Optimization of Spray Drying Conditions for a Capsicum chinense Leaf Extract Rich in Polyphenols Obtained by Ultrasonic Probe/NADES
, Juan Valerio Cauich-Rodríguez 2, Manuel Octavio Ramírez-Sucre 1 and Ingrid Mayanin Rodríguez-Buenfil 1,*Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsComments for ChemEngineering-3281230
This is an interesting work to optimize the spray drying conditions to produce polyphenol-rich microencapsulates from habanero chili pepper leaf extracts using both USP with NADES. It contains competent experimentation and useful results. However, the description and in-depth analysis of the results need to be strengthened. The manuscript is well written from a scientific and linguistic point of view. Nevertheless, some points need to be taken into account in the paper and are missing. I will suggest some modifications that would make it more fruitful.
1. Abstract: The abstract should be more concise, highlighting key points.
2. A space is required between the number and the unit.
3. Line 51: Please correct “this” to “these”.
4. Line 78: Please correct “were” to “was”.
5. Line 82: Please correct “MEOH” to “MeOH”.
6. Line 116: The middle bracket is redundant.
7. Lines 153, 193, 516-517, etc.: Please correct “ml” to “mL”.
8. Line 157: This sentence lacks a full stop.
9. Line 163: Please correct “resulted” to “resulting”.
10. Line 191: Please correct “C18” to “C18”.
11. Lines 209, 238: Only formula 3 appears in the manuscript, with formulas 1 and 2 missing.
12. It is necessary for the authors to redraw the tables and rearrange the formulas in accordance with the journal template.
13. Line 220: The full stop is redundant.
14. Line 237: Colour parameters (L*, a*, b*) should be in italics.
15. How did the authors determine the experimental range of values for GG and IT?
16. Table 1: Please correct “EAG” to “GAE”. Also, in section 2.5.4, the authors state that the ABTS results will be expressed as mg eq Trolox/ 100g of powder, whereas in Table 1 it is expressed as mg eq Trolox/g of powder, please explain.
17. Line 360: The citation mentioned here are not reflected in the references.
18. Line 435: Table 5 is not available in the manuscript.
19. For section 3.3, the authors mention that samples under different IT conditions present different TPC or antioxidant capacity. But the connection to the microstructure is not very convincing. Please strengthen this part of the analysis.
20. Lines 466 and 474: Please revise the statement on spectral range.
21. Lines 536-541: Please rewrite.
22. Please clarify the relationship between Figure 4 and Figure S2. With regard to Figure S2, it is not referenced in the text. Moreover, is there a corresponding color image for Figure 4, which is not conducive to viewing in the black and white images currently presented in the manuscript?
23. As can be observed, the data presented in Tables 1 and S3 were subjected to an analysis of significant differences through the segregation of groups 1-8 and 9-12. However, Table 3 was analysed for significant differences by taking groups 1–12 as a whole. The authors are kindly requested to provide an explanation as to why the data were treated in this manner.
Comments for author File: 
Comments.pdf
Author Response
"Please see the attachment."
Author Response File: 
Author Response.docx
Reviewer 2 Report
Comments and Suggestions for AuthorsThe authors investigated the optimal spray-dry parameters for microencapsulation of habanero leaf extracts obtained using a sonic probe and NADES. This research article is interesting, however, I would suggest a revision, after which the paper should be published.
1. Please revise the sentence: “Furthermore, spray drying is an easily scalable technology that has been proven to preserve microcapsules phenolic compounds for up to 21 weeks [26], establishing it as a feasible method for maintaining the integrity of phenolic compounds extracted through the Ultrasonic Solvent Probe (USP) in conjunction with Natural Deep Eutectic Solvents (NADES).”
2. Please revise the sentence: “The aim of this research is to optimize the spray drying conditions to produce polyphenol- rich microencapsulates from habanero chili pepper leaf extracts using both USP with NADES”. It sounds as microencapsulates are obtained using USP with NADES.
3. Please describe the drying process for habanero pepper leaves in the Materials and Methods section.
4. Please explain why the NADES extraction was performed with 68% of water, if the optimal conditions selected in previous study (Avilés-Betanzos, K. A., Cauich-Rodríguez, J. V., González-Ávila, M., Scampicchio, M., Morozova, K., Ramírez-Sucre, M. O., & Rodríguez-Buenfil, I. M. Natural Deep Eutectic Solvent Optimization to Obtain an Extract Rich in Polyphenols from Capsicum chinense Leaves Using an Ultrasonic Probe. Processes 2023, 11, 1729. https://doi.org/10.3390/pr11061729) were with 12% water.
In general, if the water content is higher than 50%, NADES may be considered an aqueous solution to its constituents rather than a eutectic mixture.
5. X1 and X2 parameters should be described below Table 1. Also, please check the encoded -1 and 1 values in X2 column.
6. Why only GG was selected as variable in CCD, and not maltodextrin and modified starch?
In this paragraph (rows 147-152): ”Spray drying of the EHPL was carried out according to the conditions reported by Chong et al. [27] with some modifications. The EHPL solution to spray was prepared at 5%, by weighing 10 g of the EHPL in a 1:3 w/w ratio (EHP:Encapsulating agent) with the encapsulating agents (maltodextrin, Guar gum, modified starch) at a temperature of 45°C. The percentage of each encapsulating agent in the final preparation was established ac- cording to the CCD 22.” It is not clear how much maltodextrin and modified starch was in the mixture. Also, what is EHP? Please make it more clear for reading.
7. Row 243, what is SE?
8. Rows 355-365. Please provide description of each variable influence on the TPC and Ax, taking into account their positive or negative effects.
9. Row 372, “microcapsules of EHPL obtained by ultrasonic probe using deep eutectic” this sounds as the microcapsules are obtained by ultrasonic probe using deep eutectic, which is not the case. Please revise this in the whole manuscript.
10. Row 400, something is missing “()”
11. Rows 410-415. Please describe the impact of each variable. In my opinion, Figure 1c should be described in this paragraph. Have you performed validation analysis for this model?
12. Have you predicted the optimal microencapsulation conditions tacking into account all three statistically significant models (TPC, Ax, neohesperidin content)?
13. Row 468, which extract is considered as “spry dried extract (SE)”? Also, please check the grammar.
14. Rows 479-486: “For the encapsulating agents M0 (2920 cm−1), GG (2919 cm−1), AM (2924 cm−1) and the microcapsules M5 (2924 cm−1) and M12 (2925 cm−1), peaks can be observed between 2920 cm−1and 2925 cm−1, which are associated with the stretching vibrations of CH and CH2 bonds, due to the carbonaceous structure of the encapsulating agents [14].
At Figure 4, the band corresponding to CH and CH2 bonds for the extract (3307 cm⁻¹) exhibits a larger peak area compared to the encapsulating agents like maltodextrin (3284 cm⁻¹) and guar gum (3304 cm⁻¹). The microencapsulated sample M5 shows a smaller peak area (3286 cm⁻¹) than both the extract and the encapsulating agents.”
This paragraph is confusing. Firstly, it was described that bands corresponding to CH and CH2 bonds are around 2920 cm−1, and in the next sentence are around 3300 cm⁻¹, while at the beginning of section it was written that a broad peak observed around 3200-3600 cm⁻¹ corresponds to the O-H stretching vibration.
The analysis of the FTIR spectra should be corrected and performed more comprehensively. It should also include description of bands presented in the spectral area from 800 to 1650 cm⁻¹. This analysis should be connected with the rows 535-547. Why is Figure S2 included in the Discussion section when it is the same as Figure 4?
Abbreviations should be uniformed.
15. “In the case of NADES- based extracts, the glass transition temperature (Tg) of the eutectic components (e.g., cho- line chloride and glucose) should be considered, as their Tg (−16.78°C) is lower than the ITs typically used (140-200°C) [37,38].”
Please explain how you overcome this limitation.
16. Row 509: Please explain this in more detail: “…like methods reported for powdered honey”.
Author Response
"Please see the attachment."
Author Response File: Author Response.docx
Reviewer 3 Report
Comments and Suggestions for AuthorsThe manuscript submitted by Avilés-Betanzos et al. intitled “Optimization of Spray Drying Conditions for a Capsicum chinense Leaf Extract Rich in Polyphenols Obtained By Ultrasonic Probe/NADES” reports the optimization of the microencapsulation parameters for habanero leaf extracts, obtained using a sonic probe and NADES, by spray-drying with maltodextrin, guar gum, and modified starch. This is an interesting work that appears in the context of a previous papers published by the authors, in which the extraction process using a sonic probe and NADES was developed and optimized. The manuscript is, in general, very well written and structured, and it is very complete in terms of scientific data and characterization techniques used. The results that were obtained by the authors are important for the scientific community and very interesting, since they were able to obtain microcapsules with improved polyphenol content and antioxidant capacity. Thus, I do recommend the publication of this manuscript in ChemEngineering Journal after addressing some major revisions, that are listed below:
1 – In general, the standard deviation presented by the authors reveals that there is not relevant heterogeneity between the assays; were they performed with leaves from the same plant? Or different plants? Did you have any idea if these values can vary much according with the plant used?
2 – Do the authors think that the best results obtained (high polyphenol content and antioxidant capacity) for the final samples are related with the preferential enrichment in the microcapsule of specific compounds (one or more)? Do you think that a previous concentration step would help to increase their potential?
3 – How the results obtained by the authors for the polyphenol content, antioxidant capacity and microcapsules morphology of the plant extract compares with the individual compounds used for the microencapsulation and/or other control? This is not clear in the manuscript.
4 – More details can be added to the Materials and Methods section, for example more information on the preparation of samples, solvents used, etc.
5 – What was the rationale behind the chosen spray drying condition for the central point of CCD? Did the authors based on any preliminary results that are not shown in the manuscript? Some explanation on this rationale would be greatly appreciated to improve the quality of the manuscript.
6 – In Figure 2, the amounts of each individual polyphenol that were identified in the microcapsules are presented; do you have any idea on how these values compare with the reference value of each compound in the original biomass?
7 – Line 400: there are two brackets without information presented.
8 – Although there is mentioned that currently there is no data available on the production of microcapsules using spray drying techniques for extracts derived from NADES, do you have any idea if the microscopical appearence of these capsules are appropriate for the desired applications (e.g. nutraceuticals)? Do the authors expect any change on the morphology/properties of the microcapsules when they are in a more complex real matrix?
9 – Do you have any evidence on the potential toxicity of the NADES used for the extraction, since they are also present in the final product/powder, that will be then applied in the different human applications? There are any studies on its effect in human cell lines, for example?
Author Response
"Please see the attachment."
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsThe revised manuscript is much improved, however, the manuscript still has many problems. These are shown below.
1. “%” is not a unit of measurement, so there is no need for a space between it and the number at all.
2. In line 110, two periods appear.
3. The formatting of Table 1 is very terrible and still needs further adjustment. Why is “Optimization” capitalized in the title of table 1? The box at the top of the table needs to be added. The numbers in “X1” and “X2” should be subscripted, and none of the letters indicating significant differences in the data for the ABTS group are in superscript form.
4. In lines 23, 346, 361, 470-471, the expression “number + °C” still lacks a space.
5. In line 257, there is an extra space before the period.
6. In line 313, there is an error in the format of R2.
7. Line 330, why should “Total Polyphenol Content” be capitalized?
8. The problem with the expression “L*, a*, b*” has been raised before, but the authors have changed only a small part of it, so please read through the manuscript and revise it. For example, chapter 3.2.
Author Response
"Please see the attachment."
Author Response File: Author Response.pdf
