Optimization of Solid-Phase Lactobacillus Fermentation Conditions to Increase γ-Aminobutyric Acid (GABA) Content in Selected Substrates

Round 1

Reviewer 1 Report

This manuscript entitled “Optimization of solid-phase Lactobacillus fermentation conditions to increase γ-aminobutyric acid (GABA) content in Oryza sativa, Avena sativa, Cicer arietinum, red and brown Lens culinaris” is extremely timely and interesting from the scientific and market point of view. The given information is in this manuscript is useful for researchers and academia and article would be great contribution in discipline of Food Microbiology & Biotechnology.  The room for improvement is always there and I have suggested some major revisions. I can extend my services to further review the incorporation of the corrections in article again.

·         Title : Please reconsider your title

Suggestion- Optimization of solid-phase Lactobacillus fermentation condi- 2 tions to increase γ-aminobutyric acid (GABA) content in selected substrates

·         Abstract-Recheck this statement - . Optimal solid-phase fermentation conditions that 15 could enhance the GABA content after fermenting Oryza sativa(brown rice) were investigated by 16 changing Lactobacillus strain, fermentation temperature, fermentation time, and inoculated bacteria 17 number.

·         Need calrity. When fermented under this condi- 22 tion, GABA content increased up to 49.0% compared to unfermented raw material.

·         Does the functionality  of GABA remain intact in functional food ?( Such solid fermentation conditions developed in 25 this study can be used to support the development of health functional food materials with en- 26 hanced GABA content and antioxidant activit)

·         Cross check reference(P-3) - GABA is involved in nitrogen and carbon metabolism in plants. It acts as an endog- 46 enous signaling factor regulating growth and development. It is widely distributed in var- 47 ious fruits and vegetables and miscellaneous grains such as rice and beans [11

·         P-3 any criteria for selction of variety of rice? Oryza sativa(brown rice) used in this study was cultivated in Naju, Jeollanam-do, Ko- 120 rea, in 2021

·         Reheck- For the production of four types of fermented grains (Avena sativa, Cicer arietinum, 151 red and brown Lens culinaris), L. plantarum and L. casei were diluted with sterile distilled 152 water to a concentration of 1x107 CFU/mL, respectively, and activate at 36℃ for 1 hou

·         Complete this sentence- The HN solution for HN  derivatization was prepared by precisely weighing 0.15 g of HN?

·         Any specific species or strain which give excellent reulsts???? It has been reported that lactic acid bacteria have an excellent  ability to produce GABA. Their ability varies greatly between species and strains

·         The satatment creating no sense - t is widely used as a feed, health food, and alcoholic beverage?

·         Please provide the HPLC peaks (if available with you for better understanding )

·         Cite the following latest papers

o   Sun, X., Wang, J., Li, C., Zheng, M., Zhang, Q., Xiang, W., & Tang, J. (2022). The Use of γ-Aminobutyric Acid-Producing Saccharomyces cerevisiae SC125 for Functional Fermented Beverage Production from Apple Juice. Foods, 11(9), 1202.

o   Ghamry, M., Ghazal, A. F., Al-Maqtqri, Q. A., Li, L., & Zhao, W. (2022). Impact of a novel probiotic Lactobacillus strain isolated from the bee gut on GABA content, antioxidant activity, and potential cytotoxic activity against HT-29 cell line of rice bran. Journal of Food Science and Technology, 59(8), 3031-3042.

o   Ghamry, M., Zhao, W., & Li, L. (2022). Impact of Lactobacillus apis on the antioxidant activity, phytic acid degradation, nutraceutical value and flavor properties of fermented wheat bran, compared to Saccharomyces cerevisiae and Lactobacillus plantarum. Food Research International, 112142.

·         Please avoid repetition-

·         Please check reference style throughout MS

·         Italic all the scientific names,

·         Remove grammatical mistakes

·         Need to rewrite the conclusion

Author Response

Dear reviewer 

Thank you very much for your meticulous paper review. I also pay my respects for cool-headedly finding and pointing out meticulous problems that I hadn't found in the writing of the thesis.
The contents below will send you the answers to the points pointed out by the reviewer. Once again, we ask for your careful efforts.

 

Response to Reviewer 1 Comments

 

We have confirmed the improvement provided by the judges.

 

Thanks for the careful review.

 

 

Point 1:

 Please reconsider your title, Suggestion-optimization of solid-phase Lactobacillus fermentation conditions to increase γ-aminobutyric acid (GABA) content in selected substrates

 

Response 1:

 We have modified the title of the thesis with your suggestion.

 

 

Point 2:

 Abstract-Recheck this statement – Optimal solid-phase fermentation conditions that could enhance the GABA content after fermenting Oryza sativa(brown rice) were investigated by changing Lactobacillus strain, fermentation temperature, fermentation time, and inoculated bacteria number.

 

Response 2:

 We have confirmed the contents, and it is correct to set the optimal fermentation conditions by changing the Lactobacillus strain, fermentation temperature, fermentation time, and bacterial inoculation amount.

 

 

Point 3:

 Need calrity. When fermented under this condition, GABA content increased up to 49.0% compared to unfermented raw material.

 

Response 3:

 We added qualitative GABA content to the content.

 

Line 22~23: Abstract – GABA content increased 4.64 mg/g to 6.93 mg/g (49.0%) compared to unfermented raw material.

 

 

Point 4:

 Does the functionality of GABA remain intact in functional food? (Such solid fermentation conditions developed in this study can be used to support the development of health functional food materials with enhanced GABA content and antioxidant activity.

 

Response 4:

 This study focused on increasing the GABA content in grains using solid fermentation. Additional studies are planned to evaluate the health functional efficacy of grains with increased GABA content.

 

 

Point 5:

 Cross check reference(P-3)-GABA is involved in nitrogen and carbon metabolism in plants. It acts as an endogenous signaling factor regulating growth and development. It is widely distributed in various fruits and vegetables and miscellaneous grains such as rice and beans

 

Response 5:

 The content has been supplemented by referring to the Reference.

 

Line 45~48: GABA is involved in nitrogen and carbon metabolism in plants. GABA in plants plays the role of messengers of enzyme action, regulation of gene expression, and intra- and intercellular transport of intermediates. It is widely distributed in various fruits and vegetables and miscellaneous grains such as rice and beans.

 

 

Point 6:

 P-3 any criteria for selection of variety of rice? Oryza sativa(brown rice) used in this study was cultivated in Naju, Jeollanam-do,Korea, in 2021

 

Response 6:

 Jeollanam-do is the region with the highest rice cultivation area and production in Korea. In addition, Naju City was selected as the grain cultivation site for this study because green areas and forests account for more than 70% of the total area, so that excellent quality Oryza sativa can be steadily supplied in a clean natural environment.

 

 

Point 7:

 Recheck For the production of four types of fermented grains (Avena sativa, Cicer arietinum, red and brown Lens culinaris), L. plantarum and L. casei were diluted with sterile distilled water to a concentration of 1x10⁷ CFU/ml, Respectively, and activate at 36 ℃ for 1 hour

 

Response 7:

 We checked what you mentioned and made sure it was written correctly.

 

 

Point 8:

 Complete this sentence- The HN solution for HN derivatization was prepared by precisely weighting 0.15g of HN?

 

Response 8:

 We have corrected that content.

 

Line 171~173: The HN solution for HN derivatization was prepared by precisely weighing 0.15 g of HN, then it was added into a 50 mL volumetric flask to make 0.3% solution with methanol.

 

 

Point 9:

 Any specific species or strain which give excellent results???? It has been reported that lactic acid bacteria have an excellent ability to produce GABA. Their ability varies greatly between species and strains

 

Response 9:

 According to this study, among 4 types of lactic acid bacteria (L. plantarum, L. casei, L. fermentum and L. rhamnosus), L. plantarum and L. casei showed the highest increase in GABA content in grains.

 

 

Point 10:

 The statement creating no sense- it is widely used as a feed, health food, and alcoholic beverage?

 

Response 10:

We confirmed that the sentence may confuse the reader. It has been modified to the following content.

 

Line 302~303: It is widely used as a raw material for feed, health food, and alcoholic beverages [50].

 

 

Point 11:

 Please provide the HPLC peaks (if available with you for better understanding)

 

Response 11:

 HPLC peaks have been added to Figure 1 for the reader's understanding.

 

 

Point 12:

 Cite the following latest papers

Sun, X., Wang, J., Li, C., Zheng, M., Zhang, Q., Xiang, W., & Tang, J. (2022). The Use of γ-Aminobutyric Acid-Producing Saccharomyces cerevisiae SC125 for Functional Fermented Beverage Production from Apple Juice. Foods, 11(9), 1202.

Ghamry, M., Ghazal, A. F., Al-Maqtqri, Q. A., Li, L., & Zhao, W. (2022). Impact of a novel probiotic Lactobacillus strain isolated from the bee gut on GABA content, antioxidant activity, and potential cytotoxic activity against HT-29 cell line of rice bran. Journal of Food Science and Technology, 59(8), 3031-3042.

Ghamry, M., Zhao, W., & Li, L. (2022). Impact of Lactobacillus apis on the antioxidant activity, phytic acid degradation, nutraceutical value and flavor properties of fermented wheat bran, compared to Saccharomyces cerevisiae and Lactobacillus plantarum. Food Research International, 112142.

 

Response 12:

Thank you for recommending citations related to this study. The contents of the thesis were supplemented by referring to the references.

 

Line 59~61: In a recent study using Saccharomyces cerevisiae, a method for manufacturing a functional fermented apple beverage with increased GABA content by fermenting apple juice was reported [17]. – Sun et al. (2022)

Line 332~334: In recent studies, it has been reported that antioxidant activity and phenolic contents increased when grain by-products were liquid-fermented using Lactobacillus strain [59-61]. – Ghamry et al. (2022)

 

 

Point 13:

 Please avoid repetition

 Please check reference style throughout MS

 Italic all the scientific names.

 Remove grammatical mistakes

 Need to rewrite the conclusion

 

Response 13:

 We reviewed the manuscript again and revised it by referring to the points you pointed out. Modified parts are marked in red.

thank you

Author Response File: Author Response.pdf

Reviewer 2 Report

The manuscript was aimed to optimize the solid-phase Lactobacillus fermentation conditions (temperature, cell concentration and fermentation time) to increase γ-aminobutyric acid (GABA) content in grains. Nowadays, the increasing of GABA concentrations in foods and beverages is of great interest because of beneficial effects of GABA on human health, as it is exhaustively reported in the introduction. The experimental design is sound, analytical methods and statistical analysis are appropriate and the results are clearly written. The conclusions are consistent with the findings obtained.  

The sole recommendation is to update the name of lactobacilli species according to the reclassification reported by Zheng et al., Int. J. Syst. Evol. Microbiol. 2020;70:2782–2858.

Author Response

Dear reviewer 2

Thanks for the careful review.

Below are answers to the details carefully pointed out by the reviewer.

 

Point 1:

 Update the name of lactobacilli species according to the reclassification reported by Zheng et al., Int, J. Syst. Evol. Microbiol. 2020;70;2782-2858.

 

Response 1:

This reference is considered as a reference that can be of great help in sharing information between researchers through subdivision and presenting a new classification system for a wide variety of Lactobacillus species.

 

However, since the lactobacillus species used in this study were purchased from a manufacturer specializing in lactic acid bacteria called Lactomason in South Korea, it is difficult to share detailed information on the origin of lactic acid bacteria.

Later, when conducting research using the bacteria isolated and identified by this institution, the article will be written with reference to the classification system mentioned by the reviewer.

Thank you for providing references that may be helpful for future research.

 

Thank you

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The authors have satisfactorily responded to all my raised  questions and made the necessary changes to the manuscript. My recommendation is to accept this manuscript

Author Response

Dear reviewer 2

I deeply appreciate the reviewer's thoughtful comments and am even more grateful to see a very improved revised file. Also upload the modified file.

Thank you

Author Response File: Author Response.docx