Influence of Native Saccharomyces cerevisiae Strains from D.O. “Vinos de Madrid” in the Volatile Profile of White Wines
, Braulio Esteve-Zarzoso 2, Julia Crespo 1, Juan Mariano Cabellos 1 and Teresa Arroyo 1Round 1
Reviewer 1 Report
This manuscript deals with the volatile profile of white wines fermented with native yeast isolated from different cellars. The research topic was interesting, but the results of the paper were plain. I have the following questions or comments for the authors.
Major considerations
Title: The purpose of this study was to reveal different volatile profiles of white wines fermented with native yeasts isolated from different cellars. Consider revising the title to reflect your research topic.
Abstract: Abstract should be described with a focus on results rather than on introduction.
Introduction: Introduction is too long. There are many parts that are not directly related to the research topic, which blurs the topic. Please describe concisely, focusing on the key topic. Rational hypotheses based on scientific facts should be set up and the studies should be conducted centering on them.
Materials and Methods: There is a lack of information on how to make wine. Depending on the method for wine making, the volatile profile of wine may be different. Is there a reason authors used grapes harvested in 2010? Was winemaking done in the same place and in the same way? Maturation of wine can also affect the results of volatile profile. Also, are all yeasts used in the experiment identified as Saccharomyces cerevisiae? This is very important and needs to be checked.
Result and Discussion: The explanation of the manuscript is difficult to understand. The entire section requires significant improvement. Discussion should focus on the causes or meaning of the findings. Why do the authors think the aroma profile of white wine is different by cellar of origin? It is important to consider the cause of the results (aroma profile) rather than interpret the results correlated with ODE or OAV. A discussion is necessary in connection with different yeast species or origins. I recommend that authors fully revise the discussion to reflect this.
Minor considerations
Line 17&98: Please check the number of yeast.
Line 131: How did the identification of volatile components proceed?
Author Response
Major considerations
The changes suggested by reviewers have been highlighted in yellow.
A native English speaker has revised the manuscript and we have added some grammatical changes, which are highlighted in blue.
Point 1: Title: The purpose of this study was to reveal different volatile profiles of white wines fermented with native yeasts isolated from different cellars. Consider revising the title to reflect your research topic.
Response 1: We have changed the title for -Influence of Native Saccharomyces cerevisiae Strains from D.O. “Vinos de Madrid” in the Volatile Profile of White Wines- in order to better reflect the importance of native Saccharomyces cerevisiae yeasts in this article.
Point 2: Abstract: Abstract should be described with a focus on results rather than on introduction.
Response 2: Results have been added to the abstract.
Point 3: Introduction: Introduction is too long. There are many parts that are not directly related to the research topic, which blurs the topic. Please describe concisely, focusing on the key topic. Rational hypotheses based on scientific facts should be set up and the studies should be conducted centering on them.
Response 3: Introduction have been summarized and it is more linked to the new title.
Point 4: Materials and Methods: There is a lack of information on how to make wine. Depending on the method for wine making, the volatile profile of wine may be different. Is there a reason authors used grapes harvested in 2010? Was winemaking done in the same place and in the same way? Maturation of wine can also affect the results of volatile profile. Also, are all yeasts used in the experiment identified as Saccharomyces cerevisiae? This is very important and needs to be checked.
Response 4: We have added more detailed information on wine elaboration (lines 100-113). The winemaking process is the same for all Saccharomyces strains to ensure that aromatic differences are only related to the yeast strain employed. In addition, after wine fermentation, all samples were clarified and frozen immediately to avoid different maturation periods which may affect the volatile profile.
We used this must because we only had enough frozen must for winemaking from this 2010 harvest. We would like to remark that more than 100 L of must were needed to perform this project. Furthermore, we decided use the same must for all fermentations in order to prevent possible deviations due to the year of vintage. Also, we could control the reproducibility of trials, adjusting the must parameters to those indicated in the manuscript (lines 103-106).
Finally, all strains were identified as different S. cerevisiae genotypes using microsatellites multiplex PCR analysis. We specified this information in lines 96-99. The article of Tello et al. [34] contains additional information about this work of identification.
Point 5: Results and Discussion: The explanation of the manuscript is difficult to understand. The entire section requires significant improvement. Discussion should focus on the causes or meaning of the findings. Why do the authors think the aroma profile of white wine is different by cellar of origin? It is important to consider the cause of the results (aroma profile) rather than interpret the results correlated with ODE or OAV. A discussion is necessary in connection with different yeast species or origins. I recommend that authors fully revise the discussion to reflect this.
Response 5: Please, we would like to know those parts of the manuscript difficult to understand in order to improve them.
According to the discriminant statistical analysis, we can observe that the volatile composition of wines classified them in a correct way (86.7%) by cellar of origin. But we have not affirmed that the wine aroma is different depending on cellar. However, wines presented similar aroma descriptors using Saccharomyces strains from different cellars (as can be seen in PCA analysis).
The OAV parameter is usually used to estimate the sensory contribution of aromatic compounds to the overall aroma of wine. We consider necessary to include some OAV values of volatiles to remark differences between wine samples and, to suggest the main contribution of some volatiles to determined descriptors.
To improve the results obtained, some references have been added to the discussion in agreement with our results, connecting yeasts with their origin.
Minor considerations
Line 17&98: Please check the number of yeast.
Response: The number of yeast strains indicated in both lines is correct. On the line 17, 102 Saccharomyces cerevisiae strains involve the 101 strains isolated from six vineyards and cellars studied (A to F), and the control strain (Saccharomyces cerevisiae CLI 889). Moreover, all these strains are belonging to D.O. “Vinos de Madrid”. On the other hand, in materials and methods section (lines 84-93), we explained separately the origin of the 101 Saccharomyces strains from cellars and the control strain.
Line 131: How did the identification of volatile components proceed?
Response: The main procedures of the volatile analysis are indicated on lines 115 to 121, all of them following the same methodology described by Ortega et al. 2001 [37].
Identification and quantification of the 31 individual major volatiles was done by the use of commercial pure standards. Calibration curves were drawn for each standard at four different concentration levels. Quantification was based on five-point calibration curves of respective standards in a synthetic wine solution (5 g/L of tartaric acid, dissolved in 13% of ethanol solution (v/v), at pH 3.4 adjusted with NaOH). The obtained coefficients of regression (R2) were >0.990.
As the methodology has already been published in a well-recognized journal, we do not include more data about this. We used the same procedure in other publications of our research group, but not more information was included. However, if the reviewer feels that more details should be added (although the research topic is about the results obtained, not the method used), we will include it.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The work is very interesting, it fits in with scientific trends, needed in practical terms. The research methodology was planned correctly. The results of the described tests were presented correctly, statistically evaluated.
Only the conclusions are written too briefly in relation to the results obtained. I propose to further refine them with an indication of the best possible option for commercial use.
Author Response
The work is very interesting, it fits in with scientific trends, needed in practical terms. The research methodology was planned correctly. The results of the described tests were presented correctly, statistically evaluated.
Only the conclusions are written too briefly in relation to the results obtained. I propose to further refine them with an indication of the best possible option for commercial use.
The changes suggested by reviewers have been highlighted in yellow.
A native English speaker has revised the manuscript and we have added some grammatical changes, which are highlighted in blue.
Conclusions have been improved and a short phrase about the commercial possibility of Saccharomyces strains has been added.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The content of the manuscript has been improved. However, in Introduction and Results and Discussion sections, there are still many parts that are not directly related to the research topic, which blurs the topic.
Introduction section should identify the recent research trends related to the research topic and explain why this study was conducted. The purpose of this study was to investigate the impact of “S. cerevisiae strains” isolated from their oenological region on the “volatile composition” of Malvar wines. Result and Discussion section should focus on the causes or meaning of the findings in relation to the research topic. I understand that the OAV parameter is important to estimate the sensory contribution of aromatic compounds to the overall aroma of wine. But OAV is just a tool for interpreting the author's results. I think Table 1 is a supplementary data. A discussion is necessary in connection with “different yeast species” or “origins”. If 101 natural S. cerevisiae yeast strains have been isolated and identified, clustering is expected according to genotype. If there are any results about the genetic association between identified yeasts, please provide them. line 261: “5 conclusions” should be changed to “4 conclusions”.
