Acid Hydrothermal Amendment of Grape Wine Pomace: Enhancement of Phenol and Carbohydrate Co-Solubilization
Round 1
Reviewer 1 Report
Authors present the assessment of bioactive compounds and carbohydrates solubilization from grape pomace submitted to hydrothermal treatment. The manuscript is appropriately written, and it contains relevant contributions to Agronomy Research. However, my recommendation is to accept publication after the following revisions:
It would be interesting to present the equations of the fitted models used to create the response surfaces (together with the adjusted R squared and the residual standard error). Based on these equations, it could be estimated the conditions of maximum total soluble phenols, antioxidant capacity and carbohydrate solubilization. If it is possible, it would be interesting to validate these optimum conditions with experimental data.
It would be interesting to add error bars in Figure 6. Was it applied a comparative test, like Tukey test, between the averages of data from figures 1, 3, 4 and 6? If the answer is yes, it could be added letters to identify what averages are different with 5% of significance. Was the analysis of variance from table S1 conducted with data from figure 4? This analysis could also be carried out with data from figures 1, 3 and 6. It would also be interesting to add if analyses of variance assumptions were guaranteed (homogeneity of variance, independent residuals and normal distribution of residuals).
It would also be interesting to add the results of total soluble phenols that were used to generate the response surfaces.
Typo should be revised. For example, “pirinola filters. total sugars… ” (Line 121).
Author Response
REVIEWER #1:
Authors present the assessment of bioactive compounds and carbohydrates solubilization from grape pomace submitted to hydrothermal treatment. The manuscript is appropriately written, and it contains relevant contributions to Agronomy Research. However, my recommendation is to accept publication after the following revisions:
Reviewer #1 comment 1: It would be interesting to present the equations of the fitted models used to create the response surfaces (together with the adjusted R squared and the residual standard error). Based on these equations, it could be estimated the conditions of maximum total soluble phenols, antioxidant capacity and carbohydrate solubilization. If it is possible, it would be interesting to validate these optimum conditions with experimental data.
Authors’ response: The authors incorporate the equations of the fitted models used to create the response surface graphics in the manuscript as follows: “The model relating the total soluble phenols to the experimental factors was obtained from Eq. 1, where A, B, and C were time, sulfuric acid, and temperature, respectively (see supplementary material, Table S1): (Eq 1)” (Lines 272-276), and “The model relating the carbohydrates solubilization to the experimental factors was obtained from Eq. 2, where A, B, and C were time, sulfuric acid, and temperature, respectively (see supplementary material, Table S1): (Eq 2)” (Lines 444-449). Details about the fitting quality of the model have been also included in the table S1, in supplementary material.
Reviewer #1 comment 2: It would be interesting to add error bars in Figure 6.
Authors’ response: The authors have added error bars in Figure 6 in accordance with the reviewer´s suggestion (see Figure 6).
Reviewer #1 comment 3: Was it applied a comparative test, like Tukey test, between the averages of data from figures 1, 3, 4 and 6? If the answer is yes, it could be added letters to identify what averages are different with 5% of significance. Was the analysis of variance from table S1 conducted with data from figure 4? This analysis could also be carried out with data from figures 1, 3 and 6. It would also be interesting to add if analyses of variance assumptions were guaranteed (homogeneity of variance, independent residuals and normal distribution of residuals).
Authors’ response: the authors have performed ANOVA to determine statistical difference between the averages of data from figures 1, 3 and 6. The description of the statistical analysis was included in the materials & methods section in the following form: “ANOVA was performed for each response. In all cases, model significance and lack-of-fit tests were performed to check that the models used were relevant and fitted the experimental data. All statistical analyses were performed considering α = 0.05 (Supplementary material, Table S1 and S2).” (Lines 121-124). The results have been included in form of tables in the supplementary material (Tables S1 and S2). The results of the ANOVA tests have been also implemented in the discussion of the results to show significative or not significative differences among the tested conditions: “This highest concentration was similar to that obtained in treatments 4, 7 and 12, with no significant differences between the three values (Supplementary material, Table S2).” (Lines 247-249), “This highest antioxidant power did not show any statistical difference from those obtained for treatments 7, 8, 12 and 14 (Supplementary material, Table S2), whose values were 18±1 g eq. Trolox/kg of GP, 18±2 1 g eq. Trolox/kg of GP, 189±1 1 g eq. Trolox/kg of GP and 18±2 1 g eq. Trolox/kg of GP, respectively.” (Lines 304-308) and “The analysis of variance shows that there are no statistical differences between treatments 4, 7, 8 and 12, but that there are between 4 and 3 (Supplementary material, Table S2)” (Lines 391-393).
Reviewer #1 comment 4: It would also be interesting to add the results of total soluble phenols that were used to generate the response surfaces.
Authors’ response: The response surface graphics for the total soluble phenols were shown in Figure 1.
Reviewer #1 comment 5: Typo should be revised. For example, “pirinola filters. total sugars… ” (Line 121).
Authors’ response: The authors apologize for the mistake. The entire manuscript has been carefully revised to correct all the typos.
Reviewer 2 Report
Page 2 line 53 – “GP can content a polyphenol concentration between 1 and 5% in dry matter”
This range of concentrations depends on polyphenol standard equivalent, or extraction method etc and the references cited in the text are not in accordance with the sentence content. Please rephrase and remove the declared range or provide details.
Page 2 lines 89-90 – There is no need to provide data in the aim of the paper section.
Page 3 lines 129 – The reference cited in the text does not present standard methods for TS, VS and sCOD. Please describe the methods used or cite a valid paper
Page 3 lines 130 – OMSW – describe the term
Page 4 lines 136 – The reference numbered 29 does not describe an HPLC determination method for acetic acid, furfurol and HMF etc. Detail about method must be declared.
Page 4 lines 149 – Romero Roman is the 37th reference on bibliography section. Please verify the numerotation
Page 6 fig 1 line 223 – “The highest increase was observed for hydrothermal treatment 4”. How do you know if it is the highest? In the figure is not declared the significance of differences. What about the treatment 4 and 7 for example? They are statistically different?
Same observation for figure 3
The abstract must be corrected in accordance with results section. Without a study of difference of significance between treatments you cannot declare which one is the the most powerful.
Minor English editing is needed, especially in the introduction section
Author Response
REVIEWER #2:
Reviewer #2 comment 1: Page 2 line 53 – “GP can content a polyphenol concentration between 1 and 5% in dry matter”. This range of concentrations depends on polyphenol standard equivalent, or extraction method etc. and the references cited in the text are not in accordance with the sentence content. Please rephrase and remove the declared range or provide details.
Authors’ response: the incorrect information has been removed from the manuscript. As alternative, the authors have provided details about the distribution of the polyphenols in the grape structure in the following form: “GP can contain a considerable concentration of polyphenols, since most of the polyphenols in the grape are usually found in the seeds (60-70%) and skin (28-35%), whereas the pulp has a lower percentage content (10%)” (Lines 55-58).
Reviewer #2 comment 2: Page 2 lines 89-90 – There is no need to provide data in the aim of the paper section.
Authors’ response: These lines were deleted in accordance with the reviewer´s suggestion.
Reviewer #2 comment 3: Page 3 lines 129 – The reference cited in the text does not present standard methods for TS, VS and sCOD. Please describe the methods used or cite a valid paper.
Authors’ response: the authors apologize for the confusion. The correct reference has been included in the manuscript: “American Public Health, A., Eaton, A.D., American Water Works, A. and Water Environment, F. (2005) Standard methods for the examination of water and wastewater, APHA-AWWA-WEF, Washington, D.C.”.
Reviewer #2 comment 4: Page 3 lines 130 – OMSW – describe the term.
Authors’ response: The term OMSW has been deleted from the manuscript.
Reviewer #2 comment 5: Page 4 lines 136 – The reference numbered 29 does not describe an HPLC determination method for acetic acid, furfurol and HMF etc. Detail about method must be declared.
Authors’ response: The correct reference has been included in the manuscript: Rocha, S., Marzialetti, T., Kopp, M., Cea, M., 2021. Reaction Mechanism of the Microwave-Assisted Synthesis of 5-Hydroxymethylfurfural from Sucrose in Sugar Beet Molasses. catalysts 11, 1–11.
Reviewer #2 comment 6: Page 4 lines 149 – Romero Roman is the 37th reference on bibliography section. Please verify the numerotation
Authors’ response: The authors apologize for the confusion. The correct reference has been included in the manuscript: Romero-Román, M.E., Schoebitz, M., Fuentealba, J., García-Viguera, C., López Belchí, M.D., Voilley, A., Kurek, M., 2021. Phenolic Compounds in Calafate Berries Encapsulated by Spray Drying: Neuroprotection Potential into the Ingredient.
Reviewer #2 comment 7: Page 6 fig 1 line 223 – “The highest increase was observed for hydrothermal treatment 4”. How do you know if it is the highest? In the figure is not declared the significance of differences. What about the treatment 4 and 7 for example? They are statistically different? Same observation for figure 3.
Authors’ response: the authors have performed ANOVA to determine statistical difference between the averages of data from figures 1, 3 and 6. The description of the statistical analysis was included in the materials & methods section in the following form: “ANOVA was performed for each response. In all cases, model significance and lack-of-fit tests were performed to check that the models used were relevant and fitted the experimental data. All statistical analyses were performed considering α = 0.05 (Supplementary material, Table S1 and S2).” (Lines 121-124). The results have been included in form of tables in the supplementary material (Tables S1 and S2). The results of the ANOVA tests have been also implemented in the discussion of the results to show significative or not significative differences among the tested conditions: “This highest concentration was similar to that obtained in treatments 4, 7 and 12, with no significant differences between the three values (Supplementary material, Table S2).” (Lines 247-249), “This highest antioxidant power did not show any statistical difference from those obtained for treatments 7, 8, 12 and 14 (Supplementary material, Table S2), whose values were 18±1 g eq. Trolox/kg of GP, 18±2 1 g eq. Trolox/kg of GP, 189±1 1 g eq. Trolox/kg of GP and 18±2 1 g eq. Trolox/kg of GP, respectively.” (Lines 304-308) and “The analysis of variance shows that there are no statistical differences between treatments 4, 7, 8 and 12, but that there are between 4 and 3 (Supplementary material, Table S2)” (Lines 391-393).
Reviewer #2 comment 8: The abstract must be corrected in accordance with results section. Without a study of difference of significance between treatments you cannot declare which one is the the most pow
Authors’ response: The information provided by the abstract has been revised after carrying out the statistical analysis above mentioned.
Reviewer 3 Report
The study carried out low-temperature hydrothermal treatments of white grape pomace using different operational conditions for biorefinery processes.
The manuscript has some novelties and can be published after some revisions. My main concerns are related to:
1) English needs revision.
2) A detailed subsection about the statistical analysis should be included.
3) Detailed conditions for GC analysis should be considered.
4) Almost no details about the protocols used to measure lignin and holocellulose.
English needs revision.
Author Response
REVIEWER #3
Reviewer #3 comment 1:
The study carried out low-temperature hydrothermal treatments of white grape pomace using different operational conditions for biorefinery processes. The manuscript has some novelties and can be published after some revisions. My main concerns are related to:
Reviewer #3 comment 1: English needs revision.
Authors’ response: The whole document has been revised by an expert native speaker. All the changes have been highlighted throughout the manuscript.
Reviewer #3 comment 2: A detailed subsection about the statistical analysis should be included.
Authors’ response: the authors have performed ANOVA to determine statistical difference between the averages of data from figures 1, 3 and 6. The description of the statistical analysis was included in the materials & methods section in the following form: ANOVA was performed for each response. In all cases, model significance and lack-of-fit tests were performed to check that the models used were relevant and fitted the experimental data. All statistical analyses were performed considering α = 0.05 (Supplementary material, Table S1 and S2).” (Lines 121-124).
Reviewer #3 comment 3: Detailed conditions for GC analysis should be considered.
Authors’ response: More details and updated references have been included for all the different equipment and methodologies used in the experimentation (see section 2.3 Chemical analysis).
Reviewer #3 comment 4: Almost no details about the protocols used to measure lignin and holocellulose.
Authors’ response: The authors have corrected the reference about the protocols used to measure lignin and holocellulose.
Reviewer 4 Report
Manuscript entitled “Acid hydrothermal amendment of grape wine pomace: enhancement of phenol and carbohydrate co-solubilization” is valuable, well planned and well documented experiment.
Minor corrections: punctuation eg.H2SO4
Table 4: the measurement uncertainty should be given to the number of decimal places in the result
Author Response
REVIEWER #4
Manuscript entitled “Acid hydrothermal amendment of grape wine pomace: enhancement of phenol and carbohydrate co-solubilization” is valuable, well planned and well documented experiment.
Reviewer #4 comment 1: Minor corrections: punctuation eg.H2SO4
Authors’ response: The authors apologize for the mistake. The entire manuscript has been carefully revised to correct all the typos.
Reviewer #4 comment 2: Table 4: the measurement uncertainty should be given to the number of decimal places in the result.
Authors’ response: the authors have corrected the number of decimals presented in Table 4 according to the reviewer´s comment.
