Plant Extracts as Natural Inhibitors of Non-Enzymatic Browning: A Case of Fruits and Fruit-Based Products
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe manuscript by Vhangani and Van Wyk presents a review on the role of plant extracts in inhibiting non-enzymatic browning reactions during the processing and storage of fruit and fruit-based products. The topic is relevant and well suited for AppliedChem.
Comments and Suggestions:
1) "an hermetic" should be changed to "a hermetic."
2) The sentence "...are those mentioned in[5] known[6] for producing quality canned products" should be fixed, e.g. “…such as Langeberg & Ashton Foods, Rhodes Food Group, Del Monte Foods South Africa, Boland Pulp, and Summerpride, which are known for producing quality canned products [5,6]".
3) When describing the Agricultural Product Standards Act 119 of 1990, please specify that this corresponds to a South African regulation.
4) The statement "...it should be stressed that thermal processing is not always required to achieve complete sterility of food" should be clarified. Isn’t thermal processing obligatory to achieve commercial sterility?
5) Please indicate whether non-English sources were included in the literature search. Also, replace "~100 selected articles" (informal) with "approximately 100 selected articles".
6) It is strongly recommended that the authors update the literature search to include publications from 2024–2025, as food chemistry is a rapidly developing field. This is a major weakness of the current manuscript.
7) Please define the term "white fruits".
8) The figures (incl. text within schemes) are very pixelated, and the drawing style is inconsistent, for example, compare the structure of glucosone with other compounds in Figure 2.3. If possible, the authors should redraw the schemes using professional chemical drawing software to ensure consistency.
9) An Abbreviations section should be added.
Author Response
The manuscript by Vhangani and Van Wyk presents a review on the role of plant extracts in inhibiting non-enzymatic browning reactions during the processing and storage of fruit and fruit-based products. The topic is relevant and well suited for AppliedChem.
Thank you for taking the time to review our manuscript and for providing constructive comments that helped us identify and address key issues. Please find below our detailed responses to each question and query. One of the reviewers noted the absence of line numbers, which made the review process challenging. We have therefore added line numbers to the revised manuscript and will refer to these line numbers when addressing each specific comment.
Comments and Suggestions:
1) "an hermetic" should be changed to "a hermetic."
2) The sentence "...are those mentioned in [5] known [6] for producing quality canned products" should be fixed, e.g. “…such as Langeberg & Ashton Foods, Rhodes Food Group, Del Monte Foods South Africa, Boland Pulp, and Summerpride, which are known for producing quality canned products [5,6]".
3) When describing the Agricultural Product Standards Act 119 of 1990, please specify that this corresponds to a South African regulation.
4) The statement "...it should be stressed that thermal processing is not always required to achieve complete sterility of food" should be clarified. Isn’t thermal processing obligatory to achieve commercial sterility?
One of the major comments highlighted that the discussion on canning in the introduction did not align with the scope of the current study. Upon revisiting the manuscript, we agreed that this section was more relevant to the broader PhD project rather than the current manuscript. Consequently, we have removed all content specifically related to canning, including references to the canning industry in South Africa. Therefore, reviewer comments 1–4 are no longer applicable in the revised manuscript.
5) Please indicate whether non-English sources were included in the literature search. Also, replace "~100 selected articles" (informal) with "approximately 100 selected articles".
We have made corrections as recommended, please see line 77 and 83.
6) It is strongly recommended that the authors update the literature search to include publications from 2024–2025, as food chemistry is a rapidly developing field. This is a major weakness of the current manuscript.
We managed to include a few 2024 articles regarding NEB, however, we could not find any work produced in 2025 that could fit the scope of this paper.
7) Please define the term "white fruits".
The correct term is white-fleshed fruit defined as a fruit with a white, or creamy-white, edible pulp on the inside. We have corrected this in line 110.
8) The figures (incl. text within schemes) are very pixelated, and the drawing style is inconsistent, for example, compare the structure of glucosone with other compounds in Figure 2.3. If possible, the authors should redraw the schemes using professional chemical drawing software to ensure consistency.
Unfortunately, we do not have access to software such as Chem 4D Draw. As a result, we have removed the figures from the manuscript. In addition, we encountered challenges in obtaining copyright permissions from the publishers and therefore decided to remove all figures altogether.
9) An Abbreviations section should be added.
An abbreviations section was added as recommended, see line 692.
Reviewer 2 Report
Comments and Suggestions for AuthorsThe authors discussed the role of plant extracts in inhibiting non-enzymatic browning (NEB) reactions during the processing and storage of fruit and fruit-based products. The review provides details of the chemical reactions occurring during canning, with particular emphasis on the pathways of three major types of NEB reactions. It also discusses approaches for preventing NEB using plant extracts, highlighting the underlying inhibitory mechanisms and their limitations. Finally, the use of encapsulation is considered a potential approach to overcome the limitations associated with plant extracts.
This review is comprehensive and provides a systematic overview of the current knowledge on the use of plant extracts to inhibit non-enzymatic browning in fruit and fruit-based products.
Comments:
- All abbreviations should be defined when first introduced in the text (e.g., AA, MR, HMF, etc.). In addition, the use of abbreviations is unnecessary when a term appears only once in the manuscript. The authors are advised to check the entire manuscript for consistency in abbreviation use.
- Subsection 3.3.2. Please add the reference numbers for Pham et al. (2019), Valero (2017), Wibowo et al. (2015a), etc.
- References 16 and 29 are identical. The authors should verify all references (in the manuscript and the reference list) to ensure that there are no duplicates or errors.
- Subsection 4.1 ”Polyphenols as major bioactives in plant extracts” The wording should be refined, ‘bioactives’ should be replaced with the more accurate terms ‘bioactive compounds’ or ‘bioactive constituents”
- In subsection 4.3. Limitations of plant extracts, the authors stated: “Although these plant extracts prove to exhibit excellent anti-browning activities in vitro, the final intended application is in food processing and storage. “ It is unclear which specific plant extracts the authors are referring to in this statement. Please specify the extracts to improve clarity and add the reference.
- Further, the authors stated: “However, crude plant extracts or purified individual polyphenols thereof have been reported to affect color changes when incorporated in food or model systems. This might be influenced by either natural pigmentation, or reaction of polyphenols with food components resulting in colour augmentation. These changes are also accelerated by high temperatures employed during common food preservation methods such as drying, pasteurisation and sterilisation, leading to reduced bioactivities.” Please add references.
- It would be useful for the authors to include a Conclusion or Future Perspectives section, summarizing the main insights and suggesting possible directions for further studies.
Comments on the Quality of English LanguageThe manuscript, including the Abstract, requires English editing, as grammatical errors and inconsistent punctuation affect readability and clarity.
Author Response
REVIEWER 2
The authors discussed the role of plant extracts in inhibiting non-enzymatic browning (NEB) reactions during the processing and storage of fruit and fruit-based products. The review provides details of the chemical reactions occurring during canning, with particular emphasis on the pathways of three major types of NEB reactions. It also discusses approaches for preventing NEB using plant extracts, highlighting the underlying inhibitory mechanisms and their limitations. Finally, the use of encapsulation is considered a potential approach to overcome the limitations associated with plant extracts.
This review is comprehensive and provides a systematic overview of the current knowledge on the use of plant extracts to inhibit non-enzymatic browning in fruit and fruit-based products.
Thank you for taking the time to review our manuscript and for providing constructive comments that helped us identify and address key issues. Please find below our detailed responses to each question and query. One of the reviewers noted the absence of line numbers, which made the review process challenging. We have therefore added line numbers to the revised manuscript and will refer to these line numbers when addressing each specific comment.
Comments:
- All abbreviations should be defined when first introduced in the text (e.g., AA, MR, HMF, etc.). In addition, the use of abbreviations is unnecessary when a term appears only once in the manuscript. The authors are advised to check the entire manuscript for consistency in abbreviation use.
We thoroughly reviewed the manuscript and made the recommended adjustments. Additionally, we included a section explaining the key abbreviations used in the manuscript, as suggested by one of the reviewers. Please refer to line 692 for this addition
- Subsection 3.3.2. Please add the reference numbers for Pham et al. (2019), Valero (2017), Wibowo et al. (2015a), etc.
Citations have been corrected. See Pham et al. (2009) [40]; Valero (2017) [41]; Wibowo et al. (2015a)
- References 16 and 29 are identical. The authors should verify all references (in the manuscript and the reference list) to ensure that there are no duplicates or errors.
Corrected
- Subsection 4.1 ”Polyphenols as major bioactives in plant extracts” The wording should be refined, ‘bioactives’ should be replaced with the more accurate terms ‘bioactive compounds’ or ‘bioactive constituents”
The section in line 410 has been rephrased to “4.1. Polyphenols as major bioactive compounds in plant extracts”
- In subsection 4.3. Limitations of plant extracts, the authors stated: “Although these plant extracts prove to exhibit excellent anti-browning activities in vitro, the final intended application is in food processing and storage. “ It is unclear which specific plant extracts the authors are referring to in this statement. Please specify the extracts to improve clarity and add the reference.
The sentence has been rephrased: Although the above-mentioned plant extracts (4.2) prove to exhibit excellent anti-browning activities in vitro, the final intended use is application in food formulation and must withstand processing and storage conditions.
- Further, the authors stated: “However, crude plant extracts or purified individual polyphenols thereof have been reported to affect color changes when incorporated in food or model systems. This might be influenced by either natural pigmentation, or reaction of polyphenols with food components resulting in colour augmentation. These changes are also accelerated by high temperatures employed during common food preservation methods such as drying, pasteurisation and sterilisation, leading to reduced bioactivities.” Please add references.
See the citation in line 582 and 586.
It would be useful for the authors to include a Conclusion or Future Perspectives section, summarizing the main insights and suggesting possible directions for further studies. See the section on conclusion and recommendations
Reviewer 3 Report
Comments and Suggestions for Authors- A high percentage of matches (91%), how do the authors explain this?
- The second paragraph of the introduction is of an advertising nature and does not contain scientific information.
- The first sentence in the introduction is poorly formulated and does not provide a total definition of the term "canning".
- All references in the Introduction section are older than 5 years old.
- The Introduction does not reveal the title, aim and novelty of the study at all.
- The aim of the study is not clearly defined. The introduction needs to be rewritten and updated (use relevant publications). Modern studies (2024-2025) are missing.
- Define the lines numbers or use the journal template properly. It is hard to review without them.
- There are many poorly formulated phrases that are out of context. Many unfounded phrases like: "only a small amount of fruits are consumed in their raw state," "so-called white fruits," "is of vital significance," "color is the deciding factor to buy."
- Three major browning reactions or four?
- Section 3.1 partially copies Section 3.
- Section 3.1. Is the last paragraph the aim of the review? Section 3 already has an aim stated.
- What means “MR”? There is no explanation at the first mention.
- Fig. 2.1, 2.2 are fully described in the text.
- The reference sources are outdated; the review requires updating and systematization. The aim of the study must be stated in the Introduction. The title should also reflect the content of the article.
- Section 3 doesn't fit the title of the paper. Either change the title or significantly shorten the section.
- Add list of abbreviations.
- There are very few studies specifically covering the use of plant extracts for preservation. Only section 4.2 and parts of 4.1 are relevant to this topic.
- Sections 4.4 and 4.5 describe methods for encapsulation and extraction of such extracts without reference to NEB. Authors refer to only three works for 2 sections. Moreover, on the topic of the study there is only 1 reference [94] which is self-citation.
- There is no conclusion or findings.
- The manuscript requires major revision.
Author Response
A high percentage of matches (91%), how do the authors explain this?
This content originates from the literature review of a PhD thesis titled “The use of nano-encapsulated plant extracts in inhibiting non-enzymatic browning in fruit canned in juice”. From this thesis, three related papers were published in MDPI Foods, Molecules, and Applied Sciences. The full thesis is available in the CPUT repository, which explains the observed similarities
- The second paragraph of the introduction is of an advertising nature and does not contain scientific information.
Upon thorough reviewing of our manuscript, we agreed that the concept of canning was more relevant to the broader PhD project objective rather than the current manuscript. We agree that the discussion on canning in the introduction does not align with the scope of the current study. Consequently, we have removed all content specifically related to canning, including references to the canning industry in South Africa.
- All references in the Introduction section are older than 5 years old.
The PhD research spanned six years, from 2017 to 2023, and the literature review was developed during that period. Additionally, due to the nature of the study, it was essential to include some earlier foundational research on NEB, as these works remain relevant and significant to the topic- The Introduction does not reveal the title, aim and novelty of the study at all.
- The aim of the study is not clearly defined. The introduction needs to be rewritten and updated (use relevant publications). Modern studies (2024-2025) are missing.
We have removed all content related to canning and focused exclusively on NEB and mitigation strategies in fruits and fruit-based products. Please refer to the revised introduction for these updates. We managed to include a few 2024 articles regarding NEB, however, we could not find any work produced in 2025 that could fit the scope of this paper.
- Define the lines numbers or use the journal template properly. It is hard to review without them.
Apologies for not numbering the manuscript. This was an oversight form our side. The reviewer will be pleased to see that we applied line numbers to the manuscript
- There are many poorly formulated phrases that are out of context. Many unfounded phrases like: "only a small amount of fruits are consumed in their raw state," "so-called white fruits," "is of vital significance," "color is the deciding factor to buy."
The statements were rephrased for better reading and understanding. See line 100 – 110. The statement “white fruits” has been rephrased to an appropriate term “white-fleshed fruit”.
- Three major browning reactions or four?
The browning has been changed to specify the three NEB reactions only. It becomes four if enzymatic browning is included.
- Section 3.1 partially copies Section 3.
- Section 3.1. Is the last paragraph the aim of the review? Section 3 already has an aim stated.
Upon revisiting section 3 and 3.1, we fully agree with the reviewer and decided to merge the two together and have one aim.
- What means “MR”? There is no explanation at the first mention.
This is the abbreviation for the term Maillard reaction, but it has since been rectified.
- Fig. 2.1, 2.2 are fully described in the text.
One of the reviewers made comments about the quality of the figures, as well as the journal had queries regarding copyright. Unfortunately, we do not have access to software such as Chem 4D Draw. As a result, we have removed the figures from the manuscript. moreover, we encountered challenges in obtaining copyright permissions from the publishers and therefore decided to remove all figures altogether.
- The reference sources are outdated; the review requires updating and systematization. The aim of the study must be stated in the Introduction. The title should also reflect the content of the article.
We have revised the manuscript, and we hope the reviewer will now find the content more aligned with the title and overall focus of the study.
- Section 3 doesn't fit the title of the paper. Either change the title or significantly shorten the section.
Section 3 has been condensed, with all content related to canning removed to focus exclusively on the processing of fruits and fruit-based products. This revision provides a clearer link to Section 3.1, which offers a brief overview of non-enzymatic browning reactions occuring during processing.
- Add list of abbreviations.
. A list of abbreviation and their full terms has been included. See last section of the manuscript.
- There are very few studies specifically covering the use of plant extracts for preservation. Only section 4.2 and parts of 4.1 are relevant to this topic.
We included Sections 3 and 4 to provide proper context for Sections 4.1 and 4.2. We believe including these sections enhances the overall coherence and flow of the manuscript. We hope that, with these revisions, the reviewer will recognise the relevance and necessity of these additions.
- Sections 4.4 and 4.5 describe methods for encapsulation and extraction of such extracts without reference to NEB. Authors refer to only three works for 2 sections. Moreover, on the topic of the study there is only 1 reference [94] which is self-citation.
It is essential to discuss extraction and encapsulation techniques before addressing the role of encapsulation in mitigating the degradation of phenolic compounds. In Sections 4.4 and 4.5, at least five studies are presented that examine the effects of encapsulation in preventing NEB. Although several of these studies were conducted in vitro, two were in vivo. For example, Lavelli and Sri Harsha (2019) and Favre (2018, 2020) conducted experiments using model systems, while Hildago et al. (2018) investigated the effect on water biscuits. In our 2023 study, we evaluated this in canned apples.
- There is no conclusion or findings.
The section has been added into the manuscript
- The manuscript requires major revision.
Major revision has been done on the manuscript; we hope it is to the expectation of the reviewer.
.
Round 2
Reviewer 1 Report
Comments and Suggestions for Authors< !--StartFragment -->
I would like to thank the authors for addressing the points raised in the initial review. Unfortunately, following the removal of all figures and schemes from the manuscript, I can no longer recommend its acceptance. Figures, schemes, and other illustrations are crucial components of review articles, and readers rely on them. There are numerous free, high-quality programs for drawing chemical structures (e.g. ChemSketch) and copyright issues can be avoided by redrawing the figures in the authors’ own style.
< !--EndFragment -->
Author Response
Dear Reviewer 1
Thank you for your valuable feedback and for clarifying the matter regarding the use of figures and copyright. Your bold stance on our paper has to go a step further and consider ways to strengthen our paper. You alos helped us better understand how to appropriately include visual materials in our manuscript without having to pay exorbitant fees or face a possible lawsuit.
Following your advice, we have recreated all the figures and schemes using Marvin, ensuring that each one has been redrawn in our own style while maintaining scientific accuracy. We have also ensured that none of the illustrations infringe on any copyright restrictions by declaring that they were recreated. Furthermore, you helped us challenge the initial copyright matter by noting the diffrences and distinctiveness of our fiugure from that of the original authors.
Given these revisions, we kindly request that you re-look at the new figures and revoke the rejection decision on our manuscript . The inclusion of these newly recreated figures significantly enhances the clarity (better qulaity and resolution) and readability of the review, aligning with your earlier observation about their importance.
Information regarding the inclusion of Figures 1 – 4 is illustrated by sections highlighted in green throughout the manuscript.
Thank you once again for your thoughtful guidance and for taking the time to review this work.
Kind regards
Vhangani and Van Wyk
Reviewer 3 Report
Comments and Suggestions for AuthorsThe authors did a great work on revising the article and it can be published in the present form.
Author Response
Dear Reviewer 3
Thank you for reviewing our manuscript and finding it suitable for publication.
Round 3
Reviewer 1 Report
Comments and Suggestions for AuthorsI would like to thank the authors for adding the Figures and Schemes to the manuscript. One minor point: the structure on the right in Fig. 1 is 2-furoic acid, not furfural. Also, please check and fix the bond angles in some of the structures (e.g. 2,3-enegulonic acid and xylose in Fig. 2, 2,3-diketogulonic acid in Fig. 1 etc.).
Author Response
Dear Reviewer 1
We sincerely thank you for your valuable time and constructive feedback throughout the review process. We addressed and corrected the errors as indicated below:
- The structure on the right in Figure 2 has been corrected from 2-furoic acid to furfural.
- New structures were created to fix the bond angles in 2,3-diketogulonic acid and 2,3-enegulonic acid in Figure 1, as well as xylose in Figure 2.
Kind regards
