Production of Functional Vinegar Enriched with γ-Aminobutyric Acid through Serial Co-Fermentation of Lactic Acid and Acetic Acid Bacteria Using Rice Wine Lees

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

this article can be accepted and published in the journal of Applied Microbiology after main revised. there are some questions the author should be ansowered:

(1)the GABA content of vinegar is  very low.  people must drink daily how many functional vinegar to protect action.

(2)the author must add the sensory evaluation of functional vinegar. As a functional food, the taste is very important, otherwise the snstant products is good, the consumer can't accept the product. the product is difficult to enter the market;

(3)the product quality is unstable, the author must consider how to solve and provide some valuable suggestions, othewase the study of this article is of little significance

Comments on the Quality of English Language

English language must be revised 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Thank you for the opportunity to participate in the review of the manuscript titled “Production of functional vinegar enriched with γ-aminobutyric acid through serial co-fermentation of lactic acid and acetic acid bacteria using rice wine lees”

The manuscript talks about the possibilities of preparing vinegar with the help of L. plantarum and A. aceti in the context of GABA production.

 

The introduction of the manuscript is written properly and uses several references. However, the introduction should be supplemented with new publications from recent years (2022-2024). The introduction ends with a clearly stated goal of the work.

The methodology is not described very precisely. It lacks appropriate literature citations that need to be supplemented. You should also add more details in some subsections.

The presented charts and tables are legible and clear. The description of the results is also unquestionable. This chapter is well written.

The conclusions drawn are also well written, referring to the purpose of the work and the results obtained.

A not very large number of publications are presented in the literature list. As mentioned earlier, however, scientific articles need to be refreshed (new publications!)

To sum up, apart from a few things that need to be added, I have no major comments. I believe that the manuscript is suitable for publication in Applied Microbiology. After taking into account the corrections, I recommend the manuscript for further stages of publication.

 

Below are the reviewer's detailed comments.

 

Abstract. Please complete the abstract with the purpose of the work and the method. Additionally, in the abstract you use the full name of the strain L. plantarum, but not A. aceti. Please complete the full name of A. aceti.

Keywords. I suggest changing some keywords to phrases other than those in the manuscript title. The article search engine finds manuscripts based on keywords and titles, so they should not be repeated.

Line 58. Not all Lactiplantibacillus plantarum bacteria are probiotic. This is a strain-dependent feature. You should specify what strain the authors had in mind or rephrase the sentence.

Line 80. The L. plantarum strain was selected based on some research? Have they been published? Does it produce GABA? Please quote.

Line 80, 84. Are the sequences of L. plantarum and A. aceti strains deposited in an international database, for example, Genbank? If so, please provide accession numbers.

Line 82, 83… Please indicate the producers of microbiological media (producer, city, country).

Line 103, 108. Methods should have citations.

Line 120. What is the standard plate count method? Citation needed.

Line 132. Methodology citation needed.

Line 135. What supernatant? How was it received? Please specify.

Line 146, 156. Please specify what filters were used.

Line 200. Table 1 with the results should be located directly below the description. The text should include a reference to table 1.

Line 234-235. The sentence needs to be rephrased.

Line 243-246. Comparing extracts to those produced by L. plantarum is pointless. Please find literature describing the production of GABA by bacteria.

 

One type of font should be used throughout the manuscript and the parenthetical literature citation should be corrected as required.

 

I ask the authors to answer the following questions:

1. What does vinegar prepared in this way taste like?

2. Do you think there is any way to prevent the loss of GABA during storage?

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The manuscript presents an approach to produce GABA-enriched vinegar using rice wine yeast, a byproduct of rice wine production. The study demonstrates the feasibility of this method and provides valuable insights into the factors affecting GABA production and stability. The results have potential applications in the development of functional foods with improved health benefits. The study highlights the temperature-dependent decrease in GABA in fortified vinegar and points to the need for further research to improve its stability. Storage data for GABA contents is limited to five months, which may not be sufficient to fully assess long-term stability.

·         Introduction – Strengthen the connection between rice wine yeast and GABA production. Mention whether there is any existing knowledge about the GABA content in rice wine yeast or the suitability of its components for GABA production by LAB. Explain the concept of serial co-fermentation and why it might be beneficial for this purpose compared to single fermentation. Instead of "without degrading the nutritional components", a more specific hypothesis could be: “while maintaining the functional properties of the rice wine yeast.”

·         Materials and Methods – In section 2.3. For GABA and vinegar production, you could briefly mention the reasons for the chosen percentages for MSG and rice wine in the 1st LAB fermentation.

·         Results and Discussions – Consider condensing repetitive sentences to ensure smoother flow. Mention the statistical analysis methods and p-values ​​used to support the conclusions drawn from the data. Consider adding a concluding paragraph that summarizes the key findings and highlights the novelty of the research.

·         Conclusions – Instead of stating "some negative effects" on acid production, rephrase it to emphasize the optimal concentration (40%) for both GABA and acetic acid production. Mention the activation energy value obtained to support the conclusion. Highlight the final GABA content achieved (2.26%) compared to other studies to demonstrate the effectiveness of the method.

·         Abstract – Replace "serial co-fermentation" with “two-stage serial co-fermentation”. Mention that rice wine yeast, a byproduct, was used for GABA production. Quantify the increase in GABA levels. Mention the GABA level achieved in the finished vinegar (22.61 mg/g) to illustrate the effectiveness. Replace "fortified functional vinegar" with “GABA-enriched vinegar” for better results. Instead of “unstable acid stability,” rephrase it: “evidence of temperature-dependent decrease in GABA”.

 

Comments on the Quality of English Language

Minor editing of English language required.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf