Eco-Designing Cosmetic Products while Preserving the Sensorial-Application Properties: An Instrumental Approach toward Sustainable Formulations

Round 1

Reviewer 1 Report

The manuscript entitled "Eco-designing cosmetic products without performance trade-offs: an instrumental approach towards sustainable formulations," conducted by Tafuro et al., presents the reformulation of three cosmetic products using an eco-sustainable approach by replacing synthetic texturizers and rheological modifiers with nature-derived alternatives. Rheological and texture analysis studies were performed to identify the optimal combination of ingredients and their levels to achieve products with similar sensorial characteristics as the original formulations. Sensory properties of the formulations were assessed by a panel of volunteers, and the data were compared with the results from instrumental tests. Although the level of novelty is not exceedingly high, the study was rigorously conducted, and the obtained results were thoroughly explained. The findings provide valuable insights for better understanding ingredient selection from an eco-sustainable perspective and for future studies involving the reformulation of traditional cosmetics within the eco-design framework. However, it is suggested that the authors revise certain aspects for better structuring of the information:

1. In my opinion, presenting the chosen ingredients as more sustainable alternatives in a table format, along with information about the raw material supplier (lines 119-146), would enhance clarity.

2. The novelty of this work should be emphasized, and a comparison with related studies from the literature should be included.

3. Some points to consider for future studies should be provided, as this reformulation study represents only the first step toward changing the formulation to create a more sustainable product.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

The study is well structured, the methods used are pertinent and the results are plausible. The sudy and the characterization of the formulations developed it is well done and my suggestion is to publish this work after Major revisions, see below.

1.      The authors should describe more correctly the equipment used (centrifuge, homogeneizer Silverson,….) in all manuscript. Please add: company, city and country in brackets.

2.      Describe software of rheometer used. Please add: company, city and country.

3.      Most of the raw materials used are trade names. Please add ®

4.      The material and methods (section 2) should be corrected and divided into subchapters to improve understanding. For example, section Elaboration of emulsions; Rheological behaviour; Texture analyses, Stability test, Statistical analyses,…

5.      Line 247: (G and H), What is G?  Can it be S?…..

6.      Why you didn’t prepare F1Zr075? Explain it

7.      Why you prepare F1Zv075k01 (F1Zv075: separation) and not F1Zv01k01 (F1Zv1: Stable)? Explain it

8.      After changing for eco-friendly alternatives texturizer agents authors do reheological analyses. Do the authors perform flow and viscosity measurements after adding rheological agents? Explain it.

9.      Line 334. What is E15? Can it be EG? Explain it

10.  The authors would have to expand information on the non-invasive in vivo studies on healthy volunteers. Describe more detailed the in vivo study methodology and include the Approval date of the Ethical Committee. Add chacateristics of subjects (age,  ..), Climatic chamber (temperature, RH,..), Test procedure,… Add subchapter about statistical and procedure analyses. Provide additional comments on the statistical significance of their results. What amount of samples did they apply? How did the authors apply the samples? What was the control in these experiments? application surface area?

11.  Describe parameters of Careau-Yasuda mathematical model.

12.  The paragraphs on sample reformulations are very long and confusing. For this reason, I advise the authors to add the subchapters: modification of synthetics texturizers, modification of rheological agents, modifications of silicone emollients to improve understanding.

13.  Table 8: What is F1Zr? Can it be F2Mr? Explain it

14.  In my opinion manuscript is very long and many texture curves (8, some of them could be inserted in the supplementary material). On the other hand, there is no graph regarding flow and viscosity measurements.

15.  The pH of skincare products plays a crucial role in determining their effectiveness. Furthermore, rheological agents like Carbopol-type are pH-dependent. Do the autors consider necessary determination of pH? Explain it

16.  The particle size distribution has a significant influence on several fundamental properties of the final emulsion: stability, viscosity, optical properties, mechanical strength. Use DLS and/or other techniques to determine Particle size.

17.  Some figures are not clear to see and read the text. Please improve the quality of the figures and make them consistent and clearer.

18.  Change minutes for min line 157, 283

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

The subject matter of the paper is in line with current scientific trends regarding work on modern cosmetic products. It points to the increased emphasis on sustainability, which has become a major imperative in the global cosmetics industry, forcing companies to develop innovative products that can minimize environmental impact. The article has the potential to attract a fairly wide readership. It is also concluded that the research results presented have great practical potential. The work has great potential, but please try to improve it.

General observations:

·        In the Result and discussion section, the authors present the results of the study and their interpretation. They refer to the literature only by stating the literature item in square brackets. Currently, in scientific papers, one would need to refer one's findings to previous studies in more detail. E.g., Authors XXXX in their paper showed instead that....

·        Your work is important in the direction of sustainable development, but there are many errors in the way it is presented. The work developed a great deal of formulations. While reading the work I got lost many times. Please introduce F1, F2 and F3 base formulations with INCI names and concentrations.

Specific comments:

1. Lines 2,3. Suggests that the Authors rethink the wording "without performance".

2. Lines 5,6. Remove unnecessary spaces between names and numbers in superscript.

3. Line 11. Remove unnecessary semicolon, insert comma.

4. Tables 1, 2, 3. Showing cosmetic formulations should be changed. The tables in column two show not the composition but the functions of the ingredients. The composition is discussed below the tables, which is not very convenient for the reader. I suggest adding another column introducing the raw materials according to the INCI name, so as to illustrate the formulation that was studied. Alternatively, I suggest presenting in one column the INCI composition of the base product and in another column the INCI composition after the introduction of substitutes. Then the reader will be able to immediately compare the changes. Meanwhile, move the functions to the description of ingredients with trade name and manufacturer.

5. Subsection 2.2. Methods should be divided into specific test methods. The text is lite and inconvenient to search for a specific research method.

6. Lines 228, 229. As I continue reading your article in section 3.1 I learn about more formulations. You have done a lot of work, just hard to verify it against the starting recipe. Maybe you should add a table with INCI composition so that you can compare formulations against each other and understand the F1 Z, F1 M, etc. designations.

7. Lines 233-235. Please check the correctness of the interpretation "On the contrary, the samples formulated with the inorganic texturizers S and H (F1 S and F1 H) were characterized by higher values of firmness, consistency, cohesiveness and adhesiveness, and lower values of stringiness" If the cohesiveness and adhesiveness of F1H in red have the lowest (negative) values among the samples tested then why do you think that "were characterized by higher values". Please check the interpretation in sections 3.2 and 3.3.

8. Lines 235-236. On what basis was this formulation quoted. Please either introduce the research results relating to this formulation or introduce the references where these research results supporting this statement are found.

9. Line 247. "Inorganic texturizers (G ...)" G is missing from the charts.

10. Line 249. Sentence should begin with a capital letter.

11. Table 4, 7, 10. In the Texturizer column, please enter the INCI names of the raw materials used instead of the designations.

12. Table 4, 7, 10. Please correct the unit from "Pa.s" to "Pa·s".

13. Line 263. What is the literature reference [32] in this task, paragraph. Analyze your research results with the literature reference [32]. If there are similar, important to the authors coincidental, relevant data in this work, please explain cite their work in two sentences.

14. Line 266. The sentence should begin with a capital letter.

15. Line 268. Delete F1.

16. Lines 269-289 - I repeat my request for the F1Z recipe. Once again you are adding variables to the F1 starting recipe. This is necessary so that the reader can clearly interpret the results. You have introduced so many variables that, unfortunately, we do not know what can be compared with what. You need to clearly indicate the base (formula, INCI raw material and its concentration).

17) Table 5. Why didn't you do the tests, according to the scheme, F1Zr0.75?

18. Table 5. In the line for F1Z t075 k01, you mistakenly entered 0.2 k % w/w.

19. Line 312. The sentence should be started with a capital letter.

20. Line 325-326. For easier understanding of the content, I suggest leaving the original designation. Apply to the rest of chapters 3.2 and 3.3.

21. Lines 345,347. The sentence should be started with a capital letter.

22. Lines 350-354. Another designation F1 R has been introduced. Please indicate which formulation this is, with which original designation? Since there are a lot of designations I think it is unnecessary to introduce more designations. Apply in the other chapters 3.2 and 3.3.

23. Lines 369-374. Please present the results for the interpretation presented in the form of a table or graph.

24. Lines 396, 407, 473, 492, 583. The sentence should be started with a capital letter.

25. Table 8. Please correct "sample name F1Zr".

26. Table 8. The selection of concentrations is puzzling. On what basis were the concentrations of each raw material determined?

27. Figure 11. Why does this chapter present such a broad visualization of the results compared to chapter 3.1 figure 5 or chapter 3.3 figure 16?

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

My opinion is that once the proposed modifications have been corrected, the manuscript is ready to publish in this magazine.

Reviewer 3 Report

Accept in present form