Encapsulation of Extract from Tomato Pomace Applicable as Natural Colorant and Antioxidant in Low-Nitrite Sausage
Round 1
Reviewer 1 Report
Comments and Suggestions for Authors
General Commets
The manuscript addresses a relevant and timely research problem: the valorization of tomato pomace (an abundant agro-industrial by-product) through encapsulation techniques and its potential application as a natural colorant and antioxidant in meat products. The study combines food waste utilization with health-oriented meat processing, which aligns with current trends in sustainable food technology. However, despite its potential, the manuscript presents several scientific and methodological shortcomings that reduce its suitability for immediate acceptance in a high-quality journal.
- The concept of using tomato pomace extract (TPE) and its encapsulation with maltodextrin or gum Arabic has already been widely explored in food science. Several previous studies, cited in the manuscript itself, have tested similar encapsulation approaches and application in meat products. Authors should strengthen the novelty claim by clearly articulating what new knowledge their work provides compared to prior studies.
- The study does not clearly highlight its unique contribution beyond confirming existing findings. For instance, the claim that encapsulated tomato pomace improves color stability and antioxidant activity in sausages is not substantially novel. Providing better illustrations is strongly recommended.
- The abstract is too general and does not present specific quantitative findings (e.g., exact improvement in color or TBARS reduction).
- The justification for comparing only maltodextrin (MD) and gum Arabic (GA) is weak. No explanation is provided as to why these two encapsulants were chosen over others with known efficiency (e.g., modified starches, proteins, or biopolymer blends).
- The rationale for selecting only one concentration of ETPE (1%) for sausage formulation is not adequately supported by preliminary data or references.
- The microwave-assisted ethanol extraction method lacks optimization details. Only one extraction condition (180 W for 90 s) was tested, with no comparative evaluation. This limits reproducibility and raises concerns about extraction efficiency.
- The study tested only one core-to-wall ratio (1:10) and one total solid content (30%). Broader optimization (different ratios, feed solids, inlet/outlet temperatures) is necessary for strong conclusions.
- Most of the methods mentioned in the manuscript without any references!!!!!
- The study relies mainly on t-tests with very small sample sizes (n=2 for encapsulation tests, n=3–5 for sausage evaluation). This weakens the robustness of statistical inference. No ANOVA or post-hoc tests were applied to account for multiple comparisons.
- Some findings are over-interpreted. For instance, the improvement in microbial stability is modest (only ~1 log reduction after storage), yet the discussion strongly emphasizes ETPE as an antimicrobial agent.
- The discussion on color stability and antioxidant effects is largely repetitive of previous literature, with limited mechanistic insights specific to the present study.
- Data presentation (tables/figures) is at times insufficient: for example, standard deviations are small despite low replication, suggesting possible underestimation of variability.
- The manuscript is excessively descriptive in parts (e.g., introduction and discussion repeat known facts about nitrite toxicity and carotenoid instability) without integrating them into a concise argument.
- Challenges and future work should be offered
- Some methodological details are not fully clear (e.g., exact sausage formulation: in one place "pork sausage" is mentioned, elsewhere "chicken breast" is used). This inconsistency raises concerns about accuracy.
- English language requires significant polishing for fluency and scientific precision.
- References are somewhat outdated in parts, with overreliance on older spray-drying studies. More recent literature on encapsulation technologies (e.g., nanocarriers, protein-based encapsulants) could strengthen the background.
- Units and abbreviations are inconsistently reported (e.g., "mg malondialdehyde/kg" vs. "mg MDA/kg"; "ppm" vs. "mg/kg").
- Figures (e.g., TBARS and color stability graphs) lack proper statistical markers (error bars, significance indicators).
Author Response
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Response to Reviewer 1 Comments Manuscript ID macromol-3837949 “Encapsulation of extract from tomato pomace for applicable as natural colorant and antioxidant in low-nitrite sausage”
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1. Summary |
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Thank you very much for taking the time to review this manuscript. Please find the detailed responses below and the corresponding revisions/corrections highlighted in green background in the re-submitted files.
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2. Questions for General Evaluation |
Reviewer’s Evaluation |
Response and Revisions |
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Does the introduction provide sufficient background and include all relevant references? |
Must be improved |
This has been improved
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Are all the cited references relevant to the research? |
Must be improved |
This has been improved |
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Is the research design appropriate? |
Can be improved |
This has been improved |
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Are the methods adequately described? |
Must be improved |
This has been improved |
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Are the results clearly presented? |
Must be improved |
This has been improved |
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Are the conclusions supported by the results? |
Can be improved |
This has been improved |
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3. Point-by-point response to Comments and Suggestions for Authors |
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Comments 1: The manuscript addresses a relevant and timely research problem: the valorization of tomato pomace (an abundant agro-industrial by-product) through encapsulation techniques and its potential application as a natural colorant and antioxidant in meat products. The study combines food waste utilization with health-oriented meat processing, which aligns with current trends in sustainable food technology. However, despite its potential, the manuscript presents several scientific and methodological shortcomings that reduce its suitability for immediate acceptance in a high-quality journal. |
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Response 1: We sincerely appreciate you bringing this important point to our attention, with which we fully concur. The manuscript has been revised accordingly to incorporate this valuable feedback. To facilitate your review, all modifications pertaining to this comment are clearly identified with a green background within the text.
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· Comments 2: The concept of using tomato pomace extract (TPE) and its encapsulation with maltodextrin or gum Arabic has already been widely explored in food science. Several previous studies, cited in the manuscript itself, have tested similar encapsulation approaches and application in meat products. Authors should strengthen the novelty claim by clearly articulating what new knowledge their work provides compared to prior studies.
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Response 2: We do agree. Indeed, previous research has established methods for TP extraction and encapsulation (e.g., using MD or GA), with some preliminary applications in meat products. However, a significant gap exists in comprehensively integrating these advancements into a single study that leverages agricultural waste as a stable ingredient to enhance health-oriented sausage. This study is specifically designed to address this unfulfilled need, thereby establishing its novelty and paving the way for future innovations. This kind of statement has been added in the end of introduction part.
Comments 3: The study does not clearly highlight its unique contribution beyond confirming existing findings. For instance, the claim that encapsulated tomato pomace improves color stability and antioxidant activity in sausages is not substantially novel. Providing better illustrations is strongly recommended. Response 3: Although confirming existing findings are the major of this study, our study uniquely addresses a critical gap by coherently integrating the application of encapsulated TP extract. This comprehensive approach will provide invaluable supporting data, fostering the sustainable development of health-oriented food products through agricultural waste valorization. This kind of illustration is provided in the revised MS.
Comments 4: The abstract is too general and does not present specific quantitative findings (e.g., exact improvement in color or TBARS reduction). Response 4: Modification of abstract to present the specific finding has been done in the revised MS.
· Comments 5: The justification for comparing only maltodextrin (MD) and gum Arabic (GA) is weak. No explanation is provided as to why these two encapsulants were chosen over others with known efficiency (e.g., modified starches, proteins, or biopolymer blends). Response 5: We do agree and have revised the manuscript accordingly. Due to their less hygroscopic properties, these were chosen despite the well-known and suitable for encapsulating essential oil. Moreover, the polysaccharide-based wall materials are more cost effective rather than protein-based materials. These are kind of selection criterion for this study. This justification has been added in the introduction.
· Comments 6: The rationale for selecting only one concentration of ETPE (1%) for sausage formulation is not adequately supported by preliminary data or references. Response 6: Actually, the preliminary study has been done since the chicken model and found out that addition of encapsulated powder over 1% affected the technological and textural properties. Significant reduction of hardness and gel strength were observed along with an increase expressible moisture content. Therefore, addition of this powder at 1.0 % was chosen and this point has been discussed in the revised MS although the data is not presented.
· Comments 7: The microwave-assisted ethanol extraction method lacks optimization details. Only one extraction condition (180 W for 90 s) was tested, with no comparative evaluation. This limits reproducibility and raises concerns about extraction efficiency. Response 7: The extraction reproducibility and efficiency were mentioned previously in the cited reference, although it is not the major point focusing in our study. Our study was further illustrated the potential application in reduced nitrite sausage.
· Comments 8: The study tested only one core-to-wall ratio (1:10) and one total solid content (30%). Broader optimization (different ratios, feed solids, inlet/outlet temperatures) is necessary for strong conclusions. Response 8: Exactly, we do agree with this comment. Including all factors affecting the properties of encapsulated powders e.g. wall-to-core ratio, total solid, feed speed, inlet out let temperature etc. should be counted during optimization for encapsulation. However, our study is not focus exactly on the optimization of encapsulation. It is focus on how to encapsulate the extract using well know wall material based on the reported condition. In order to make sure, variation of some factor was tested e.g. inlet temperature and wall material type.
· Comments 9: Most of the methods mentioned in the manuscript without any references!!!!! Response 9: The references for each method have been added in the revised version.
· Comments 10: The study relies mainly on t-tests with very small sample sizes (n=2 for encapsulation tests, n=3–5 for sausage evaluation). This weakens the robustness of statistical inference. No ANOVA or post-hoc tests were applied to account for multiple comparisons. Response 10: The statistical analysis section was modified to be ANOVA and pos hoc different. Actually, number of n is 4 for encapsulation. In addition, the data for sausage evaluation were from 2 experiments with 3-5 measurements per each. This replication would be reliable enough for compare the responses from each attribute. The corrections of this point were included in the revised manuscript.
· Comments 11: Some findings are over-interpreted. For instance, the improvement in microbial stability is modest (only ~1 log reduction after storage), yet the discussion strongly emphasizes ETPE as an antimicrobial agent. Response 11: Discussion and interpretation are adjusted based on the supported data. The modified statements are listed in the green background.
· Comments 12: The discussion on color stability and antioxidant effects is largely repetitive of previous literature, with limited mechanistic insights specific to the present study.
Response 12: Thank you and we do agree. More discussion regarding mechanism were included in the revised MS.
· Comments 13: Data presentation (tables/figures) is at times insufficient: for example, standard deviations are small despite low replication, suggesting possible underestimation of variability. Response 13: Data presentation in the figure has been modified for more readable and the real replication are corrected.
· Comments 14: The manuscript is excessively descriptive in parts (e.g., introduction and discussion repeat known facts about nitrite toxicity and carotenoid instability) without integrating them into a concise argument. Response 14: The descriptive introduction has been modified for more concise and informative with the scientific argument.
· Comments 15: Challenges and future work should be offered Response 15: The challenge for future work has been discussed at the end of discussion.
· Comments 16: Some methodological details are not fully clear (e.g., exact sausage formulation: in one place "pork sausage" is mentioned, elsewhere "chicken breast" is used). This inconsistency raises concerns about accuracy. Response 16: All methodologies have been checked and corrected to be sausage from pork not chicken breast. The corrected points have been indicated in the revised MS.
· Comments 17: English language requires significant polishing for fluency and scientific precision. Response 17: Thank you and we do agree. Polishing English will be done after all comments were responded/corrected accordingly.
· Comments 18: References are somewhat outdated in parts, with overreliance on older spray-drying studies. More recent literature on encapsulation technologies (e.g., nanocarriers, protein-based encapsulants) could strengthen the background. Response 18: The references have been up dated in the revised MS.
· Comments 19: Units and abbreviations are inconsistently reported (e.g., "mg malondialdehyde/kg" vs. "mg MDA/kg"; "ppm" vs. "mg/kg"). Response 19: The units have been checked consistency.
· Comments 20: Figures (e.g., TBARS and color stability graphs) lack proper statistical markers (error bars, significance indicators). Response 20: The edited figures are replaced for more proper in the revised MS.
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4. Response to Comments on the Quality of English Language |
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Point 1: The English could be improved to more clearly express the research. |
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Response 1: Thank you and the polishing revised manuscript by English proving will be done in the next step after revision the content according to your comments. |
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5. Quality of Figures and Tables |
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Point 1: Figures and tables can be improved. Response 1: All figures and tables have been improved accordingly |
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Author Response File: 
Author Response.docx
Reviewer 2 Report
Comments and Suggestions for AuthorsThe submitted manuscript entitled “Encapsulation of Extract from Tomato Pomace for Applicable as Natural Colorant and Antioxidant in Low-Nitrite Sausage” describes the preparation of an extract from tomato pomace using microwave-assisted ethanol extraction, its encapsulation with gum arabic or maltodextrin via spray drying, and the application of the resulting powder in sausages with reduced sodium nitrite. The topic is current and of interest. Given the importance of the subject and the interesting results obtained by the authors, the manuscript has publication potential after the revisions indicated below are implemented. A detailed assessment follows.
- To begin with, the literature is partly outdated, and only a few citations are from 2023–2025. It would be advisable to add the latest publications on microencapsulation of lycopene and nitrite reduction in meat.
- The objective is presented only at the end of the Introduction (lines 101–104) and is formulated very generally. I recommend revising it to: “The aim of the study was to compare gum arabic and maltodextrin as wall materials for encapsulating tomato pomace extract and to assess the effects of the resulting powders on the color, oxidative properties, and microbiological characteristics of sausages with reduced nitrite content.”
- A period is missing at the end of the sentence in line 143.
- The statistical analysis relies solely on the t-test, which is insufficient for multiple groups; ANOVA with an appropriate post hoc test should be applied.
- The results are presented mainly in tables, but the text largely repeats tabled data rather than interpreting them. There is no illustration of capsule morphology (e.g., SEM micrographs), which hampers evaluation of microencapsulation effectiveness. In many places, numerical values are not provided when describing trends (e.g., “high redness levels maintained over two weeks” without a* values). The discussion of technological properties of the sausages is superficial-there is no reference to mechanisms (e.g., lycopene–myoglobin interactions).
- In line 11, the sentence “Maltodextrin was found to be the more suitable encapsulating agent” is too general-selection criteria should be added, e.g., “based on its higher radical scavenging activity and lower moisture content.”
- In line 12, “A drying temperature of 160°C was determined to be optimal…” does not explain the basis-please add that optimality was evaluated by lycopene content and radical-scavenging capacity (with numbers).
- In line 56, “Spray drying is a promising technique for transforming a TP extract into a dried powder by offering a stable powdered product” contains a repetition of “powder”-shorten to “into a stable dried product.”
- In lines 66–67, “However, encapsulation of TP extract with maltodextrin and gum Arabic have not been comparative investigated” contains a grammatical error-correct to “has not been comparatively investigated.”
- In lines 95–97, the sentence “Addition of TP extract could be an alternative…”-I propose: “Addition of encapsulated TP extract (ETPE) could be…”
- In line 132, the sentence “was evaluated using was measured” contains a duplicate word-correct to “was measured.”
- In line 160, “The model sausage … was prepared according to our previous report [11]” is insufficient-this article should provide the full formulation (percent composition of ingredients) in a table.
- In lines 216–219, the phrase “confidential level (P<0.05) … t-test analysis” is incorrect- it should read “confidence level (P<0.05)… one-way ANOVA with Tukey’s test was applied.”
- In line 268, the sentence “The high redness levels maintained over two weeks indicated that this encapsulation technology is an effective way…” describes a trend without data - please insert a* values at 0 and 2 weeks for ETPE and control samples.
Author Response
Manuscript ID-macromol-3837949 “Encapsulation of Extract from Tomato Pomace for Applicable as Natural Colorant and Antioxidant in Low-Nitrite Sausage”
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Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsThe revised manuscript is a significant improvement, and the clarifications and additional data you've provided have substantially strengthened the paper.
Reviewer 2 Report
Comments and Suggestions for AuthorsMS can be accepted
