Widely Targeted Metabonomic Analysis to Study Effect of GSH on Metabolites of Chardonnay Wine during Simulated Oxidation

Round 1

Reviewer 1 Report

This manuscript describes a research on effect of addition of gsh on wine storage. Utilization of gsh as an additive of wine is important for the health of consumers and for the wine industry.

This is a well performed and written research.

It elucidates a detailed effect of addition of gsh on wine.

It has a certain novelty.

However there are several points to be addressed.

L44 space should be deleted

Fig1,2,3… fig legends are needed.

Tabel 1-3  fold of increase or decrease should be described.

Sensory evaluations of the wines, if any, will improve the quality of the manuscript.

I did not see a critical problem.

Author Response

L44 space should be deleted

Fig1,2,3… fig legends are needed.

Tabel 1-3  fold of increase or decrease should be described.

Sensory evaluations of the wines, if any, will improve the quality of the manuscript.

Response:

1. Proffessor, do you mean I should delete the sentence “however, it is still in the experimental stage. ”?
2. These diagrams have been with fig legends.
3. I added the fold change in the table and analyzed it in the article.
4. This time, we only studied the effect of different concentrations of GSH on the metabolism of white wine, and Sensory analysis will be conducted in the future.

Reviewer 2 Report

Positive notes to the authors:

1. The topic of the manuscript is relevant as it concerns a metabonomic analysis to investigate the effect of GSH on Chardonnay wine metabolites during simulated oxidation;

2. The authors have tried to describe the achievements of science before their study and to build on scientific and applied studies with one of the most widespread types of wine - Chardonnay. In fact, the innovative idea to replace sulfur dioxide with the reduced tripeptide glutathione is quite original, as avoiding the toxicity and allergenicity of sulfur dioxide;. Although there have been many publications on this topic in the last decade, there is much to be explored in the field of biochemistry and metabolomics specifically for the Chardonnay variety;

3. The Materials and Methods section is relatively detailed, but there is still much to be desired;

4. The results are presented relatively well, and at the same time a biochemical discussion was held, which, however, leaves much to be desired;

5. At the end of the article, the authors have tried to synthesize conclusions that summarize the scientific and applied results of the present study.

Negative notes and recommendations to the authors:

1. At the end of the introduction, the purpose of the study is not clearly specified, which should correspond to the title of the manuscript;

2. It is puzzling why the authors did not investigate the presence of ascorbic acid /vitamin C/ in whey, as it reduces glutathione and maintains a reserve of reducing equivalents in the system. In fact, the primary source of hydrogen is ascorbic acid, which forms a redox system with glutathione;

3. For better visualization, I recommend that the figures be enlarged by 10-15%;

4. In every scientific article, the erudition of the authors is evident in the discussion section. Here, I recommend that the authors dig deeper into the biochemistry of alcohol fermentation and white wine maturation;

5. Despite the relatively extensive conclusions, no specific recommendations were made to the wine industry. Additional studies are probably needed to clarify the dosage and biotechnological application of glutathione in conjunction with another agent (for example, ascorbic acid) to form an optimally functioning oxyreduction system to maintain a pool of reducing equivalents.

Notes on the English language:

Although the article is written in reasonably good English, I recommend a final polish by a specialist English-speaking editor.

Author Response

Point:

1. At the end of the introduction, the purpose of the study is not clearly specified, which should correspond to the title of the manuscript;
2. It is puzzling why the authors did not investigate the presence of ascorbic acid /vitamin C/ in whey, as it reduces glutathione and maintains a reserve of reducing equivalents in the system. In fact, the primary source of hydrogen is ascorbic acid, which forms a redox system with glutathione;
3. For better visualization, I recommend that the figures be enlarged by 10-15%;
4. In every scientific article, the erudition of the authors is evident in the discussion section. Here, I recommend that the authors dig deeper into the biochemistry of alcohol fermentation and white wine maturation;
5. Despite the relatively extensive conclusions, no specific recommendations were made to the wine industry. Additional studies are probably needed to clarify the dosage and biotechnological application of glutathione in conjunction with another agent (for example, ascorbic acid) to form an optimally functioning oxyreduction system to maintain a pool of reducing equivalents.

Response:

1. After modification: The widely targeted metabolomics is the use of UPLC-MS /MS combined with a widely used technique targeted metabolomic technology to analysis non-volatile metabolites in samples and the volatile metabolomics is the use of GC-MS/MS to be employed for the detection of volatile metabolites,due to their fast separation, high sensitivity, and wide coverage.To elucidate the effects of GSH addition on metabolites of Chardonnay wine during storage, herein,we combined the widely targeted metabolomics and volatile metabolomics to study the effects of GSH on  non-volatile components and volatile components of Chardonnay wine under simulated oxidation storage conditions at 45℃.as well as the evolution between these metabolites. This study provides a basisThis study is expected to provide a theoretical reference and objective basis for the application of GSH in white wine.

2-5. You suggested that we could investigate the presence of ascorbic acid /vitamin C/ in wine,yes ,we will l continue our research in this area and also study biotechnological application of glutathione in conjunction with another agent in white wine. In the preliminary experiments ,we found that the combination works better, and we have also entered into an in-depth study on the mechanism.