Determination of Changes in Volatile Aroma Components, Antioxidant Activity and Bioactive Compounds in the Production Process of Jujube (Ziziphus jujuba Mill.) Vinegar Produced by Traditional Methods
Round 1
Reviewer 1 Report
You wrote, Vinegar was produced in three replications, and the analyses were performed in two replications. Please clarify how many times the whole experiment has been repeated, and how many times each sample has been analysed. I think you may wrote that you estimated antioxidant activity using Folin assay and ABTS assay.
Author Response
Reviewer 1 respond:
1. Line 92-93: The sentence were changed as “The jujube vinegar production was repeated in two parallel and three replications. All analyzes were carried out in two parallels”.
2. The total phenolic contents (TPC) of the samples were determined in mg GAE/L using the Folin-Ciocalteau method. In addition, the antioxidant activity values of the samples were expressed as mmol TE/L using the 2,2'-azinobis (3-ethylbenzothiazoline)-6-sulfonic acid (ABTS-TEAC) method.
3. Thank you for your contribution.
Author Response File: 
Author Response.docx
Reviewer 2 Report
The authors compared the organic acids, phenolic compounds, and volatile compositions in jujube juice, wine and vinegar in detail. There are the following problems for the authors to consider:
1. There is no production flow chart of jujube wine.
2. Table 3 is too closely arranged to be identified clearly. Figure 2 and 3 are too small to identify the legends.
3. Important experimental phenomena, for example, the content of ascorbic acid increased dramatically in the wine, should be explained.
4. Sugar content and flavor are important indexes for juice, wine and vinegar. I suggest the author to append the related data.
Author Response
Reviewer comments were evaluated and the article was revised. A respond letter to the reviewer is attached. Please see attachment.
Author Response File: Author Response.docx
Reviewer 3 Report
This work gives an detailed investigation on the profiles of phenolic compounds, organic acid, volatile compounds, and antioxidant capacity of jujube juice, wine, and vinegar. The following points to improve the manuscript.
1) Abstract: more detailed results as well as some essential data should be included.
2) Line 13-16: what is the idea of this sentence?
3) In Figure 1, the JW should be jujube wine.
4) Methods: the process for producing jujube juice, wine, and vinegar should be described in detail.
5) Was the crushed jujube and water rested for 1 week to obtain the jujube juice without any treatment? Why?
6) As shown in Figure 1, the jujube juice was adjusted to 12 Bx by adding saccharose. In this sense, it cannot be compared with the literature as listed in Line 158-160.
7) Line 166: where is the result of total soluble dry matter?
8) As shown in Table 3, there was a high level of lactic acid in the jujube juice sample. Where did it come from? As is well known, little lactic acid can be detected in unfermented juice.
9) The most active aroma compounds should be determined by the odor active value (OAV), but not the ratio.
10) Numerous grammatical mistakes and confused sentences existed in the manuscript. Please check them and revised carefully.
Author Response
Reviewer comments were evaluated and the article was revised. A respond letter to the reviewer is attached. Please see attachment.
Author Response File: Author Response.docx
Round 2
Reviewer 3 Report
The authors have revised the manuscript according to the comments. However, there are still some questions in the revised manuscript.
1) In Figure 1, the ' jujube vinegar (JW)' was not corrected.
2) As the jujube fruit is not so juicy, the jujube juice is usually obtained by extracting with water. However, the extracting process in this research was too long, which might cause microbial spoilage due to the growth of bacteria, yeast, and mould. I am curious how to prevent this change when the crushed jujube and water were rested for 1 week without any treatment. The high amount of lactic acid in jujube juice might be the result of fermentation by lactic acid bacteria during the extracting process. Maybe, this research followed a traditional production technique, but it was not an ideal and controllable way. Therefore, some introduction and discussion about the traditional process and the possible effects are necessary to clarify the abovementioned question.
3) Some 'jujuba' in the text (such as line 106) should be replaced with 'jujube'. Please check them out.
Author Response
2nd round questions of the 3rd reviewer have been answered. Please see the attachment.
Author Response File: 
Author Response.pdf
Round 3
Reviewer 3 Report
A minor point:
Line 96: should '10 C' be '10 °C'?
Author Response
Author Respond to Reviewer 3 Comment :
Line 96: It was corrected “10 C” as“10 °C”.
