Study of Wine Volatile Composition of Tempranillo versus Tempranillo Blanco, a New White Grape Variety
, Pilar Rubio-Bretón, Sandra Marín-San Román, Elisa Baroja, Itziar Sáenz de Urturi and Eva P. Pérez-Álvarez *Round 1
Reviewer 1 Report
General evaluation
This study by Teresa Garde-Cerdán and collaborators compares the final aroma spectra in two closely related wine varieties. The work is well conceived and impeccably conducted and presented. The results obtained are definitely of some interest to producers and consumers of these wines.
Minor comments:
The axis labels of Figures 4 - 6 are of microscopic size. I recommend the use of colors as in the figures before.
Line 222: allow
Line 228: make
Line 308: Oenococcus oeni in italics
Author Response
MANUSCRIPT ID Beverages-1426890
RESPONSE TO REVIEWER 1 AND CHANGES WE HAVE MADE TO THE MANUSCRIPT
Firstly, please accept our thanks for the comments you have made on our paper. Your suggestions have helped to improve the quality of the paper. We hope that the answers outlined below and the changes we have made to the text will be satisfactory.
General evaluation
This study by Teresa Garde-Cerdán and collaborators compares the final aroma spectra in two closely related wine varieties. The work is well conceived and impeccably conducted and presented. The results obtained are definitely of some interest to producers and consumers of these wines.
Minor comments:
The axis labels of Figures 4 - 6 are of microscopic size. I recommend the use of colors as in the figures before.
Answer: According to your suggestion, we have increased the font size of the x-axis in the Figures 4-6 and used colors as in the Figures 1-3.
Line 222: allow
Answer: We have changed “allows” by “allow” (line 276).
Line 228: make
Answer: We have changed “made” by “make” (line 282).
Line 308: Oenococcus oeni in italics
Answer: We have written Oenococcus oeni in italics (line 392).
Reviewer 2 Report
The manuscript is interesting and presents a subject of great interest to oenology and which concerns the deepening of knowledge about a new variety.
However, there are some issues that must be clarified to improve the quality of the article.
The major issues are:
1-Result analysis and experimental design: considering that wines from both varieties are analyzed for 3 years, and several studies have demonstrated the effect of the year on the volatile composition of wines, it is not understood why the ANOVA was not carried out considering the two factors (variety and year).
2- Bearing in mind that a semi-quantitative method was used to analise volatiles (line 81-82), the results obtained are expressed in mg of internal standard, assuming a response factor equal to 1 for all compounds. Thus, in the legends of Figures 1, 2, 3 4, 5 and 6 the form of expression of the concentration must be corrected. On the other hand and taking into account that the quantification is relative, some care must be taken when comparing the detection threshold values (example line 140..)
3 – According the material and methods the wine samples were frozen at -20ºC until being analyzed. Doesn't this procedure influence the volatile content? How is the thawing procedure to carry out the analyses afterwards?
4 - Wine technology: bearing in mind that the authors are comparing a white and a red variety, the procedure for obtaining white wine must be different from that of red wine. Details of the two procedures should be given: on the white juice was clarification carried out before fermentation? how? in red juice, how much time for maceration of the solid parts? Were fermentation temperatures the same for both varieties? Amount of yeast and lactic acid inoculum applied?
Minor issues:
1- Method of analysis of volatile compounds in wines: the authors follow the method described by Rubio Breton et al [14], which refers to a method described by Moreno et al. [2017] and Oliveira et al 2006. I suggest that the authors cite those people who proposed the method, indicating the modifications introduced. The authors cited in the manuscript use 4-nonanol as an internal standard and the authors of this manuscript use 2-octanol. It is noteworthy that authors should indicate the concentration of the internal standard used.
2- Before discussing the volatile results, some basic characteristics of the wines should be provided (alcoholic content, acidity and residual sugars). On the other hand, taking into account that the volatiles presented are of fermentative origin, some information about the fermentation process of the samples should also be provided.
Author Response
MANUSCRIPT ID Beverages-1426890
RESPONSE TO REVIEWER 2 AND CHANGES WE HAVE MADE TO THE MANUSCRIPT
Firstly, we would like to thank the reviewer for his/her useful comments and appreciation of our paper. A point-by-point response to the comments is provided below and the corresponding parts of the manuscript were modified accordingly.
The manuscript is interesting and presents a subject of great interest to oenology and which concerns the deepening of knowledge about a new variety.
However, there are some issues that must be clarified to improve the quality of the article.
The major issues are:
1-Result analysis and experimental design: considering that wines from both varieties are analyzed for 3 years, and several studies have demonstrated the effect of the year on the volatile composition of wines, it is not understood why the ANOVA was not carried out considering the two factors (variety and year).
Answer: We agree with the reviewer that one of the determining factors in grape and wine composition is the season. However, the main objective of the study was to evaluate the volatile composition of wines made with Tempranillo and Tempranillo Blanco grape varieties in order to compare the aromatic composition between these two varieties, the latter originating from spontaneous mutation of the first one. It was considered to cover 3 seasons so that the study would be more robust, and the conclusions more global, regardless of the season, and therefore, the statistical study was made considering all the wines made in the three vintages.
2- Bearing in mind that a semi-quantitative method was used to analise volatiles (line 81-82), the results obtained are expressed in mg of internal standard, assuming a response factor equal to 1 for all compounds. Thus, in the legends of Figures 1, 2, 3 4, 5 and 6 the form of expression of the concentration must be corrected. On the other hand and taking into account that the quantification is relative, some care must be taken when comparing the detection threshold values (example line 140..)
Answer: Thank you for your suggestion. We have changed the form of expression of the volatile compounds concentration in the legends of the 6 figures, we believe it is now more correct. Throughout the manuscript, we have tried to be more careful when comparing the concentrations of the analytes that we have quantified in the wines with the detection threshold values found in the literature.
3 – According the material and methods the wine samples were frozen at -20ºC until being analyzed. Doesn't this procedure influence the volatile content? How is the thawing procedure to carry out the analyses afterwards?
Answer: The wine samples were frozen in order to stop the possible evolution of the analytes of interest and thus be able to determine their composition at a specific time. As for the defrosting process, the day before analysis, the wines (stored in a Falcon) were removed from the freezer and placed in the refrigerator, at a low and controlled temperature, and once defrosted, they were immediately processed in order to study their volatile composition, according to the method described in the manuscript, in a laboratory where the temperature was also controlled.
4 - Wine technology: bearing in mind that the authors are comparing a white and a red variety, the procedure for obtaining white wine must be different from that of red wine. Details of the two procedures should be given: on the white juice was clarification carried out before fermentation? how? in red juice, how much time for maceration of the solid parts? Were fermentation temperatures the same for both varieties? Amount of yeast and lactic acid inoculum applied?
Answer: We appreciate the reviewer's comment. We have added detailed information about the winemaking processes for both varieties (section 2.1 of Materials and Methods).
Minor issues:
1- Method of analysis of volatile compounds in wines: the authors follow the method described by Rubio Breton et al [14], which refers to a method described by Moreno et al. [2017] and Oliveira et al 2006. I suggest that the authors cite those people who proposed the method, indicating the modifications introduced. The authors cited in the manuscript use 4-nonanol as an internal standard and the authors of this manuscript use 2-octanol. It is noteworthy that authors should indicate the concentration of the internal standard used.
Answer: In agreement with your suggestion, we have cited the people who proposed the method. Initially, our research group applied this method using 4-nonanol as internal standard, but in some wines with high volatile acidity, this standard eluted together with acetic acid, so we decided to replace it with 2-octanol, an internal standard widely used in the determination of the volatile composition of wines. The concentration of 2-octanol used has been added, according to your suggestion (lines 97-98).
2- Before discussing the volatile results, some basic characteristics of the wines should be provided (alcoholic content, acidity and residual sugars). On the other hand, taking into account that the volatiles presented are of fermentative origin, some information about the fermentation process of the samples should also be provided.
Answer: According to your suggestion, the results of the determination of basic characteristics of the wines (lines 121-123), as well as the methods used and the reference, have been added (lines 80-81 and 372). As mentioned above, we have added detailed information on the winemaking processes for both varieties (section 2.1 of Materials and Methods).
Reviewer 3 Report
The manuscript entitled "Study of volatile wine composition of Tempranillo versus Tempranillo Blanco, a new white grape variety" addresses a topical issue. Volatile compounds are among the most popular components in wine. It is a well-structured work and I am easy to follow. However, for the manuscript to be published, I would have a few recommendations:
In the abstract I recommend adding the purpose of this studio.
The introduction can be improved with some information from the literature on studies on volatile compounds in wine.
If you want to give details about the history of Tempranillo Blanco in the introduction, I also recommend detailing Tempranillo.
2. Materials and Methods
2.1. Tempranillo and Tempranillo Blanco wine samples
I recommend the description of Tempranillo and Tempranillo Blanco varieties.
The technological process is very succinctly presented, it is not reproducible. I recommend the detailed description or a detailed technological scheme.
3. Results and Discussion
Given that this manuscript focuses on volatile compounds, essential data such as retentive time and characteristic odor descriptors for each component are missing. There is also a lack of discussions related to existing studies in the literature.
Author Response
MANUSCRIPT ID Beverages-1426890
RESPONSE TO REVIEWER 3 AND CHANGES WE HAVE MADE TO THE MANUSCRIPT
Firstly, we want to thank you for your comments as well as your revision of the manuscript. Below we have made a detailed reply to each of your observations. We have also corrected the manuscript in accordance with your suggestions.
The manuscript entitled "Study of volatile wine composition of Tempranillo versus Tempranillo Blanco, a new white grape variety" addresses a topical issue. Volatile compounds are among the most popular components in wine. It is a well-structured work and I am easy to follow. However, for the manuscript to be published, I would have a few recommendations:
In the abstract I recommend adding the purpose of this studio.
Answer: According to your suggestion, we have added the purpose of this work in the Abstract.
The introduction can be improved with some information from the literature on studies on volatile compounds in wine.
Answer: In accordance with your comment, we have tried to improve the Introduction section by citing works whose topic is the same as that of the present manuscript. (Lines 36-40).
If you want to give details about the history of Tempranillo Blanco in the introduction, I also recommend detailing Tempranillo.
Answer: According to your recommendation, we have added information about the recently known history of the Tempranillo variety. (Lines 41-43).
2. Materials and Methods
2.1. Tempranillo and Tempranillo Blanco wine samples
I recommend the description of Tempranillo and Tempranillo Blanco varieties. The technological process is very succinctly presented, it is not reproducible. I recommend the detailed description or a detailed technological scheme.
Answer: We appreciate the reviewer's comment. We have added detailed information on the winemaking processes of both varieties (section 2.1 of Materials and Methods).
3. Results and Discussion
Given that this manuscript focuses on volatile compounds, essential data such as retentive time and characteristic odor descriptors for each component are missing. There is also a lack of discussions related to existing studies in the literature.
Answer: Thank you for your comments. We believe that information such as retentive time or characteristic odor descriptors for each compounds are not relevant in this work, since it is neither focused on the development of an analytical method nor on a study of the thresholds of perception of volatile compounds by GC-O. However, if the reviewer and/or editor considers it necessary, we can add a table with such information.
We have tried to improve the discussion of the results related to existing studies in literature on the topic of this manuscript.
Round 2
Reviewer 2 Report
The authors answered the questions asked and made corresponding changes.
However, there were some minor issues that should be corrected:
Line 88 - the harvest years must be indicated
Line 62- instead of just one value (which I deduce will be the average value of the 3 years) I suggest the range of values or the average value with the associated standard deviation.
Line 86 - the freezing and thawing process that was explained in the answer by the authors should be included in the manuscript as a previous sample preparation procedure.
Line 98 - The 2-octanol is prepared in aqueous solution? It is just to check as this standard is usually prepared in hydroalcoholic solution.
Line 121 - 126 - instead of just one value for the alcohol content and for the acidity (which I assume will be the average value over the 3 years) I suggest the range of values or the average value with the associated standard deviation.
However, a bigger issue came up with the publication of your team:
Garde-Cerdán, T., da Costa, N.L., Rubio-Bretón, P. et al. The Most Important Parameters to Differentiate Tempranillo and Tempranillo Blanco Grapes and Wines through Machine Learning. Anal Food. Methods 14, 2221-2236 (2021). https://0-doi-org.brum.beds.ac.uk/10.1007/s12161-021-02049-6
This publication presents volatile results from vintages for the same varieties. It seems to me that there is an overlap with the results presented here. I think that this work should be referred to in the introduction and that the authors should explain well the difference between the two works.
Author Response
MANUSCRIPT ID Beverages-1426890
RESPONSE TO REVIEWER 2 AND CHANGES WE HAVE MADE TO THE MANUSCRIPT
Firstly, we want to thank you for your comments as well as your revision of the manuscript. Below we have made a detailed reply to each of your observations. We have also corrected the manuscript in accordance with your suggestions.
The authors answered the questions asked and made corresponding changes.
However, there were some minor issues that should be corrected:
Line 88 - the harvest years must be indicated
Answer: According to your suggestion, we have indicated the harvest years (line 86).
Line 62- instead of just one value (which I deduce will be the average value of the 3 years) I suggest the range of values or the average value with the associated standard deviation.
Answer: In accordance with your comment, we have added the associated standard deviation (lines 65-66 and line 67).
Line 86 - the freezing and thawing process that was explained in the answer by the authors should be included in the manuscript as a previous sample preparation procedure.
Answer: According to your recommendation, we have added this information in the manuscript (lines 91-94).
Line 98 - The 2-octanol is prepared in aqueous solution? It is just to check as this standard is usually prepared in hydroalcoholic solution.
Answer: We appreciate the reviewer's comment. The 2-octanol was prepared in ethanol (line 98).
Line 121 - 126 - instead of just one value for the alcohol content and for the acidity (which I assume will be the average value over the 3 years) I suggest the range of values or the average value with the associated standard deviation.
Answer: In accordance with your comment, we have added the associated standard deviation (lines 21-23).
However, a bigger issue came up with the publication of your team:
Garde-Cerdán, T., da Costa, N.L., Rubio-Bretón, P. et al. The Most Important Parameters to Differentiate Tempranillo and Tempranillo Blanco Grapes and Wines through Machine Learning. Anal Food. Methods 14, 2221-2236 (2021). https://0-doi-org.brum.beds.ac.uk/10.1007/s12161-021-02049-6
This publication presents volatile results from vintages for the same varieties. It seems to me that there is an overlap with the results presented here. I think that this work should be referred to in the introduction and that the authors should explain well the difference between the two works.
Answer: Thank you for your comment. Certainly, in this study, the volatile composition is used, together with the nitrogen and phenolic composition, in order to discriminate the grapes and wines of both varieties, using statistical tools. However, a detailed study of the fermentative volatile composition is not carried out in order to characterize Tempranillo and Tempranillo Blanco wines. In addition, in the work already published, two vintages were used and, in the present work, three vintages are used. All this has been explained in the Introduction (lines 54-57) and the reference has been added (lines 368-370).
Reviewer 3 Report
The authors responded to all my comments.
Author Response
MANUSCRIPT ID Beverages-1426890
RESPONSE TO REVIEWER 3 AND CHANGES WE HAVE MADE TO THE MANUSCRIPT
Firstly, please accept our thanks for the comments you have made on our paper. Your suggestions have helped to improve the quality of the paper.
The authors responded to all my comments.
Answer: Thank you again.
Author Response File: 
Author Response.docx
