Effect of Starters on Quality Characteristics of Hongsuantang, a Chinese Traditional Sour Soup

Round 1

Reviewer 1 Report

Generally speaking, this topic is interesting and fits the journal well. The authors studies the effects of Hongsuantang starters on its quality characteristics including color, organic acids, total phenols, carotenoids, lycopene, and free radical scavenging ability, which is essential for potential production Hongsuantang. The manuscript can be accepted after minor revisions.

 

Overall, English description could be further improved, such as L27 healthy, traditional and fertemented foods. Moreover, the fonts seems to be not uniform throughout the manuscript.

 

Author affiliation:

Make sure College or School of liquor and food engineering

 

L14 The results showed

L78 chromatographically pure  ??? is not a standard criteria for reagents.

L161, L175 and L201 the equations are not uniform

L228 by 0.77 pH???

L240 pH kept. Similar changes should made across the manuscript.

Figure 1 Since more one Y-axis exists, the color of Y-axis could be changed to make them clearer to read. Also the abbreviations in Figure 1 captions as well as other Figure captions are hard to recognize, please add their full names as well.

 

For Table 2, except for the L a b values, the color difference could be checked to let readers have an overall recognition of the difference between different starters for fermentation.

 

The resolution of Figure 2b could improved.

Check the reference. Some have doi number while some not. Moreover, it seems too many publications have been cited.

Author Response

Q: Overall, English description could be further improved, such as L27 healthy, traditional and fertemented foods. Moreover, the fonts seems to be not uniform throughout the manuscript.

A: Thanks. We have made some modifications.

 

Author affiliation:

Q: Make sure College or School of liquor and food engineering

 A: Thanks. It is College of liquor and food engineering.

L14 The results showed

A: Thanks. We have done so.

L78 chromatographically pure  ??? is not a standard criteria for reagents.

A: Thanks. chromatographically pure has been modified as chromatographic grade

 

L161, L175 and L201 the equations are not uniform

A: Thanks. We have made some modifications.

 

L228 by 0.77 pH???

A: Thanks. We have made some modifications.

 

L240 pH kept. Similar changes should made across the manuscript.

A: Thanks. We have done so.

 

Figure 1 Since more one Y-axis exists, the color of Y-axis could be changed to make them clearer to read. Also the abbreviations in Figure 1 captions as well as other Figure captions are hard to recognize, please add their full names as well.

 A: Thanks. We have done so.

 

Q: For Table 2, except for the L a b values, the color difference could be checked to let readers have an overall recognition of the difference between different starters for fermentation.

A: Thanks. We have done so. ΔE^∗ (total color difference) indicates the total color difference between two samples. When the value of ΔE^∗  is greater than 1, the color difference can be perceived by the human eye. The higher the value, the easier it is to distinguish the difference between colors [1]. Tiwar et al. [2] believe that when the value of ΔE^∗  is more than 3, the color difference between two samples can be clearly distinguished. The effect of fermentation process on the color of red sour soup is shown in Table 1. After fermentation, ΔE^∗  basically increases. During fermentation, the maximum can reach 10.28 ± 0.74 (HBZ25, the 12th day). ΔE^∗  in the control group reached the maximum value on the first day of fermentation, and then kept fluctuating after a period of time, and decreased to 3.48 ± 0.41 at the end of fermentation. Some of the inoculated groups rose to the maximum value first and then remained unchanged until the end of fermentation, such as HBZ11; Some rise to the maximum value in one day of fermentation, and then remain unchanged until the end of fermentation, such as HBB12; Some, such as HBZ25, rise first, then decline, then mutate to the maximum, and then decline at the end of fermentation; Some of them fluctuated after rising and then remained until the end of fermentation, such as HMT-4; Some rise first and then remain unchanged, then suddenly rise to the maximum for a period of time and then decline less, such as HBL1; Some kept rising for a period of time, then reached the maximum and kept for a period of time, and then fell after the end of fermentation, such as HSQ-4; Some, such as HBGS, rise first, then remain for a period of time, then decline, and then rise to the maximum after a period of time, and then decline at the end of fermentation. Therefore, each strain showed its own ΔE^∗ change characteristics. But at the end of fermentation, the inoculation group was significantly higher than the control group, which also showed that the inoculation significantly changed the color of red sour soup. In addition, the color of fermented red sour soup is significantly different from that of unfermented red sour soup (ΔE^∗ >3) [2]. Combined with the changes of L *, a *, and b *, it can be considered that the color of red sour soup is significantly improved by inoculation and fermentation, and the inoculation group is better. Costa. Et al. [3] also find L. casei fermentation improved the color of pineapple juice.

 

 

Q: The resolution of Figure 2b could improved.

A: Thanks. We have done so.

 

Q: Check the reference. Some have doi number while some not. Moreover, it seems too many publications have been cited.

A: Thanks. We have made some modifications. Due to the need to support views and comparative analysis, there are many references

 

 

 

 

1. Tatol, W.M.M. Color difference delta E – A surve. Machine Graphics and Vision 2011, 20.
2. Tiwari, B.K.; Muthukumarappan, K.; O’Donnell, C.P.; Chenchaiah, M.; Cullen, P.J. Effect of ozonation on the rheological and colour characteristics of hydrocolloid dispersions. Food Research International 2008, 41, 1035-1043, doi:10.1016/j.foodres.2008.07.011.
3. Costa, M.G.M.; Fonteles, T.V.; de Jesus, A.L.T.; Rodrigues, S. Sonicated pineapple juice as substrate for L. casei cultivation for probiotic beverage development: Process optimisation and product stability. Food Chemistry 2013, 139, 261-266, doi:10.1016/j.foodchem.2013.01.059.

Reviewer 2 Report

This paper examines the relationship between the starter lactic acid strain and product quality in HST production. I find it interesting for research purposes, but the scientific explanation is not adequate.

- Why did you choose these strains?

- The abstract describes the SQ-4 strain as Lactobacillus plantarum (Line15), but in the 2.2 Starin and starter culture section it is described as Lactobacillus plantaroid (Line86). Which one is correct?

- Isn't Lactobacillus pentosae (Line93) a misspelling of Lactobacillus pentosus?

- A decrease in pH and acid production were also observed in the CON (Figure 1), but do you have any knowledge about what kind of bacteria grow when no starter is added?

- What kind of bacteria are you talking about by harmful bacteria (Line238)?

- Can it be said that fermentation occurred even though viable cell counts did not increase in any of the fermentations a) to h)? (Line272)

- Is the decrease in pH and the increse in acid in the CON caused by wild bacteria (Figure 1)?

- Why did the acidity decrease at the end of fermentation in all fermentations a) to h) (Figure 1)?

- The introduction says that HST is moderate sour (Line32),

If soft sour taste is acceptable (Line506), wouldn't it be better to suppress fermentation by other means than adding lactic acid bacteria starter?

- In the conclusions section, you concluded that SO-4 is excellent starter (Line 544), but physiological properties of SO-4 are not indicated.

Some physiological properties such as acid production capacity, acid resistance, optimal pH for growth, and salt effects etc. should be investigated beforehand, but if no testing has been done, general information on the test strains should be given.

Author Response

Q: This paper examines the relationship between the starter lactic acid strain and product quality in HST production. I find it interesting for research purposes, but the scientific explanation is not adequate.

A: Thanks. We have made some modifications.

Q: - Why did you choose these strains?

A: Thanks. We have made some modifications.

Q: - The abstract describes the SQ-4 strain as Lactobacillus plantarum (Line15), but in the 2.2 Starin and starter culture section it is described as Lactobacillus plantaroid (Line86). Which one is correct?

A：Thanks. It is Lactiplantibacillus plantarum. We have made some modifications.

- Isn't Lactobacillus pentosae (Line93) a misspelling of Lactobacillus pentosus?

A: Yes. We have made some modifications.

Q: - A decrease in pH and acid production were also observed in the CON (Figure 1), but do you have any knowledge about what kind of bacteria grow when no starter is added?

A: Thanks. Some data in the original manuscript are not emphasized or omitted. It should be explained here that the control group is obtained by natural fermentation of pasteurized (70 °C, 15 min) raw materials. While pasteurization removes harmful bacteria, some lactic acid bacteria will remain. We counted the viable bacteria of the pasteurized HST raw materials on the MRS plate, and the number of viable bacteria was 6× 10⁴ CFU/mL. The number of viable bacteria in the control group at the fermentation beginning (day 0) is 4.8 log CFU/mL. MRS is used to count lactic acid bacteria, so there must be some residual lactic acid bacteria in the control group after pasteurization, and they will grow during fermentation. That is consistent with the fact that lactic acid bacteria are the dominant bacteria [1] in the traditional fermentation of HST. In the next step, we will further study microbial community structure changes in the fermentation process of red sour soup with and without microorganisms. In the revised manuscript, we also made corresponding modifications.

Q: - What kind of bacteria are you talking about by harmful bacteria (Line238)?

A: Some may be pseudomonas. In the early stage, we found a certain amount of Pseudomonas in the naturally fermented HST [1]. So, we have made some modifications.

Q: - Can it be said that fermentation occurred even though viable cell counts did not increase in any of the fermentations a) to h)? (Line272)

A: The inoculation concentration here may not be specially emphasized, leading to misunderstanding. Concerning the change in the number of viable bacteria, it should be noted that after pasteurization (70 °C, 15 min), the number of viable bacteria in the control group (HST materials) at the fermentation beginning (day 0) is 4.8 log CFU/mL (6 × 10⁴ CFU/mL, described in Section 2.3 in the revised manuscript). The concentration of seed liquid was adjusted to 1 × 10⁸ CFU/mL (Line 100 in the original manuscript). The inoculation amount is 5% (v/v) (Line 106 in the original manuscript), plus the remaining viable bacteria after pasteurization of raw materials 6 × 10⁴ CFU/mL. The initial (0 days) viable count of raw materials of red sour soup after inoculation is 5.06 × 10⁶CFU/mL, that is, 6.7 log CFU/mL (described in Section 2.3 in the revised manuscript). After one day of fermentation, the number of living bacteria in all the samples increased significantly, and then with further fermentation, the number of living bacteria decreased. Therefore, fermentation must occur. Even in the stage of reducing the number of living bacteria, fermentation will also be carried out because the decline of microorganisms results from the death number being greater than the reproduction number. Even the dead microorganisms would ferment. For example, the cell-free extract of yeast can also ferment [2]. And we have made some modifications.

 

Q: - Is the decrease in pH and the increse in acid in the CON caused by wild bacteria (Figure 1)?

A: Yes. We have made some modifications.

 

Q: - Why did the acidity decrease at the end of fermentation in all fermentations a) to h) (Figure 1)?

A: That may be mainly due to the long fermentation cycle. For example, in the first three days of fermentation, the total acid increased, which was consistent with Yoon's report [3]. In the later stage of fermentation, due to the consumption of nutrients, microorganisms may use some organic acids or convert organic acids into other substances, such as esters, which will decrease total organic acids.

 

Q: - The introduction says that HST is moderate sour (Line32),

If soft sour taste is acceptable (Line506), wouldn't it be better to suppress fermentation by other means than adding lactic acid bacteria starter?

A: Thanks. The expression of soft sour taste is inaccurate. It is a kind of acid that is not very stimulating. So we modified the word. Because the traditional fermented HST is popular, which is mainly fermented by lactic acid bacteria, the other starter, except the lactic acid bacteria, can only be supplemented and coordinated and cannot be the principal strains. Otherwise, we will get another fermented food instead of the traditional HST. Next, we will study the fermentation of HST by lactic acid bacteria and other bacteria.

Q: - In the conclusions section, you concluded that SO-4 is excellent starter (Line 544), but physiological properties of SO-4 are not indicated.

A: Thanks. We have made some modifications. SO-4 may be an excellent potential starter. We added that SQ-4 could reduce cholesterol and nitrite, produce acid quickly, and is acid-resistant and bile-salt resistant. It has an inhibitory effect on Staphylococcus aureus and Escherichia coli. There is no hemolysis on the blood plate and no acute toxicity. When 6% NaCl and 150 mg/kg NaNO2 were added to MRS liquid medium, the growth of SQ-4 was somewhat inhibited, but the growth performance was good [4][citing Song Xiaojuan's master's thesis]. Other characteristics, such as optimal pH value and optimal temperature for growth, will be further studied in the future. Therefore, we have revised the original accordingly.

 

 

Reference:

 

1. Wang, C.; Zhang, Q.; He, L.; Li, C. Determination of the microbial communities of Guizhou Suantang, a traditional Chinese fermented sour soup, and correlation between the identified microorganisms and volatile compounds. Food Research International 2020, 138, 109820, doi:10.1016/j.foodres.2020.109820.
2. Kohler, R.E. The reception of Eduard Buchner's discovery of cell-free fermentation. Journal of the History of Biology 1972, 5, 327-353, doi:10.1007/BF00346663.
3. Yoon, K.Y.; Woodams, E.E.; Hang, Y.D. Probiotication of tomato juice by lactic acid bacteria. Journal of microbiology (Seoul, Korea) 2004, 42, 315-318.
4. Song, X. Screening and performance evaluation of cholesterol-reducing lactic acid bacteria suitable for meat fermentation ( master thesis, in Chinese). Guizhou Univesrsity, 2016.

 

Reviewer 3 Report

The manuscript describes original results regarding the use of selected lactic acid bacteria (LAB) for controlled production of a traditional Chinese soup. Characterization of this soup made with various LAB strains includes microbiological, chemical, and sensory analyses, and uses various adequate techniques. The reference list comprises recent papers. Based on the results, the authors were able to propose one strain as starter for this product, namely Lactiplantibacillus plantarum SQ-4.

However, there are some questions to be answered by the authors:

- they are talking about a "fermentation" with selected bacterial strains, but when we look at Fig. 1, it is obvious that inoculated strains do not grow in the substrate (is it possibly because of the low initial pH?), since the CFU counts do not increase over time, on the contrary, and then the question is: why the pH is decreasing in the beginning? and where is the lactic acid coming from? the explanation given at Lines 239-241 should be therefore adapted;

- on the other hand, the authors do not mention the concentration of inoculum and the CFU at time 0, immediately after inoculation;

- another question is related to the control group, the uninoculated sample: why such a high density of bacteria at start, since no inoculum is used? what kind of bacteria are in the control sample? it may explain the differences in pH values compared to the inoculated samples.

There are also some changes that should be made in the text:

- the names of all species must be written in italics (for instance in the paragraph from Line 275) and adapted to the new rules for Lactobacillus group, for instance: Lactobacillus plantarum is Lactiplantibacillus plantarum, the same with L. pentosus, is Lactiplantibacillus pentosus; please also check the spelling of these names (Material and reagents)

- Line 75: reagents, not regeants

- Line 108: group, not gruop

- Line 113: Is it about the unfermented group, maybe?

- Line 130: please mention what are you measuring with this method (organic acids)

- Line 152: "... a sample was dissolved..."

- Line 152: change the centrifugation speed into g

- Line 199: explain what is the abbreviation OAV standing for

- Lines 268-270: TTA, not TAA 

- Lines 316-318: same phrase as Lines 311-313, is there a mistake?

- there are many phrases that start with "and", please avoid that

- Line 345: "... suggests that a higher..."

- Line 351: content, no contexnt

- Line 366: "inoculation fermentation" - what does it mean?

- Line 368: reference has no number

- Line 376: "changes in DPPH-scavenging effect... fold of increase... was higher (11) than that of... (5.11)"

- Line 378-380: rephrase, since DPPH and ABTS do not have antioxidant activity

- Line 385: reference has no number

- Line 385: "antioxidant substances"

- Line 387: remove "raw"

- Line 390: "reduced the pH", not "produces low pH"

- Table 2: mention on the first line what the numbers represent (days of fermentation)

- Lines 411-412: you should combine the results where the values remained unchanged

- Line 539: "organic acids"

- Line 540: "sensory properties"

- some phrases should be rewritten, for a better understanding: Lines 168, 228-231, 256, 335-336, 372-375, 390-392, 542

 

Author Response

Q: - they are talking about a "fermentation" with selected bacterial strains, but when we look at Fig. 1, it is obvious that inoculated strains do not grow in the substrate (is it possibly because of the low initial pH?), since the CFU counts do not increase over time, on the contrary, and then the question is: why the pH is decreasing in the beginning? and where is the lactic acid coming from? the explanation given at Lines 239-241 should be therefore adapted;

A: The inoculation concentration may not be specially emphasized, which was 8.0 log CFU/mL (Line 100 in the original manuscript), leading to misunderstanding. Concerning the change in the number of viable bacteria, it should be noted that after pasteurization (70 °C, 15 min), the number of viable bacteria in the control group (HST materials) at the fermentation beginning (day 0) is 4.8 log CFU/mL (6 × 10⁴ CFU/mL, described in Section 2.3 in the revised manuscript). The concentration of seed liquid was adjusted to 1 × 10⁸ CFU/mL (Line 100 in the original manuscript). The inoculation amount is 5% (v/v) (Line 106 in the original manuscript), plus the remaining viable bacteria after pasteurization of raw materials 6 × 10⁴ CFU/mL. The initial (0 days) viable count of raw materials of red sour soup after inoculation is 5.06 × 10⁶CFU/mL, that is, 6.7 log CFU/mL (described in Section 2.3 in the revised manuscript). After one day of fermentation, the number of living bacteria in all the samples increased significantly, and then with further fermentation, the number of living bacteria decreased. Therefore, fermentation must occur. Even at reducing the number of living bacteria, fermentation will also be carried out because the decline of microorganisms results from the death number being greater than the reproduction number. Even the dead microorganisms would ferment. For example, the cell-free extract of yeast can also ferment [1]. And we have made some modifications. Therefore, with the fermentation of lactic acid bacteria, lactic acid will be produced, and the pH will decrease. We have made corresponding modifications in the revised version.

 

Q: - on the other hand, the authors do not mention the concentration of inoculum and the CFU at time 0, immediately after inoculation;

A: Thanks. We have made some modifications.

 

Q: - another question is related to the control group, the uninoculated sample: why such a high density of bacteria at start, since no inoculum is used? what kind of bacteria are in the control sample? it may explain the differences in pH values compared to the inoculated samples.

A: Some data in the original manuscript are not emphasized or omitted. Although the control group was not inoculated, the control group was pasteurized (70 °C, 15 min) rather than sterilized, mainly killing harmful microorganisms but also causing the death of some beneficial microorganisms, but certainly some microorganisms will survive. We counted the viable bacteria of the pasteurized HST raw materials on the MRS plate, and the number of viable bacteria was 6× 10⁴ CFU/mL. The number of viable bacteria in the control group at the fermentation beginning (day 0) is 4.8 log CFU/mL. MRS is used to count lactic acid bacteria, so there must be some residual lactic acid bacteria in the control group after pasteurization, and they will grow during fermentation. That is consistent with the fact that lactic acid bacteria are the dominant bacteria [2] in the traditional fermentation of HST. At first, the number of viable bacteria was not high, only 4.8 log CFU/mL, but after one day of fermentation, it multiplied to the maximum. The lactic acid bacteria in the control group grew fast, but their acid production performance was not as good as that of lactic acid bacteria inoculated. That resulted in different pH values for fermentation of the remaining inoculated strains. In the next step, we will further study microbial community structure changes in the fermentation process of red sour soup with and without microorganisms. In the revised version, we also made corresponding modifications.

 

There are also some changes that should be made in the text:

Q: - the names of all species must be written in italics (for instance in the paragraph from Line 275) and adapted to the new rules for Lactobacillus group, for instance: Lactobacillus plantarum is Lactiplantibacillus plantarum, the same with L. pentosus, is Lactiplantibacillus pentosus; please also check the spelling of these names (Material and reagents)

A: Thanks. We have done so.

Q: - Line 75: reagents, not regeants

A: Thanks. We have done so.

 

Q: - Line 108: group, not group

A: Thanks. We have done so.

 

Q: - Line 113: Is it about the unfermented group, maybe?

A: Thanks. Yes. We have made some modifications.

 

Q: - Line 130: please mention what are you measuring with this method (organic acids)

A: Thanks. We have done so.

 

Q: - Line 152: "... a sample was dissolved..."

A: Thanks. We have done so.

 

Q: - Line 152: change the centrifugation speed into g

A: Thanks. We have done so. The original data is missing a 0, which has also been modified in the revised manuscript.

 

Q: - Line 199: explain what is the abbreviation OAV standing for

A: Thanks. The abbreviation OAV stands for odor activity value. Then, we made some modifications.

Q: - Lines 268-270: TTA, not TAA 

A: Thanks. We have done so.

 

Q: - Lines 316-318: same phrase as Lines 311-313, is there a mistake?

A: Yes. We deleted the Lines 316-318.

 

Q: - there are many phrases that start with "and", please avoid that

A: Thanks. We have made some modifications.

 

Q: - Line 345: "... suggests that a higher..."

A: Thanks. We have done so.

 

Q: - Line 351: content, no contexnt

A: Thanks. We have done so.

 

Q: - Line 366: "inoculation fermentation" - what does it mean?

A: We deleted the fermentation.

 

Q: - Line 368: reference has no number

A: Thanks. We added the reference number.

 

Q: - Line 376: "changes in DPPH-scavenging effect... fold of increase... was higher (11) than that of... (5.11)"

A: Thanks. We have done so.

Q: - Line 378-380: rephrase, since DPPH and ABTS do not have antioxidant activity

A: Thanks. We have done so.

 

Q: - Line 385: reference has no number

A: The reference number is at the end of the sentence. Then, We moved it to the front.

 

Q: - Line 385: "antioxidant substances"

A: Thanks. We have done so.

 

Q: - Line 387: remove "raw"

A: Thanks. We have done so.

 

Q: - Line 390: "reduced the pH", not "produces low pH"

A: Thanks. We have done so.

 

Q: - Table 2: mention on the first line what the numbers represent (days of fermentation)

A: Thanks. We have done so.

 

Q: - Lines 411-412: you should combine the results where the values remained unchanged

A: Thanks. We have done so.

 

Q: - Line 539: "organic acids"

A: Thanks. We have done so.

 

Q: - Line 540: "sensory properties"

A: Thanks. We have done so.

 

Q: - some phrases should be rewritten, for a better understanding: Lines 168, 228-231, 256, 335-336, 372-375, 390-392, 542

A: Thanks. We have made some modifications.

The section “Line 168: In brief, 5 mL of ABTS solution (7 mmol/L H₂O) and 90 mL of (NH₄)₂S₂O₈ (140 mmol) were placed at room temperature for 16 h. The solution was diluted with ethanol until the absorbance value of 0.70 ± 0.02 at 734 nm “ has been modified as follows: In brief, 5 mL of ABTS solution (7 mmol/L H₂O) and 90 mL of (NH₄)₂S₂O₈ (140 mmol) were mixed and left overnight (16 h) in the dark at room temperature. The obtained ABTS˙⁺ radical solution was diluted with methanol, to check its absorbance of 0.70 ± 0.02 at 734 nm.

The section “Line 228-331: Another interesting phenomenon is that after one day of fermentation, the pH of the inoculated group dropped to the lowest significantly, basically equation to that of the 15-day fermentation, but HBGS, which continued to decrease significantly on the third day of HBGS fermentation, slightly less than that on the first day” have been modified as follows: Another interesting phenomenon is that after one day of fermentation, the pH of the inoculated group dropped to the lowest significantly and basically kept unchanged to the 15^th day fermentation, but HBGS. The pH of HBGS increased on the first day, then continued to decline to the lowest on the third day of fermentation, and was basically kept unchanged to the 15^th day.

The section “Line 256: Because of the lack of fructooligosaccharide, the result was lower than 59.00 ± 0.17 g/kg reported by Koh et al. [3]” has been modified as follows: Because of the lack of fructooligosaccharide, the maximum acid production was lower than 59.00 ± 0.17 g/kg reported by Koh et al. [3].

 

The section “Line 335-336: Still, there was no significant difference in the total phenols content in HST (P > 0.05) after fermentation but HBGS” has been modified as follows: Still, the total phenol contents of different HST but HBGS were insignificant (P > 0.05).

 

The section “Line 372-375: For ABTS, the fermented group was much higher than the unfermented group (18.83), and the inoculated group was significantly higher than the control group (73.94). The highest was HBZ25, HMT-4, HSQ-4 and HBGS, and the highest value was around 84” has been modified as follows: The ABTS radical scavenging capacity of the fermented group was much higher than the unfermented group (18.83%), and that of the inoculated group was significantly higher than the control group (73.94%). HBZ25, HMT-4, HSQ-4, and HBGS had the highest ABTS radical scavenging capacity, and the highest value was around 84%.

 

The section “Line 390-392: The fermentation of lactic acid bacteria inoculated in this study produced Low pH, contributed to the total phenols and carotenoids release and helped ABTS radical scavenging capacity and DPPH radical scavenging capacity performance enhancement” has been modified as follows: The lactic acid bacteria inoculated in this study reduced pH, which contributed to the total phenols and carotenoids release, and improved ABTS radical scavenging capacity and DPPH radical scavenging capacity.

 

The section “Line 542: vital aroma compounds in HST fermentation by the starter” has been modified as follows: vital aroma compounds in the inoculated HST.

 

Reference:

1. Kohler, R.E. The reception of Eduard Buchner's discovery of cell-free fermentation. Journal of the History of Biology 1972, 5, 327-353, doi:10.1007/BF00346663.
2. Wang, C.; Zhang, Q.; He, L.; Li, C. Determination of the microbial communities of Guizhou Suantang, a traditional Chinese fermented sour soup, and correlation between the identified microorganisms and volatile compounds. Food Research International 2020, 138, 109820, doi:10.1016/j.foodres.2020.109820.
3. Koh, J.H.; Kim, Y.; Oh, J.H. Chemical characterization of tomato juice fermented with bifidobacteria. Journal of Food Science 2010, 75, C428-432, doi:10.1111/j.1750-3841.2010.01632.x.

Round 2

Reviewer 2 Report

Manuscript has been improved according to my comments.

 

 

Author Response

Thanks.

Reviewer 3 Report

The authors made most of the recommended changes. However, there are still some minor changes to be made:

General comments:

- the species names are still not correct: Lactobacillus bulgaricus remained unchanged after the new recommendation, it is not Lactiplantibacillus; also L. rhamnosus is Lacticaseibacillus rhamnosus;

- after you used the full names, you can further use the abbreviation, such as "L.", for all lactobacilli, "B" for Bifidobacterium;

- decide what you want to use: log CFU/ml or CFU/ml and use the same style throughout the manuscript;

- my suggestion for the future studies is that the whole process of fermentation should be also followed in detail in the first 24h (3, 6, 9, 12 h), since there is the most important change in cell numbers and pH, perhaps other changes as well.

Other comments:  

- L. 83: when you first use LAB you should write lactic acid bacteria (LAB)

- L. 99: L. plantaroid?

- L. 108: what do you mean by that?

- L. 109-113: it is not necessary to repeat all the names

- L. 125, you repeat "pasteurization", try to replace or rephrase

- L. 124-130: I suggest to change as follows: "It should be noted here that after pasteurization, the number of viable bacteria was 4.8 log CFU/ml on MRS agar medium. (remaining viable bacteria). The initial viable counts of HST after inoculation was about 6.7 log CFU/ml, representing both the inoculated and remaining viable bacteria.  

- L. 132-133: "the initial viable counts of CON group after pasteurization was 4.8 log CFU/ml"

- L138-139: "The unfermented group and fermented group were both analyzed

- L. 198: it is not clear what is "mixture A"

- L. 259: "inoculated group, except HBGS"

- L. 260: delete "but HBGS"

- L. 268-280: do not repeat all information given in Materials and Methods

- L 299: "the same below"?

- L 349: "with and without added bacterial inoculum"

- L 395-396: perhaps you wanted to say "the differences were insignificant"?

- L 435: "scavenging capacity of"

- L 439: "DPPH scavenging effect"

- L 441: you can say "differences among samples in the inoculated group were not significant"

- L. 442-443: "That shows that DPPH and ABTS radical scavenging capacities are not consistent..."

- L 446: "fermentation by LAB can enhance"

- L 454: delete "the"

- L 505: "increased.." and "reached.."

- L 505-526: if only one product shows a characteristic, do not use "some of the groups..", use the sample name/code; the whole paragraph is difficult to follow, it does not contain any value of the parameters, just "maximum", "minimum", "decline" etc.; please summarize the most important findings of this experiment in 2-3 phrases

- L 626: "previous"

Table 1: "the same below"?; UNF indicated... delete "thant"

- L 645: "inoculated fermented HST"?

 

Author Response

Q: - the species names are still not correct: Lactobacillus bulgaricus remained unchanged after the new recommendation, it is not Lactiplantibacillus; also L. rhamnosus is Lacticaseibacillus rhamnosus;

A: Thanks. We have done so.

Q: - after you used the full names, you can further use the abbreviation, such as "L.", for all lactobacilli, "B" for Bifidobacterium;

A: Yes.

Q: - decide what you want to use: log CFU/ml or CFU/ml and use the same style throughout the manuscript;

A: Thanks. We have made some modifications.

Q: - my suggestion for the future studies is that the whole process of fermentation should be also followed in detail in the first 24h (3, 6, 9, 12 h), since there is the most important change in cell numbers and pH, perhaps other changes as well.

A: Yes. Thank you for your suggestion.

Other comments:  

Q: - L. 83: when you first use LAB you should write lactic acid bacteria (LAB)

A: Yes, please see Line 43.

Q: - L. 99: L. plantaroid?

A: Thanks. We modified it.

Q: - L. 108: what do you mean by that?

A: Thanks. The sentence “Commercial strains BL1 and strains have strong acid production capacity “ has been modified as “Commercial strains BL1 and Q-1 have a strong acid production capacity”.

Q: - L. 109-113: it is not necessary to repeat all the names

Q: - L. 125, you repeat "pasteurization", try to replace or rephrase

A: Thanks. We have made some modifications.

Q: - L. 124-130: I suggest to change as follows: "It should be noted here that after pasteurization, the number of viable bacteria was 4.8 log CFU/ml on MRS agar medium. (remaining viable bacteria). The initial viable counts of HST after inoculation was about 6.7 log CFU/ml, representing both the inoculated and remaining viable bacteria.  

A: Thanks. We have done so.

Q: - L. 132-133: "the initial viable counts of CON group after pasteurization was 4.8 log CFU/ml"

A: Thanks. We have done so.

Q: - L138-139: "The unfermented group and fermented group were both analyzed

A: Thanks. We have done so.

 

Q: - L. 198: it is not clear what is "mixture A"

A: We have modified it.

Q: - L. 259: "inoculated group, except HBGS"

A: Thanks. We have done so.

 

Q: - L. 260: delete "but HBGS"

A: Thanks. We have done so.

 

Q: - L. 268-280: do not repeat all information given in Materials and Methods

A: Thanks. We deleted some of them.

Q: - L 299: "the same below"?

A: Thanks. We have made some modifications.

Q: - L 349: "with and without added bacterial inoculum"

A: Thanks. We have done so.

Q: - L 395-396: perhaps you wanted to say "the differences were insignificant"?

A: Yes. We have made some modifications.

Q: - L 435: "scavenging capacity of"

A: Yes.

Q: - L 439: "DPPH scavenging effect"

A: Thanks. We have done so.

 

Q: - L 441: you can say "differences among samples in the inoculated group were not significant"

A: Thanks. We have done so.

 

Q: - L. 442-443: "That shows that DPPH and ABTS radical scavenging capacities are not consistent..."

A: Thanks. It is Ok.

 

Q: - L 446: "fermentation by LAB can enhance"

A: Thanks. We have done so.

 

Q: - L 454: delete "the"

Thanks. We have done so.

 

Q: - L 505: "increased.." and "reached.."

A: Thanks. We have done so.

 

Q: - L 505-526: if only one product shows a characteristic, do not use "some of the groups..", use the sample name/code; the whole paragraph is difficult to follow, it does not contain any value of the parameters, just "maximum", "minimum", "decline" etc.; please summarize the most important findings of this experiment in 2-3 phrases

A: Thanks. We have made some modification.

Q: - L 626: "previous"

A: Thanks. We have modified it.

 

Q: Table 1: "the same below"?; UNF indicated... delete "thant"

A: Thanks. We have modified them.

 

Q: - L 645: "inoculated fermented HST"?

 A: Thanks. We have modified it.