Round 1

Reviewer 1 Report

The use of waste products to recover valuable compounds from them is an important issue that deserves attention, especially in terms of optimizing recovery. In my opinion, the manuscript is well designed and the results are presented in a clear and legible manner, without my objections.

I read the manuscript with interest, and I have only some minor comments:

Abstract:

The first three sentences of the abstract are fragments more suited to the Introduction than to the Abstract section. It is difficult to determine on their basis why you were interested in anthocyanin colorants from acerola. In the text of the manuscript, I found several more appropriate sentences highlighting the benefits of anthocyanins. I think they should be converted.

Introduction

Line 50; 61; 249  – “manly” à mainly?

Line 52-53 “producing new food ingredients” - this wording is somewhat misleading; research has been conducted on the production of new food ingredients? or on isolating them from natural resources or waste products. There are no citations here to determine what type of research the authors had in mind.

Line 63 – “This process depends on..” or “It depends on..”

Line 78: “following factors:” or “the effects of the ethanol percentage, temperature, and time”

Materials

Were the materials received from the company a waste product?

Line 180: abbreviations have been explained above, so please use them when discussing the results

Line 183: the highest

192 – Eq 1 is missing?

198 Table 1 should not be bolded

233, 237 – (5)

Table 3 – S or E??

250-251 the sentence was repeated written above (243-244)

291 – acerola waste product not acerola; it can be assumed that different conditions would be obtained for acerola than for its waste product

Minor editing of English language required. 

Author Response

Author's Reply to the Review Report (Reviewer 1)

The use of waste products to recover valuable compounds from them is an important issue that deserves attention, especially in terms of optimizing recovery. In my opinion, the manuscript is well designed and the results are presented in a clear and legible manner, without my objections.

I read the manuscript with interest, and I have only some minor comments:

Response: The authors are grateful for the Reviewer's positive comments on the manuscript and all the constructive remarks, which were carefully taken into consideration during the preparation of the revised version. These inputs have significantly contributed to enhancing the overall quality of the manuscript.

 

Abstract:

The first three sentences of the abstract are fragments more suited to the Introduction than to the Abstract section. It is difficult to determine on their basis why you were interested in anthocyanin colorants from acerola. In the text of the manuscript, I found several more appropriate sentences highlighting the benefits of anthocyanins. I think they should be converted.

Response: We are grateful for the constructive suggestion that has been addressed in the revised manuscript.

 

Introduction

Line 50; 61; 249  – “manly” à mainly?

Response: Corrections have been made accordingly.

 

Line 52-53 “producing new food ingredients” - this wording is somewhat misleading; research has been conducted on the production of new food ingredients? or on isolating them from natural resources or waste products. There are no citations here to determine what type of research the authors had in mind.

Response: Thanks for the observation. The text has been improved accordingly.

 

Line 63 – “This process depends on..” or “It depends on..”

Line 78: “following factors:” or “the effects of the ethanol percentage, temperature, and time”

Response: Corrections have been made accordingly.

 

Materials

Were the materials received from the company a waste product?

Response: The waste material received from the company consisted of acerola fruits without the quality standards required for commercialization. These fruits were either of the wrong caliber or had damaged (cracked or pitted) parts. The subsection has been improved accordingly.

 

Line 180: abbreviations have been explained above, so please use them when discussing the results

Line 183: the highest

Response: Changes have been made accordingly.

 

192 – Eq 1 is missing?

Response: Eq. 1 is presented in the methodology section.

 

198 Table 1 should not be bolded

233, 237 – (5)

Table 3 – S or E??

Response: Corrections have been made accordingly.

 

250-251 the sentence was repeated written above (243-244)

Response: Thanks for the observation. Since we first referred to the 3D graphs where only one of the three factors is missing (Figure 2), in the 2D graphs (Figure 3) there are two unplotted factors. We believe that it is important to provide this detailed information, as there are studies that place the unplotted factor(s) at the center value of the experimental design.

 

291 – acerola waste product not acerola; it can be assumed that different conditions would be obtained for acerola than for its waste product

Response: Thank you for the observation. The correction has been made accordingly.

 

Minor editing of English language required. 

Response: The manuscript has been reviewed for English language and sentence construction.

Author Response File: Author Response.pdf

Reviewer 2 Report

The authors present an interesting study concerning the dynamic maceration of powdered acerola fruit waste to obtain an anthocyanin-enriched extract for application as natural colorant.

The purpose of the research is clear, the reported results are adequately discussed and the paper il well written. However, it presents some criticisms that make it unacceptable in its current form. Thus, I recommend to publish the paper in Agronomy after major revision.

-      -  In the Introduction (L65-67) authors affirm: “Among the techniques currently used to extract anthocyanins, dynamic maceration stands out as being a simple, easy-to-perform, and relatively inexpensive technique that allows the use of food-grade solvents, such as water and hydroalcoholic mixtures [17,18].” Authors should clearly state the reason for which hydroalcoholic mixtures are used for the recovery of anthocyanins (water soluble pigments).

-     -   Among the factors investigated (ethanol percentage, temperature, and time) the variable solid:liquid ratio was not considered. Why? It is a very important parameter.

-     -   The colorimetric characterization of the recovered extracts should be performed in order to supply information about color quality. This is a very important aspect, especially in view of application as natural colorant in food.

Author Response

Author's Reply to the Review Report (Reviewer 2)

The authors present an interesting study concerning the dynamic maceration of powdered acerola fruit waste to obtain an anthocyanin-enriched extract for application as natural colorant.

The purpose of the research is clear, the reported results are adequately discussed and the paper il well written. However, it presents some criticisms that make it unacceptable in its current form. Thus, I recommend to publish the paper in Agronomy after major revision.

Response: The authors are grateful for the Reviewer's positive comments on the manuscript and all the constructive remarks, which were carefully taken into consideration during the preparation of the revised version. These inputs have significantly contributed to enhancing the overall quality of the manuscript.

 

- In the Introduction (L65-67) authors affirm: “Among the techniques currently used to extract anthocyanins, dynamic maceration stands out as being a simple, easy-to-perform, and relatively inexpensive technique that allows the use of food-grade solvents, such as water and hydroalcoholic mixtures [17,18].” Authors should clearly state the reason for which hydroalcoholic mixtures are used for the recovery of anthocyanins (water soluble pigments).

Response: We appreciate the constructive suggestion. The introduction has been improved accordingly.

 

- Among the factors investigated (ethanol percentage, temperature, and time) the variable solid:liquid ratio was not considered. Why? It is a very important parameter.

Response: The authors agree with the Reviewer. Indeed, the solid/liquid ratio is an important factor in extraction processes. However, conducting experiments with four factors is quite complex and labor-intensive. Additionally, increasing this factor values usually leads to higher extraction rates until saturation occurs, while predicting the impact of the other three factors becomes less predictable. Unfortunately, we are unable to conduct additional experiments. Nonetheless, we emphasized the significance of evaluating the influence of this factor in future studies descried in the conclusion section.

 

- The colorimetric characterization of the recovered extracts should be performed in order to supply information about color quality. This is a very important aspect, especially in view of application as natural colorant in food.

Response: The authors agree with the Reviewer. It would have been interesting to have measured the color of the acerola fruit waste extracts. However, the color intensity can be related to the concentration of anthocyanins in the extract. Therefore, the conditions that maximize the anthocyanin extraction are those that produce a coloring extract with a more intense color. We are unable to conduct this additional analysis, but we highlighted its importance as a future study.

Author Response File: Author Response.pdf

Reviewer 3 Report

Agronomy 25400601

 

Dynamic Maceration of Acerola (Malpighia emarginata DC.) 2 Fruit Waste: An Optimization Study to Recover Anthocyanins, by Cerino et al.

 

The document describes the optimization of an extraction method for anthocyanins from Acerola fruit waste. Extraction was carried out my dynamic maceration and the optimum conditions of ethanol concentration and time and temperature of extraction were investigated by the use of mathematical and statistical means. This means that only a few selected combinations of the parameters were required to determine the optimum conditions required to obtain high yield and purity.

 

General comments.

The chemical analysis of the work was state of the art and produced novel information. The document is well written and easy to read and understand with minor linguistic and text errors being noted, for which improvements are listed below.

Specific comments.

Line 35. …has become important…

42. …compounds, within…effects, when added…

46. …ingredients, and the…

50, 61, 249. Replace manly with mainly

56. …and their structural composition [9]. They exhibit…

59. …anthocyanins, that…

64. …and time, and type…

66. …technique, that allows…

79. …temperature and time… (remove comma)

87. Describe the method how the freeze-dried material was broken or milled.

133. Replace quantified with quantify

192. What is the meaning of the following? ...(1 Error etc)

277. …by applying these…

323. …key factors, time, temperature…and ethanol…

326. Correct stablished to established

327. …and a recovery…

minor errors. see report

Author Response

Author's Reply to the Review Report (Reviewer 3)

Dynamic Maceration of Acerola (Malpighia emarginata DC.) 2 Fruit Waste: An Optimization Study to Recover Anthocyanins, by Cerino et al.

The document describes the optimization of an extraction method for anthocyanins from Acerola fruit waste. Extraction was carried out my dynamic maceration and the optimum conditions of ethanol concentration and time and temperature of extraction were investigated by the use of mathematical and statistical means. This means that only a few selected combinations of the parameters were required to determine the optimum conditions required to obtain high yield and purity.

General comments.

The chemical analysis of the work was state of the art and produced novel information. The document is well written and easy to read and understand with minor linguistic and text errors being noted, for which improvements are listed below.

Response: The authors deeply appreciate the Reviewer's positive comments on the manuscript and all the constructive remarks, which were carefully taken into consideration during the preparation of the revised version. These inputs have significantly contributed to enhancing the overall quality of the manuscript.

 

Specific comments.

Line 35. …has become important…

42. …compounds, within…effects, when added…
43. …ingredients, and the…

50, 61, 249. Replace manly with mainly

56. …and their structural composition [9]. They exhibit…
57. …anthocyanins, that…
58. …and time, and type…
59. …technique, that allows…
60. …temperature and time… (remove comma)
61. Describe the method how the freeze-dried material was broken or milled.
62. Replace quantified with quantify
63. What is the meaning of the following? ...(1 Error etc)
64. …by applying these…
65. …key factors, time, temperature…and ethanol…
66. Correct stablished to established
67. …and a recovery…

Response: All corrections have been made in the revised manuscript.

 

Comments on the Quality of English Language

minor errors. see report

Response: Corrections have been made according to the provided report.

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments for author File: Comments.pdf

Author Response

Author's Reply to the Review Report (Reviewer 4)

Introduction:

Line 61: To change “manly” …by “mainly”

Response: The correction has been made accordingly.

 

Line 65 - 67: The authors should explain in more detail what they are referring to when they write "dynamic maceration", perhaps for them it is a well-known and widely used term, but not for a large number of readers to whom this manuscript is directed. It is appreciated that there is a more exhaustive explanation.

Response: Thanks for the constructive recommendation. An explanation for the dynamic maceration method has been added to the introduction.

 

Line 76 - 78: The authors must explain where they get the "powdered acerola fruit waste" since it is the main source that generates waste, from which the work is being positioned.

Response: Thanks for the constructive suggestion. The plant material section has been improved to better explain how the powdered acerola fruit waste was obtained.

 

Line 78 - 80: Justify why only the research is based on the factors ethanol percentage, temperature, and time and other relevant factors such as pH, and the acidity of the medium, among others that are important in all maceration of this type, are not taken into account. It is possible that these are taken into account as control variables of the experiment, but it must be said and explained.

Response: The authors agree with the Reviewer. In fact, the pH is a relevant factor during anthocyanin extraction. In this study, the solvent was acidified to pH 3 with citric acid and kept constant during extraction. According to the literature, this pH value is adequate to stabilize the flavylium cation and increase the intensity of the red hue of anthocyanins. Therefore, we decide to fix the pH value during extraction, while the other three factors and the respective range of values were selected as relevant based on previous optimization studies of our research group (as indicated in section 2.2.). However, the importance of pH and other factor, as well as the suitability of pH 3 during dynamic maceration, were indicated in the introduction of the revised manuscript.

 

Materials and Methods

Line 85: What the authors refer to with "Acerola fruits without the required standards for commercialization", should be explained better, as they are important for the present study.

Response: Thank you for the constructive suggestion. The plant material section has been improved accordingly.

 

Results and Discussion

Line 153 - 163. A large part of this paragraph should be in the introduction of the present study. There I would answer many questions that some readers may ask themselves. Besides, being here does not put him in a good place.

Response: Thanks for the constructive suggestion. The paragraph information has been moved to the introduction as suggested.

 

The experimental design carried out is well executed and discussed. The responses of the models and the different figures more than support the entire discussion. Well-explained and reasoned papers such as this study are appreciated. Comparisons with other works carried out on acerola were also reasons for discussion and comparison with the results found here.

Response: The authors are grateful for the Reviewer's positive comments on the manuscript and all the constructive remarks, which were carefully taken into consideration during the preparation of the revised version. These inputs have significantly contributed to enhancing the overall quality of the manuscript.

 

 

Author Response File: Author Response.pdf

Reviewer 5 Report

本文 使用响应面方法来确定最佳条件，该条件具有 一些应用程序，但不是很创新。

Comments for author File: Comments.pdf

Minor editing of English language required.

Author Response

Author's Reply to the Review Report (Reviewer 5)

This paper uses response surface methodology to determine optimal conditions, which has some application but is not very innovative.

There are some problems, which must be solved before it is considered for publication.

Response: The authors appreciate the Reviewer's constructive remarks, which were taken into consideration during the preparation of the revised version.

 

1. Remove the bracketed part of the title.

Response: Thanks for the suggestion, but we believe that it will be important to indicate the common and scientific name of this species in the title of the manuscript.

 

2. Reduce this section of the abstract." Acerola (Malpighia emarginata DC.) is a tropical fruit rich in vitamin C and polyphenols, which provide numerous health benefits. However, like other agricultural products, the industrial processing of acerola fruit generates biowaste that, if not properly managed, can have negative con- sequences at economic, environmental, and social level. Therefore, the suitability of acerola fruit waste for producing anthocyanin colorants by dynamic maceration was investigated. "

Response: The aforementioned abstract section has been reduced as suggested.

 

3. With reference to 2.4.2 of the text, please describe in detail the procedure for obtaining the supernatant. Also, is it feasible to pass the supernatant through a syringe filter disks only?

Response: Sections 2.3. and 2.4. have been improved as suggested to better explain the procedure. After dynamic maceration, the mixtures were centrifuged and the supernatants were filtered through Whatman No. 4 filter paper. These filtrate solutions were used to determine the extraction yield and for anthocyanin analysis. The filtrate solutions were further filtered through 0.22 µm syringe filter disks prior to their injection into the HPLC system.

 

4. This paper presents three factors affecting the extraction including time, temperature and extraction solvent. In this paper, ethanol was used as extraction solvent, but the extraction solvent also has a great effect on the extraction rate, is it possible to try the effect of different solvents on the extraction.

Response: We appreciate the Reviewer observation. In fact, the extraction solvent used in this study (that consisted of ethanol-water mixtures) induced significant effects on the extraction and also interacted positively with the other two factors. Ethanol was chosen because it is a generally recognized as safe (GRAS) solvent permitted for production of foodstuffs and food ingredients (this sentence has been added to the manuscript and the introduction was improved accordingly). Methanol was also a possible solvent, but this is not allowed in the food industry. In our study, it is interesting to note that the solvent differently affected the two dependent variables investigated (extraction yield and content of anthocyanins). Thus, selectivity for anthocyanins can be achieved by applying these time-saving and eco-efficient conditions of dynamic maceration.

 

5. Conclusions needs more in it, as it's more of an afterthought. The authors are suggested to highlight important findings and include afterthought of this work.

Response: We appreciate the constructive suggestion. The conclusions section has been improved accordingly.

 

 

Author Response File: Author Response.pdf

Reviewer 6 Report

Comments are as follows:

1. Authors need to clarify what their study brings in novelty, compared to the similar studies in scientific literature that are presented. What is the originality of the work?

2. Moisture content of the sample material has to be included.

3. The abbreviations should be defined just the first time they are mentioned in the text and used as such throughout the text. 

4. The text from line 153-163 has to be moved to the Introduction section.

5. Conclusions section has to be improved. In general, there is a lack of practical applications of the findings and the sufficient importance of this study.

6. Authors should check the text for typos.

7. Six and eight self-citations by Jose Pinela and Lillian Barros, respectively, has to be revised and reduced. 

Author Response

Author's Reply to the Review Report (Reviewer 6)

1. Authors need to clarify what their study brings in novelty, compared to the similar studies in scientific literature that are presented. What is the originality of the work?

Response: We appreciate the constructive recommendation. The introduction has been improved to better explain the novelty and innovative features of this work. As discussed in the manuscript, similar studies in the scientific literature were based on experimental data from colorimetric methods to optimize their processes, which may not be the most appropriate approach to follow in optimization studies due to possible selectivity and sensitivity limitations of these quantification methods. Furthermore, such optimizations were made for total compounds rather than individual anthocyanins. Thus, our work presents a step forward regarding the analytical methods used in the chemical analysis.

 

2. Moisture content of the sample material has to be included.

Response: The moisture content has been indicated as suggested.

 

3. The abbreviations should be defined just the first time they are mentioned in the text and used as such throughout the text.

Response: The constructive suggestion has been attended in the revised version.

 

4. The text from line 153-163 has to be moved to the Introduction section.

Response: The constructive suggestion has been attended in the revised version.

 

5. Conclusions section has to be improved. In general, there is a lack of practical applications of the findings and the sufficient importance of this study.

Response: We appreciate the constructive suggestion. The conclusions section has been improved accordingly.

 

6. Authors should check the text for typos.

Response: Corrections have been made accordingly.

 

7. Six and eight self-citations by Jose Pinela and Lillian Barros, respectively, has to be revised and reduced.

Response: The self-citations have been reduced accordingly.

 

The authors appreciate the Reviewer's constructive remarks, which were taken into consideration during the preparation of the revised version. These inputs have contributed to enhancing the overall quality of the manuscript.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The manuscript has been revised according to the suggestions

Author Response

Author's Reply to the Review Report (Reviewer 2)

The manuscript has been revised according to the suggestions.

Response: The authors thank again all the reviewer's constructive suggestions that helped to improve the overall quality of the manuscript.

Author Response File: Author Response.pdf

Reviewer 5 Report

The research in the article has certain application value, but it lacks innovation and depth, and there is still a certain gap to be published in Q1 journals.

Quality of English Language is fine.

Author Response

Thank you for your comments. All your suggestions were made in the manuscript. 

Author Response File: Author Response.pdf

Reviewer 6 Report

1. Authors need to clarify what their study brings in novelty, compared to the similar studies in scientific literature that are presented. What is the originality of the work?

2. The authors should state the moisture content of dried material used for extraction.

 

Author Response

Author's Reply to the Review Report (Reviewer 6)

1. Authors need to clarify what their study brings in novelty, compared to the similar studies in scientific literature that are presented. What is the originality of the work?

Response: To the best of the authors' knowledge, this is the first optimization study focused on individual anthocyanins rather than total compounds, thus bringing novel insights into the impact of the tested extraction factors. In fact, the similar studies available in the literature and discussed in the manuscript are optimization studies performed with experimental data from colorimetric assays, which may present selectivity limitations and overquantification issues. Furthermore, these previous optimization studies were conducted for total compounds (total anthocyanins, total phenolics, and total flavonoids) rather than individual anthocyanins. It is noteworthy that the studied plant matrix has two different anthocyanins, one cyanidin glycoside and one pelargonidin glycoside, which could be differently affected by the extraction. Thus, our work presents a step forward regarding the analytical methods used in the chemical analysis and therefore it brings novel insights into the impact of the tested extraction factors. To address the reviewer's concern, section 3.3. of the revised manuscript has been improved accordingly.

 

2. The authors should state the moisture content of dried material used for extraction.

Response: As indicated in the manuscript, the fresh acerola waste sample with a moisture content of 89.7% was freeze-dried to complete dryness and then stored vacuum-sealed at -20 °C until used to prevent moisture absorption and pigment degradation. Therefore, it was considered that the powder sample used in the experiment was completely dry. The manuscript has been improved accordingly.

 

The authors thank again all the reviewer's constructive suggestions that helped to improve the overall quality of the manuscript.

Author Response File: Author Response.pdf

Round 3

Reviewer 5 Report

The paper do much experiment on the optimization condition about the influence of time and temparature on the yield. But the yield just ranged from 48.02% to 63.21%. What's the significance and value on the enhance of just about 10% yield? Is there significant improvement in active function or economic value? If not, I think the significance and innovationof research is low. So the authors must do some improment on the clarification of the significance or the innovation of research.

The paper do much experiment on the optimization condition about the influence of time and temparature on the yield. But the yield just ranged from 48.02% to 63.21%. What's the significance and value on the enhance of just about 10% yield? Is there significant improvement in active function or economic value? If not, I think the significance and innovationof research is low.