Understanding the Contribution of Co-Fermenting Non-Saccharomyces and Saccharomyces Yeasts to Aroma Precursor Degradation and Formation of Sensory Profiles in Wine Using a Model System
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe manuscript is interesting.
Pg. 2, line 43, Instead “Vitis vinifera” should be “Vitis vinifera L.”
Authors should explain in the manuscript why the assimilable nitrogen (YAN) concentration present in the grape juice was not increased (eg. with nutrients addition) prior the yeasts inoculation.
Author Response
Dear Reviewer, please see the attachment for the authors' responses to your revision. Many thanks for your time and dedication to our manuscript.
Sincerely, Doreen Schober
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsGeneral notes!
The article describes a method of modifying wine aroma profiles by co-fermentation of non-Saccharomyces yeasts with selected (pure) Saccharomyces yeasts and compares it with the results obtained when pure Saccharomyces yeasts were used. A number of fermentation experiments were carried out in various conditions, and the obtained products were subjected to detailed physicochemical, chemical (mainly chromatographic), and sensory analysis. The research concept is innovative and contains many aspects of scientific novelty.
The structure of the article is clear and logical. The research carried out is very well designed and performed, and the results are well documented. The description of the conditions for conducting chemical tests and chromatographic analyzes is very detailed. Too detailed in my opinion. Part of this description could be moved to supplementary materials, which would improve the clarity and compactness of the article. This applies in particular to the following points:
2.4.2 Analysis of yeast cell numbers and fermentation kinetics:
2.5 Chemical analysis of glycosylated aroma precursors
2.5.1 Extraction and enzymatic hydrolysis
2.5.2 GC-MS with SIDA analysis of the hydrolyzed aroma compounds
2.6 Chemical analysis of esters
In the conclusions, the authors write: "By the co-fermentation model setup, it was furthermore disclosed that non-Saccharomyces being protected from Saccharomyces yeasts maintained viable cells much longer than expected, however, albeit prolonged life spans with increased tolerance towards high ethanol and low glucose concentrations, significant contribution to aroma glycoside degradation among non-Saccharomyces strains seems to be rather rare". What does it mean "longer than expected"? This sentence is very long and therefore not clear. Authors should use a few shorter sentences to describe what they have obtained. This will affect the transparency of the conclusions, which are the most important part of the article.
Other comments:
The caption under Figure 5 should be as follows:
Figure 5: Projective mapping of the wines separated the wines by aromas mediated by released glycosidic precursors and yeast-derived esters. Representation of wines with 90% confidence ellipses (A) and descriptors (B), scored by 12 judges (MFA, p ≤ 0.05).
In the bibliography, the authors provide the full names of the scientific journals from which they quote individual articles. Most scientific journals use recognized international abbreviations of journal names.
I found a few typographical errors in the text of the article, which will certainly be removed by responsible editors in the process of preparing the manuscript for publication.
Author Response
Dear Reviewer, please see the attachment for the authors' responses on your comments. Many thanks for your time and dedication spent on our manuscript.
Sincerely, Doreen Schober
Author Response File: Author Response.pdf
