Cultivating Value from Waste: Creating Novel Food, Feed, and Industrial Applications from Bambara Groundnut By-Products

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

 The manuscript focuses on the Bambara groundnut (BGN), a vital but underutilized legume, and systematically explores the valorization potential of its processing by-products (e.g., husks, shells, haulms). The authors have provided an exhaustive overview of the pathways to convert BGN waste into high-value products across multiple sectors, including food, feed, bioenergy, biomaterials, and environmental applications. This is complemented by a thorough analysis of the economic feasibility, market potential, challenges, and future opportunities. The following are minor suggestions aimed at making an excellent review even better.
1. A Flowchart could be designed to visually represent the BGN processing chain, showing the generation of different by-products and their subsequent conversion pathways into specific value-added products.

2.A Summary Figure could graphically present the multi-faceted benefits (e.g., economic, environmental, social) of BGN by-product valorization. This could be a central concept ("Bambara Groundnut By-product Valorization") with radiating branches showing outcomes like "New Revenue Streams," "Reduced GHG Emissions," "Improved Soil Fertility," and "Job Creation."

 3.The review is well-referenced. A minor point for consideration is that some key market data (e.g., market projections for biofuels and biofertilizers ) cite reports for 2025. Given the pace of academic publishing, it might be beneficial for the authors to perform a final check for any more recent industry reports or market data before final submission to ensure the information is as current as possible. This is a minor suggestion and not a requirement.

4. The review is well-referenced. A minor point for consideration is that some key market data (e.g., market projections for biofuels and biofertilizers ) cite reports for 2025. Given the pace of academic publishing, it might be beneficial for the authors to perform a final check for any more recent industry reports or market data before final submission to ensure the information is as current as possible. This is a minor suggestion and not a requirement.

 

Author Response

Comments 1: A Flowchart could be designed to visually represent the BGN processing chain, showing the generation of different by-products and their subsequent conversion pathways into specific value-added products.

 

Response 1:  This has been done (Fig.1)

 

Comments 2: .A Summary Figure could graphically present the multi-faceted benefits (e.g., economic, environmental, social) of BGN by-product valorization. This could be a central concept ("Bambara Groundnut By-product Valorization") with radiating branches showing outcomes like "New Revenue Streams," "Reduced GHG Emissions," "Improved Soil Fertility," and "Job Creation."

 

Response 2:  I am sure that has been addressed in Figure 1 as suggested earlier.

 

Comments 3:.The review is well-referenced. A minor point for consideration is that some key market data (e.g., market projections for biofuels and biofertilizers ) cite reports for 2025. Given the pace of academic publishing, it might be beneficial for the authors to perform a final check for any more recent industry reports or market data before final submission to ensure the information is as current as possible. This is a minor suggestion and not a requirement.

 

Response 3:  We just did that and it looks like what we currently have is what is verifiable. Other information obtained, although not entirely or significantly different from what we, are not published.

 

Comments 4. The review is well-referenced. A minor point for consideration is that some key market data (e.g., market projections for biofuels and biofertilizers ) cite reports for 2025. Given the pace of academic publishing, it might be beneficial for the authors to perform a final check for any more recent industry reports or market data before final submission to ensure the information is as current as possible. This is a minor suggestion and not a requirement.

 

Response 4: Same as above

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

This is an interesting, well-written and updated manuscript, highlighting alternative applications for Bambara groundnut by-products, aligned with the concept of sustainable development and the principles of the circular economy, which promote waste reduction and efficient resource use through recycling strategies.

I consider that the manuscript would be reconsider after a minor revision considering the following aspects:

• Some general concerns:

1. Are there reported differences between the varieties of Bambara groundnut (Vigna subterranea) with respect to the nutritional composition and bioactive profiles?
2. If information is available, it would be interesting to include in the article a comparative table with the composition of the different by-products obtained from Bambara groundnut. Moreover, a composite figure with images of the plant and the by-products would be illustrative.
3. Based on the review made, I suggest including a diagram summarizing a general technological proposal for the valorization of Bambara groundnut. by-products.

• Other suggestions:

1. In the title of section 2.3 (lines 154-155), the term "probiotic" should be replaced by "prebiotic" because it refers to components of the by-products, not to the probiotic microorganism. In lines 166-167, the term is used correctly because it refers to fermentation of BGN using lactic acid bacteria to produces a probiotic drink.
2. Line 154: The title of the section suggests the discussion of antioxidants, but no reference is made to the classes of antioxidant compounds present in BGN.
3. Lines 164-165 “Also, extracts from BGN grains have demonstrated antimicrobial properties against bacteria and fungi…”. Give examples of susceptible microorganisms.
4. Line 177, replace “vital amino acids” by “essential amino acids”.
5. In addition to the excellent amino acid profile of BGN protein, are there studies related to its digestibility?For example, the Protein Digestibility Corrected Amino Acid Score (PDCAAS).
6. Line 189: Plant fats do not contain cholesterol.
7. With respect to the nutritional profile of BGN, particularly micronutrients, is there information about vitamin content, in addition to what is reported about minerals?

 

Author Response

Comments 1. Are there reported differences between the varieties of Bambara groundnut (Vigna subterranea) with respect to the nutritional composition and bioactive profiles?

 

Response 1:  While the paper acknowledges the rich genetic diversity of Bambara groundnut and notes that diverse genetic accessions can influence characteristics like oil extraction for biofuel production—even identifying a specific genotype (BGS-G1) suitable for pyrolysis—it does not explicitly detail reported differences in the general nutritional composition or comprehensive bioactive profiles among different varieties or genotypes of Bambara groundnut.

Comments 2: If information is available, it would be interesting to include in the article a comparative table with the composition of the different by-products obtained from Bambara groundnut. Moreover, a composite figure with images of the plant and the by-products would be illustrative.

 

Response 2:  A brief Table has been inserted

Comments 3. Based on the review made, I suggest including a diagram summarizing a general technological proposal for the valorization of Bambara groundnut. by-products.

 

Response 3: Something like that has emerged already in Fig. 1 and as suggested by one of the reviewers

Comments 4:. In the title of section 2.3 (lines 154-155), the term "probiotic" should be replaced by "prebiotic" because it refers to components of the by-products, not to the probiotic microorganism. In lines 166-167, the term is used correctly because it refers to fermentation of BGN using lactic acid bacteria to produces a probiotic drink.

 

Response 4:  This is well noted

Comments 6:. Line 154: The title of the section suggests the discussion of antioxidants, but no reference is made to the classes of antioxidant compounds present in BGN.

 

Responses 6:  Actually, in an attempt to be brief, we did mention at least, in a sentence or two, all contents mentioned in the title (line 154-155). Antioxidants were mentioned from 156-159. However, the paragraph has been remodified.

Comments 7:. Lines 164-165 “Also, extracts from BGN grains have demonstrated antimicrobial properties against bacteria and fungi…”. Give examples of susceptible microorganisms.

 

Response 7: Done

Comments 8: Line 177, replace “vital amino acids” by “essential amino acids”.

 

Regular 8: Done

Comments 9: In addition to the excellent amino acid profile of BGN protein, are there studies related to its digestibility?For example, the Protein Digestibility Corrected Amino Acid Score (PDCAAS).

 

Response 9: True, the paper indicates that while it doesn't explicitly mention Protein Digestibility Corrected Amino Acid Score (PDCAAS) for Bambara groundnut (BGN) protein, it does address digestibility by discussing how anti-nutritional factors like tannins and trypsin inhibitors can impair protein utilization. Crucially, it highlights that common processing methods (boiling, roasting, sprouting, soaking) can significantly reduce these factors, thereby increasing the bioavailability and utilization of BGN nutrients, implying improved protein digestibility.

Comments 10:. Line 189: Plant fats do not contain cholesterol.

 

Response 10: The word “and no cholesterol” has been removed

Comments 11. With respect to the nutritional profile of BGN, particularly micronutrients, is there information about vitamin content, in addition to what is reported about minerals?

 

Comment 11: It has been included

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

Dear Authors,

Thank you for the opportunity to read this interesting article. However, I have a few comments I feel are necessary to fit into your article before publication.

The most critical point is that in your article, there are no tables with data, graphs, or statistical analysis performed. Even though this is a literature review, it is necessary in scientific papers to include data that can be statistically analyzed and then discussed. In my opinion, without the inclusion of such summaries combined with a discussion, the article cannot be published.

I include some additional comments below connected with the main comment:

• Please clearly indicate in the Introduction section what the primary purpose of the work is.
• A methodology section is missing, which describes how and with what techniques the literature review was conducted, e.g., PRISMA. What databases were searched? What were the inclusion/exclusion criteria for the papers selected for the bibliography? This would allow readers of the article to visualize the measure of achievement of the authors' goal in the paper.
• The text lacks a clear scientific discussion due to a lack of data collation and analysis. Admittedly, the citations are well chosen, but the work has the character of a report.

Comments on specific parts of the text:

• Line 77 - Please elaborate on what “minimal inputs” means.
• Line 85 - I suggest adding statistics on BGN cultivation in Nigeria.
• Line 156 - What does it mean that BGN is rich in flavonoids, saponins, and alkaloids? Please provide content ranges and relate this to other related nuts for comparison.
• Line 279-281 - Since ROI is so significant, it is worth noting the expected rate of return and referring to the economic literature as to whether an investment in BGN can be considered profitable.
• Line 402 - Since there is so little fat and so much phosphorus in BGN, does it make sense to produce biofuel from it?
• Line 424 - Likewise for animal feed. Feed production is only justified if proteins are used as the main component of feed. This should be better specified.
• Line 521 - Including social risks in the risk analysis seems reasonable. What if consumers do not accept derivative products? Admittedly, financial risks were mentioned, but from the point of view of production. What if, for example, biofuel is too expensive and consumers do not want to use it?
• Line 650 - The conclusions section should be rewritten after considering the comments.
• Line 682 - The 84 literature items in the bibliography for the review seem to be a minimal amount of analyzed literature. However, this may be due to the specificity of the subject matter. It would be worthwhile to fit the literature statistics from large databases of scientific articles on the number of articles corresponding to the keywords in the methods section, which I mentioned adding, to explain to readers why this is such a niche topic. If multiple articles about BGN exist in the databases, the article should be strengthened with additional papers. In addition, some of the items are older than 20 years. Why these are relevant items for this article should be explained.

Author Response

Comments 1: The most critical point is that in your article, there are no tables with data, graphs, or statistical analysis performed. Even though this is a literature review, it is necessary in scientific papers to include data that can be statistically analyzed and then discussed. In my opinion, without the inclusion of such summaries combined with a discussion, the article cannot be published.

 

 Response 1: We have made effort to address this concern by including a Table and a Figure

Comments 2: I include some additional comments below connected with the main comment:

 

 Response 2: Some information has been affixed to the end of the INTRODUCTION

Comments 3: Please clearly indicate in the Introduction section what the primary purpose of the work is.

 

 Response 3: Included in the work, towards the end of the Introduction after line 126

Comments 4: A methodology section is missing, which describes how and with what techniques the literature review was conducted, e.g., PRISMA. What databases were searched? What were the inclusion/exclusion criteria for the papers selected for the bibliography? This would allow readers of the article to visualize the measure of achievement of the authors' goal in the paper.

Comments 5: The text lacks a clear scientific discussion due to a lack of data collation and analysis. Admittedly, the citations are well chosen, but the work has the character of a report.

 

 Response 5: Thanks for the observation. However, since a suggestion on a better way to improve the report in the suggested direction wasn’t provided, and since we couldn’t come up with any at the moment, we allowed it be.

Comments 6:  Line 77 - Please elaborate on what “minimal inputs” means.

 

 Response 6: The "minimal inputs" required for Bambara groundnut (BGN) cultivation refer to its ability to thrive efficiently without the need for significant external resources, making it an ideal crop for sustainable farming systems, particularly for resource-poor farmers. This has been so-reflected

Comments 7:  Line 85 - I suggest adding statistics on BGN cultivation in Nigeria.

 

 Response 7: Done

Comments 8:  Line 156 - What does it mean that BGN is rich in flavonoids, saponins, and alkaloids? Please provide content ranges and relate this to other related nuts for comparison.

 

 Response 8: With respect to comparison to other related nuts, the paper does not provide direct quantitative comparisons of the specific content of flavonoids, saponins, or alkaloids between Bambara groundnut and other related nuts. Its comparative analyses are typically focused on macronutrient profiles or specific anti-nutritional factors rather than these precise bioactive compound levels across different nut types.

Comments 9: Line 279-281 - Since ROI is so significant, it is worth noting the expected rate of return and referring to the economic literature as to whether an investment in BGN can be considered profitable.

 

 Response 9: This review highlights the crucial role of Return on Investment (ROI) in sustaining Bambara groundnut production, noting that higher profits are expected when BGN waste substitutes costly alternatives. While it explores market growth potential for BGN-derived products and factors affecting profitability, the review doesn't provide specific ROI percentages or cite economic literature with precise ROI figures; instead we have decided to focus on the broader economic benefits of waste valorization, especially for privity, and so we stay focused. Majorly, that the point has been passed. I hope our argument suffices.

Comments 10:  Line 402 - Since there is so little fat and so much phosphorus in BGN, does it make sense to produce biofuel from it?

 

 Response 10: This review suggests that producing biofuel from Bambara groundnut (BGN) is feasible, but only from the shell residues, not the whole nut. The shells' lignocellulosic composition makes them suitable for thermochemical conversion, producing bio-oil. While the whole nut's low fat content (5.2-6.5%) makes it less efficient for oil-based biofuel production, the authors argue therefore that the phosphorus content is not a determining factor in biofuel conversion efficiency. The study proposes utilizing BGN shell residues for biofuel production due to their lignocellulosic nature.

Comments 11: Line 424 - Likewise for animal feed. Feed production is only justified if proteins are used as the main component of feed. This should be better specified.

 

 Response 11: Using Bambara groundnut (BGN) by-products, especially offal, as animal feed is justified due to their high protein content (20.34-22.65%). We have now included that in the new Table attached

Comments 12:  Line 521 - Including social risks in the risk analysis seems reasonable. What if consumers do not accept derivative products? Admittedly, financial risks were mentioned, but from the point of view of production. What if, for example, biofuel is too expensive and consumers do not want to use it?

 

 Response 12: This work does address social risks, specifically the potential consumer resistance to derivative products due to lack of standardization and regulations. Additionally, it mentions the challenge of lack of awareness and insufficient support from consumers and policymakers. However, it does not specifically analyze the risk of derivative products being too expensive for consumers to adopt, focusing instead on financial risks from the producer's perspective.

Comments 13:   Line 650 - The conclusions section should be rewritten after considering the comments.

 

 Response 13: Done

Comments 14:   Line 682 - The 84 literature items in the bibliography for the review seem to be a minimal amount of analyzed literature. However, this may be due to the specificity of the subject matter. It would be worthwhile to fit the literature statistics from large databases of scientific articles on the number of articles corresponding to the keywords in the methods section, which I mentioned adding, to explain to readers why this is such a niche topic. If multiple articles about BGN exist in the databases, the article should be strengthened with additional papers. In addition, some of the items are older than 20 years. Why these are relevant items for this article should be explained.

 

 Response 14: The timeline had to be expanded and kept open when we realized that in total we could retrieve very little data within the first 10years where our initial search started. We even had to stretch till 15 years. So we decided to stretch the timeframe further to access more information.

Author Response File: Author Response.docx

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

In my opinion, the article looks much better. Two minor comments:

To Response 10: This should resound more in the text. Maybe combine with a short diagram?

To Response 12: However, it cannot be denied that this is an important issue. Therefore, in my opinion, it is worth mentioning.

Author Response

Comments 1: To Response 10: This should resound more in the text. Maybe combine with a short diagram?

Response 1: I think the advise is good. This has been included in the text in line 501 – 507.

 

Comment 2: To Response 12: However, it cannot be denied that this is an important issue. Therefore, in my opinion, it is worth mentioning.

Response 2: This has been included in line 614 - 620