Nanofibers of Jussara Pulp: A Tool to Prevent the Loss of Thermal Stability and the Antioxidant Activity of Anthocyanins after Simulated Digestion

Round 1

Reviewer 1 Report

The authors develop a type of nanofiber composites incorporated with anthocyanins from jussara pulp using electrospinning technique. The composites maintain their antioxidant activity, and the thermal stability of anthocyanins is improved, showing protective effect over bioactive compounds. To determine the antioxidant activity and the thermal stability, the authors also evaluate the biological effects of anthocyanins from jussara pulp, polymer solution and nanofiber composites during and after in vitro digestion by quantifying the anthocyanin concentrations in each sample. The results are interesting. The presentation is clear. The paper is recommended for publication in Processes. Some minor revisions are suggested below.
1. There is no figure caption for A and B in Figure 1. Why are there so many nodes on the surface of electrospun jussara nanofibers? How to determine the average diameter to be 120 ± 80 nm? The standard deviation is very large. A similar work on electrospinning is suggested, Chin. Chem. Lett., 32, 2448 (2021).
2. In the section of “Conclusion”, there are many descriptions of others’ works, which are suggested to be simplified or put in the section of “Introduction”. What are the advantages of the work described in this paper?
3. The authors state that “Several reactions between JP and PEO can occur, mainly due to the complex matrix of the fruit that includes a considerable amount of lipids and fibers and the interactions between the other components of the fruit”. What are the reactions could be? PEO is relatively inert.
4. For the thermal stability, the authors perform experiments at two elevated temperatures. What about room temperature?
5. A similar work on composite materials via electrospinning is suggested, Chin. Chem. Lett., 32, 3372 (2021).

Author Response

We would like to thank the reviewers for their valuable comments and suggestions for our manuscript. We have modified the manuscript according to the recommendations, and the detailed, point-by-point corrections are listed below. The modifications requested were extremely important to improve our work. All sentences/words listed below are highlighted in the revised version of the manuscript.

Reviewer 1:

Comment: The authors develop a type of nanofiber composites incorporated with anthocyanins from jussara pulp using electrospinning technique. The composites maintain their antioxidant activity, and the thermal stability of anthocyanins is improved, showing protective effect over bioactive compounds. To determine the antioxidant activity and the thermal stability, the authors also evaluate the biological effects of anthocyanins from jussara pulp, polymer solution and nanofiber composites during and after in vitro digestion by quantifying the anthocyanin concentrations in each sample. The results are interesting. The presentation is clear. The paper is recommended for publication in Processes. Some minor revisions are suggested below.

1. There is no figure caption for A and B in Figure 1. Why are there so many nodes on the surface of electrospun jussara nanofibers? How to determine the average diameter to be 120 ± 80 nm? The standard deviation is very large. A similar work on electrospinning is suggested, Chin. Chem. Lett., 32, 2448 (2021).

Response: The authors appreciate the opportunity to improve the manuscript. The caption of Figure 1 was modified, and the suggested reference was added. The molecular weight and concentration of the solution used in electrospinning interfere with the stretching of the fibers during the process, and the formation of a continuous jet is important for the uniformity in the morphology of the fibers. However, the stability of the jet can be affected during the process, either with the formation of small air bubbles in the solution or even small oscillations in the applied voltage, causing the formation of beads. In addition, the molecular weight and concentration of PEO used were high and the entanglement of the polymer chains also leads to the formation of these granules.

Comment: In the section of “Conclusion”, there are many descriptions of others’ works, which are suggested to be simplified or put in the section of “Introduction”. What are the advantages of the work described in this paper?

Response: The conclusion section was rewritten as requested.

Comment: The authors state that “Several reactions between JP and PEO can occur, mainly due to the complex matrix of the fruit that includes a considerable amount of lipids and fibers and the interactions between the other components of the fruit”. What are the reactions could be? PEO is relatively inert.

Response: The phrase was corrected in the manuscript; we express ourselves imprecisely, instead of reactions we meant interactions. As organic compounds, these molecules, the components of the nanofibers jussara and the polymer, possess a significant amount of oxygen atoms and, especially hydrogen atoms, which promotes hydrogen-bridge type interactions, besides the fact that the polymer has a hydrophobic character and thus increases polar interactions and nonpolar repulsions with lipophilic molecules.

Comment: For the thermal stability, the authors perform experiments at two elevated temperatures. What about room temperature?

Response: This analysis aimed to investigate temperatures that foodstuff products submitted in the food industry to evaluate the potential use of nanostructures to prevent antioxidant activity loss during processes such as pasteurization. This information was added to the manuscript.

Comment: A similar work on composite materials via electrospinning is suggested, Chin. Chem. Lett., 32, 3372 (2021).

Response: The suggested reference was added.

Author Response File: Author Response.pdf

Reviewer 2 Report

The manuscript is very interesting and novel. The methodology used is adequate and sufficient. The results support the discussion. Briefly, the authors propose the potential of electrospinning composites in processed foods, considering the digestion process. However, I have the following comments.

I. Major Comments:

1. Considering the results, I suggest including a figure that shows the results obtained in the discussion.

2. I suggest briefly discussing the bioavailability of anthocyanins, particularly in the development of functional foods. PMID: 34814808

II. Minor comments:

2. Improve the writing of the objective of the study.

3. I suggest including a brief paragraph on projections and applications, especially in food, nutrition and health.

Author Response

We would like to thank the reviewers for their valuable comments and suggestions for our manuscript. We have modified the manuscript according to the recommendations, and the detailed, point-by-point corrections are listed below. The modifications requested were extremely important to improve our work. All sentences/words listed below are highlighted in the revised version of the manuscript.

Comment: The manuscript is very interesting and novel. The methodology used is adequate and sufficient. The results support the discussion. Briefly, the authors propose the potential of electrospinning composites in processed foods, considering the digestion process. However, I have the following comments. Considering the results, I suggest including a figure that shows the results obtained in the discussion.

Response: Figure 3 was added as requested.

Comment: I suggest briefly discussing the bioavailability of anthocyanins, particularly in the development of functional foods. PMID: 34814808

Response: The suggested reference was added.

Comment: Improve the writing of the objective of the study.

Response: The objective was rewritten as required.

Comment: I suggest including a brief paragraph on projections and applications, especially in food, nutrition and health.

Response: The paragraph was added.

Author Response File: Author Response.pdf