Improved Functions of Fermented Coffee by Lactic Acid Bacteria

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Manuscript: "Improved Functions of Fermented Coffee by Lactic Acid Bacteria"

 The manuscript presents a study on the benefits of fermenting coffee extracts using specific strains of lactic acid bacteria. It describes how these strains enhance various functional properties of fermented coffee, including antimicrobial and antioxidant activities. Below are some suggestions that could improve the quality of the manuscript:

 Lines 13-25: Specify the statistical significance of the obtained results.

 Lines 81-89: Include recent studies on advances in coffee fermentation to demonstrate the relevance of the topic.

 Lines 90-93: Add a brief explanation on the importance of selecting specific LAB strains and their relevance in coffee fermentation.

 Lines 342-389: Provide a more in-depth discussion on how increased acidity affects the sensory properties of coffee. Additionally, explain the implications of increased biomass in terms of the viability and stability of the final product.

 - Explain the possible metabolic pathways involved in caffeine degradation by lactic acid bacteria. Also, describe how the increase in chlorogenic acid might influence consumer health and coffee properties. Provide comparisons with other studies that have observed similar or different effects.

 - Provide specific examples of how these results can be utilized in the coffee industry, such as the development of new fermented coffee products with enhanced functional properties. Additionally, suggest directions for future research, such as investigating other bioactive compounds that may be affected by LAB fermentation and the sensory evaluation of the final product by consumers.

Comments on the Quality of English Language

No comments

Author Response

Reviewer 1

 

The manuscript presents a study on the benefits of fermenting coffee extracts using specific strains of lactic acid bacteria. It describes how these strains enhance various functional properties of fermented coffee, including antimicrobial and antioxidant activities. Below are some suggestions that could improve the quality of the manuscript:

• Thanks for the valuable comments and we corrected as your comments.

Lines 13-25: Specify the statistical significance of the obtained results.

• We have mentioned the statistical significance for the results. The results were statistically analyzed through ANOVA and Duncan’s multiple range test (p<0.05) for host-hoc.

Lines 81-89: Include recent studies on advances in coffee fermentation to demonstrate the relevance of the topic.

• We have added recent references for the coffee fermentation (line 100-line 108) as well as for coffee itself (line 83-94).

Lines 90-93: Add a brief explanation on the importance of selecting specific LAB strains and their relevance in coffee fermentation.

• We already explained why those strains were chosen in Materials and Methods (2.1) but the reason was simply mentioned in the sentence for clarification (line 118).

Lines 342-389: Provide a more in-depth discussion on how increased acidity affects the sensory properties of coffee. Additionally, explain the implications of increased biomass in terms of the viability and stability of the final product.

• We discussed how acidity can alter the sensory profile of the coffee both in positive and negative ways (line 378-386). In this study biomass data were used only the growth evidences in the coffee extract for the selected strains and viable cells are rarely existed in the final product since they are exposed to high temperature during spray-drying.

 Explain the possible metabolic pathways involved in caffeine degradation by lactic acid bacteria. Also, describe how the increase in chlorogenic acid might influence consumer health and coffee properties. Provide comparisons with other studies that have observed similar or different effects.

• We discussed possible mechanisms for caffeine degradation by lactic acid bacteria (line 441-451) and for increased chlorogenic acid content in the fermented coffee extract (line 407-413). We also discussed health benefits of increased chlorogenic acid in the extract (line 419-424).

Provide specific examples of how these results can be utilized in the coffee industry, such as the development of new fermented coffee products with enhanced functional properties. Additionally, suggest directions for future research, such as investigating other bioactive compounds that may be affected by LAB fermentation and the sensory evaluation of the final product by consumers.

• We mentioned the uses of the fermented coffees in coffee industry and future research direction through Conclusions section.

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

The study on Improved functions of fermented coffee by lactic acid bacteria is an interesting one, I congratulate the authors for this idea.

It is very interesting selection of coffee extract resistant LAB strains, to isolate coffee extract-resistant LAB, approximately 450 strains were tested a very ok research

Recomand autorilor analize mai complexe folosind tehnici de analiza HPLC, avand in vedere ca s-a determinat increased anti-oxidation activity of fermented coffee extract, de ce nu ati determinat si continutul de polifenoli?

 

 

Author Response

Reviewer 2

 

The study on Improved functions of fermented coffee by lactic acid bacteria is an interesting one, I congratulate the authors for this idea.

It is very interesting selection of coffee extract resistant LAB strains, to isolate coffee extract-resistant LAB, approximately 450 strains were tested a very ok research.

Recomand autorilor analize mai complexe folosind tehnici de analiza HPLC, avand in vedere ca s-a determinat increased anti-oxidation activity of fermented coffee extract, de ce nu ati determinat si continutul de polifenoli?

• Thanks for the valuable comments. Unfortunately we did not analyze the content of total phenolic compounds in this study since we only focused on main phenolic compounds in coffee such as caffeine and chlorogenic acid. Please understand it. However in the future study, we will definitely analyze other phenolic compounds in the fermented coffees as well as the content of total phenolic compounds.

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

After reviewing this manuscript, there are several concerns that come to mind:

1. From paragraphs 90-91, it is understood that a pre-mixed coffee extract (50% Arabica + 50% Robusta) was directly used, but the manuscript does not provide an explanation for this choice. The primary reason for selecting this specific ratio of extract is not discussed, and its representativeness has not been validated.
2. In paragraphs 220-224, three strains of lactic acid bacteria (Pediococcus pentosaceus KNUT 0384, Lacticaseibacillus paracasei CJNU 1840, Lactiplantibacillus plantarum CJNU 0441) were selected for the fermentation of the coffee extract. The manuscript does not elaborate on why these specific strains were chosen, nor does it discuss whether they possess known characteristics related to coffee fermentation; it merely states that "approximately 450 strains were tested" and these three showed strong antimicrobial activity.
3. The manuscript mentions an increase in the antioxidant and antimicrobial activities of the fermented coffee extract, but it does not provide direct comparative data with the non-fermented coffee extract.

Reviewer's comments:

1. It is recommended that the authors provide more background information on the selected strains of lactic acid bacteria and why they are suitable for coffee fermentation.
2. Control data for the non-fermented coffee extract should be provided to more accurately assess the impact of the fermentation process.
3. Specific P-values should be provided, and a discussion of whether the data meets the prerequisites for ANOVA analysis should be included.
4. More rationale or literature support should be provided for the ratio of coffee extract used in the experiment.
5. It is suggested that the experimental results be discussed in more depth, particularly regarding the mechanisms behind the observed decrease in caffeine content and increase in chlorogenic acid content during fermentation.
6. It is recommended that the conclusion section provide more discussion on the practical implications of these findings for the potential application in the specialty coffee industry.

As a manuscript intended for publication, it is hoped that more experimental details and data will be provided. The research and thought process regarding coffee should be more in-depth. After all, using a coffee extract produced by a specific company for the experiment makes it difficult to convince readers that this study has reference and representative significance.

Comments on the Quality of English Language

Minor editing of English language required.

Author Response

Reviewer 3

 

After reviewing this manuscript, there are several concerns that come to mind:

• Thanks for the valuable comments and we responded about your queries or corrected as your comments.

1. From paragraphs 90-91, it is understood that a pre-mixed coffee extract (50% Arabica + 50% Robusta) was directly used, but the manuscript does not provide an explanation for this choice. The primary reason for selecting this specific ratio of extract is not discussed, and its representativeness has not been validated.

• We have mentioned the reason of using 50% Arabica and 50% Robusta coffee in Introduction section (lines 83-94). Arabica (Coffea arabica L.) and Robusta (Coffea canephora) are two economically significant coffee species. Arabica is renowned for its aromatic and sweet characteristics, as well as its notable variations in acidity and flavor. In contrast, Robusta is known for its bitterness due to higher caffeine content, and it has lower sweetness and acidity compared to Arabica. Blends that combine both Arabica and Robusta have traditionally aimed to achieve a harmonious balance between aroma and flavor, integrating the desirable qualities of Arabica with the distinctive bitterness of Robusta.

 

1. In paragraphs 220-224, three strains of lactic acid bacteria (Pediococcus pentosaceus KNUT 0384, Lacticaseibacillus paracasei CJNU 1840, Lactiplantibacillus plantarum CJNU 0441) were selected for the fermentation of the coffee extract. The manuscript does not elaborate on why these specific strains were chosen, nor does it discuss whether they possess known characteristics related to coffee fermentation; it merely states that "approximately 450 strains were tested" and these three showed strong antimicrobial activity.

• We tested 450 strains in coffee extract. We made coffee extract broth and agar plates and all these strains were grown on these media. Only those strains were selected for future study which grew on all concentrations of coffee extract from 5 brix,10 brix and 20 brix. As you know, coffee extract shows very strong antimicrobial activity and lactic acid bacteria are rarely survived in the harsh environment. We shortly mentioned about it in the manuscript (line 118, line 126-127, line 245-248)

 

1. The manuscript mentions an increase in the antioxidant and antimicrobial activities of the fermented coffee extract, but it does not provide direct comparative data with the non-fermented coffee extract.

• We have mentioned the comparative data with negative control (non-fermented coffee extract). In the figures, control or BV 20brix are the negative control.

Reviewer's comments:

1. It is recommended that the authors provide more background information on the selected strains of lactic acid bacteria and why they are suitable for coffee fermentation

• As the role of LAB is crucial in fermentation process, we analyzed different strain (n= 450) and only those strains were selected for coffee fermentation which survived and shown growth in different concentrations of coffee extract.

1. Control data for the non-fermented coffee extract should be provided to more accurately assess the impact of the fermentation process.

• As mentioned above we compared data for fermented coffee extracts with non-fermented coffee extract as a control.

1. Specific P-values should be provided, and a discussion of whether the data meets the prerequisites for ANOVA analysis should be included.

• We compared data using ANOVA and Duncan’s multiple range test for post-hoc and p values are indicated in abstract and figure legends.

1. More rationale or literature support should be provided for the ratio of coffee extract used in the experiment.

• We added references for the literature support (line 83-94).

1. It is suggested that the experimental results be discussed in more depth, particularly regarding the mechanisms behind the observed decrease in caffeine content and increase in chlorogenic acid content during fermentation.

• We added explanation for possible mechanisms for caffeine degradation and increased chlorogenic acid during the fermentation with references (line 407-413, line 441-451).

1. It is recommended that the conclusion section provide more discussion on the practical implications of these findings for the potential application in the specialty coffee industry.

• We added practical implications of the fermented coffee extracts through the Conclusion section.

As a manuscript intended for publication, it is hoped that more experimental details and data will be provided. The research and thought process regarding coffee should be more in-depth. After all, using a coffee extract produced by a specific company for the experiment makes it difficult to convince readers that this study has reference and representative significance.

• Thanks for your valuable comments and we sincerely understand your concerns. So we added several references to rationalize why we used the combination of coffee species (50% Arabica + 50% Robusta, which was also recommended by Nestle Korea Co.) for the experiment. In this study we focused on selection of LAB strains which can survive in such harsh coffee extract environment and found improve functionality of fermented coffee extracts. Please understand it. Thanks.

Author Response File: Author Response.docx