducing sugars in the batter and meat undergo Maillard reactions that generate pyrazines, without the overstated "completely react with starch". (Section 3.4.3, Page 15, Lines 530–533)

 

Comment 20: Lines 450–451: The reported odor threshold of 4 × 10⁻⁶ mg/kg and the resulting OAV values (>10⁹) for (Z)-4-decenal should be carefully verified.

Response 20: We have carefully re-examined this issue and confirmed that we could not trace the threshold of (Z)-4-decenal to a reliable primary literature source under our experimental conditions. Since OAV cannot be validly calculated without a verified threshold, we have removed (Z)-4-decenal from the OAV analysis and from Table 6. It is retained only as a VIP-selected compound discussed in terms of its relative abundance. The OAV analysis now identifies three compounds (hexanal-M, butyraldehyde-M, 3-methylbutan-1-ol-M) as both sensorially active and statistically critical. (Section 3.4.8, Page 20, Lines 552–555; Table 6, Page 20–21)

 

Reviewer 3 Report

Comments and Suggestions for Authors

This study investigated the effects of frying temperature (150–190 °C) on the sensory quality, texture, fat content and volatile compound profile of breaded chicken breast strips, using modern analytical techniques (E-nose, GC-IMS) and multivariate biostatistical methods (PCA, OPLS-DA, VIP, OAV). This study is a contemporary piece of research of high industrial value that examines the impact of frying temperature on product quality parameters.

The subject of this research is of considerable value to food science and industry. However, some sections of the article require revision. Revising the points outlined below will enhance the article’s suitability for publication.

 

Abstract

 

Lines 15–22: Specify clearly in the Abstract whether the 49.8% oil content is calculated on a dry basis or a wet basis.

 

Materials and Methods

 

Lines 93–96: Specify chicken breed, slaughter age, and post-mortem ageing period before freezing/thawing. Running water thawing for 2 h may impact drip loss and water-holding capacity.

Lines 98–103: Report batter viscosity, batter temperature, and coating pick up percentage (%) for the starch-flour batter mixture.

Line 118: Replace “crispy fried pork” with “crispy fried chicken breast strips”.

Lines 121–122: Compression strain is listed as 100%. Squeezing samples to 100% strain destroys sample integrity and measures probe-plate impact. Standard TPA strain should be 30%–70%.

Lines 149–150: Incubation was performed at 60 °C for 15 min. Discuss whether 60 °C incubation causes thermal degradation or artefacts during headspace sampling.

 

Results and Discussion

 

Lines 208–213: Audit the 49.8% value. Compare oil absorption trends with established literature on battered poultry products.

Lines 267–275: Validate the presence of Triethylenediamine using an authentic reference standard, or acknowledge the limitations of library matching.

Lines 311–312: Check subscript formatting, standard deviation expressions, and chemical compound nomenclature in Table 3.

Lines 450–453: Remove the claims of “>10^9” in the text to match Table 6 (10^5 magnitude) and describe concentration quantification transparently.

Lines 459–473: Pearson correlation across 5 treatment groups (n=5) has low statistical power. Indicate exact P-values and confidence intervals in the text.

 

References

 

Lines 515–635: Standardise journal title abbreviations (e.g., “Nature Communications”; “Food Chemistry”; “Food Research International”; “Comprehensive Reviews in Food Science and Food Safety”) and correct typographical errors across reference citations.

Author Response

Response to Reviewer 3

Summary

We sincerely thank the reviewer for the positive evaluation and constructive suggestions. We have carefully revised the manuscript accordingly, and all changes are marked in red in the resubmitted files.

 

Point-by-point response to Comments and Suggestions for Authors

Comment 1: Lines 15–22: Specify clearly in the Abstract whether the 49.8% oil content is calculated on a dry basis or a wet basis.

Response 1: We have clarified in the Abstract that the 49.8% value is total fat content on a wet basis for the whole product (coating + core). The same definition has been added to Section 2.5 for consistency. (Abstract, Page 1, Line 21; Section 2.5, Page 4, Line 153)

 

Comment 2: Lines 93–96: Specify chicken breed, slaughter age, and post-mortem ageing period before freezing/thawing. Running water thawing for 2 h may impact drip loss and water-holding capacity.

Response 2: We have added to Section 2.1: the raw material was commercial White Feather broiler breast; birds were slaughtered at 35–42 d of age; carcasses were chilled at 0–4 °C for post-mortem ageing, trimmed and portioned, then blast-frozen and stored at −18 °C. We acknowledge that thawing method can affect drip loss; however, all groups used the same batch of raw material and identical thawing protocol, so any thawing-related variation would be consistent across groups and would not confound the temperature comparison. (Section 2.1, Page 3, Lines 96–105)

 

Comment 3: Lines 98–103: Report batter viscosity, batter temperature, and coating pick up percentage (%) for the starch-flour batter mixture.

Response 3: Batter temperature is now reported (equilibrated to 20–25 °C before dipping). Batter viscosity was not separately measured for this batch, and coating pick-up was not quantitatively verified; this is acknowledged as a limitation in Section 2.2. Because the same batter batch and identical dipping/draining procedures were applied to all groups, any variation would be random rather than systematically associated with temperature. (Section 2.2, Page 3, Lines 126–130; Page 4, Lines 131–132)

 

Comment 4: Line 118: Replace "crispy fried pork" with "crispy fried chicken breast strips".

Response 4: Corrected in Section 2.4. (Page 4, Line 142)

 

Comment 5: Lines 121–122: Compression strain is listed as 100%. Squeezing samples to 100% strain destroys sample integrity and measures probe-plate impact. Standard TPA strain should be 30%–70%.

Response 5: We have corrected the compression strain to 70%, which is within the standard range for meat products and avoids probe–plate contact. (Section 2.4, Page 4, Line 145)

 

Comment 6: Lines 149–150: Incubation was performed at 60 °C for 15 min. Discuss whether 60 °C incubation causes thermal degradation or artefacts during headspace sampling.

Response 6: We have added a statement in Section 2.7 acknowledging that incubation at 60 °C for 15 min is a standard GC-IMS headspace condition; while some thermally labile compounds may undergo minor changes, the same condition was applied to all samples, so comparisons among temperatures remain valid. (Section 2.7, Page 5, Lines 178–180)

 

Comment 7: Lines 208–213: Audit the 49.8% value. Compare oil absorption trends with established literature on battered poultry products.

Response 7: We have clarified in Section 2.5 that the value represents total fat on a wet basis for the whole product, including the coating and core. In Section 3.2, we now explain that this value is higher than literature values (approximately 18%–25%) primarily because it includes the coating and is expressed on a wet basis, whereas many literature values refer to the core only or a dry basis. The temperature-dependent trend (peak at 170 °C) is internally consistent and independent of the absolute value. (Section 2.5, Page 4, Lines 153–156; Section 3.2, Page 7, Lines 262–266)

 

Comment 8: Lines 267–275: Validate the presence of Triethylenediamine using an authentic reference standard, or acknowledge the limitations of library matching.

Response 8: We acknowledge that we did not validate triethylenediamine with an authentic standard. Given its known industrial origin as a potential food-contact migrant and the absence of standard confirmation, we have excluded it from the flavor interpretation. It is retained in Table 5 and Figure 8 for data completeness but is not discussed as a frying-derived flavor compound. (Section 3.4.2, Page 10, Lines 350–355; Section 3.4.7, Page 18, Lines 523–527)

 

Comment 9: Lines 311–312: Check subscript formatting, standard deviation expressions, and chemical compound nomenclature in Table 3.

Response 9: We have carefully corrected subscript formatting, unified standard deviation expressions, and standardized chemical compound nomenclature throughout Table 3. (Table 3, Page 12–14)

 

Comment 10: Lines 450–453: Remove the claims of >10⁹ in the text to match Table 6 (10⁵ magnitude) and describe concentration quantification transparently.

Response 10: We have removed the ">10⁹" claim. The text now states that hexanal-M and butyraldehyde-M exhibited the highest OAVs (>10⁵), followed by 3-methylbutan-1-ol-M (34–49). (Z)-4-decenal was excluded from the OAV analysis because its threshold could not be verified. Section 2.7 now describes the concentration quantification transparently, and all OAVs are described as semi-quantitative relative indicators. (Section 3.4.8, Page 20, Lines 552–555; Section 2.7, Page 5, Lines 184–190)

 

Comment 11: Lines 459–473: Pearson correlation across 5 treatment groups (n=5) has low statistical power. Indicate exact P-values and confidence intervals in the text.

Response 11: We have recalculated the correlation analysis using all 15 samples (n = 15), which substantially improves statistical power. Exact r and P values are now reported in Section 3.4.9. For example: 3-methylbutan-1-ol vs. sensory score (r = −0.742, P = 0.0015); cinnamyl alcohol vs. sensory score (r = 0.784, P = 0.0006); 2-methylpyrazine vs. sensory score (r = 0.799, P = 0.0004). The figure caption has been updated accordingly. (Section 3.4.9, Page 21, Lines 568–574; Figure 9 caption, Page 22)

 

Comment 12: Lines 515–635: Standardise journal title abbreviations (e.g., "Nature Communications"; "Food Chemistry"; "Food Research International"; "Comprehensive Reviews in Food Science and Food Safety") and correct typographical errors across reference citations.

Response 12: We have standardized journal title abbreviations and corrected typographical errors throughout the reference list. (References, Page 25–30)

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Comments have been addressed. Paper can be accepted. 

Reviewer 3 Report

Comments and Suggestions for Authors

The authors' thorough revisions, conducted in accordance with the reviewers' suggestions, are praiseworthy. Significant revisions have been made throughout the article, including the title and references. The revisions I proposed in the previous version have been implemented precisely. There is a notable distinction between the preliminary and final versions of the article. The article has significantly improved. Consequently, I have no additional recommendations for the final revised version of the article.