Addition of Trans-Resveratrol-Loaded, Highly Concentrated Double Emulsion to Moisturizing Cream: Effect on Physicochemical Properties

Round 1

Reviewer 1 Report

Ref. No.: colloids-1984272

Manuscript: Addition of Trans-Resveratrol-Loaded Highly Concentrated Double Emulsion to moisturizing cream: Effect on Physico-chemical Properties

Journal: Colloids and Interfaces  

This work investigated the preparation and characterization of encapsulating resveratrol in concentrated water-in-oil-in-water double emulsions. Some comments are as follows:

1.      Line 30 “Producing a cream with a resveratrol concentration up to 0,0042 mg/g”??? A wrong expression.

2.      Lines 38-40 “its great instability” It should be specified about the instability. Moreover, this sentence should be provided by a reference, including its solubility.

3.      Introduction: There are too many paragraphs in this section; the authors need to be more focused.

4.      The emulsion should be introduced more, including the types of stabilizer, the types of emulsion. The novelty should be strengthened more. Furthermore, the main research content of this study need to be introduced.

5.      Line 103-107 Too many paragraphs.

6.      Line 134 “1/4, 1/3 and 1/2 emulsion” Weight ratio or volume ratio.

7.      Figure 1: The droplet size distribution of emulsion in cream 1/2, 1/3 is strange, the authors should explain more.

8.      Some figures should be reorganized, such as Fig.3, Fig.4.

9.      Line 287 “Texturometry results are shown in Error! Reference source not found..”???

10.   Trans-Resveratrol-Loaded emulsion, the stability, loading, and bioaccessibility of Trans-Resveratrol is recommended to study.

Author Response

We would like to thank the reviewers for their comments on our manuscript entitled Addition of Trans-Resveratrol-Loaded Highly Concentrated Double Emulsion to moisturizing cream: Effect on Physicochemical Properties (Ref.: colloids-1984272). After careful revision and taking into consideration these comments, changes in the manuscript have been made, and are highlighted in the revised manuscript and in blue text. These changes are discussed in the following paragraphs.

Reviewer 1

1. Line 30 “Producing a cream with a resveratrol concentration up to 0,0042 mg/g”??? A wrong expression.

The sentence has been revised in the abstract of the revised version of the manuscript.

2. Lines 38-40 “its great instability” It should be specified about the instability. Moreover, this sentence should be provided by a reference, including its solubility.

Authors agree with the referee’s comment. Several references [1–5] have been included on the revised version of the manuscript, related to its instability and poor solubility.

3. Introduction: There are too many paragraphs in this section; the authors need to be more focused.

Thank you for your suggestion, introduction section has been revised and summarized in the manuscript.

4. The emulsion should be introduced more, including the types of stabilizer, the types of emulsion. The novelty should be strengthened more. Furthermore, the main research content of this study need to be introduced.

Authors appreciate your recommendation, so the emulsion information related to its formulation and the main goal of the manuscript have been included in the revised version of the manuscript.

5. Line 103-107 Too many paragraphs.

It has been revised in the revised version of the manuscript.

6. Line 134 “1/4, 1/3 and 1/2 emulsion” Weight ratio or volume ratio.

The ratio of the mixture of cream and emulsion is in terms of weight. We have included this information on the material methods section of the revised version of the manuscript.

7. Figure 1: The droplet size distribution of emulsion in cream 1/2, 1/3 is strange, the authors should explain more.

Detailed analysis data has been included in the revised version of the manuscript. Moreover, the double emulsion particle size distribution has been included so the discussion could be strength.

8. Some figures should be reorganized, such as Fig.3, Fig.4.

Figures number has been revised in the revised version of the manuscript.

9. Line 287 “Texturometry results are shown in Error! Reference source not found..”???

Authors apologize the mistake, it has been corrected.

10. Trans-Resveratrol-Loaded emulsion, the stability, loading, and bioaccessibility of Trans-Resveratrol is recommended to study.

Even the formulation and volumetric ratios of the double emulsion were optimized in a previous work. Authors agree that the incorporation of the double emulsion characterization as a control can enhance the discussion of the present article and hence it has been included in the revised version of the manuscript.

The bioaccessibility of resveratrol when it incorporated to other food matrix systems has been studied in previous works [6].

References

1. Robinson, K.; Mock, C.; Liang, D. Pre-Formulation Studies of Resveratrol. Drug Dev. Ind. Pharm. 2015, 41, 1464–1469, doi:10.3109/03639045.2014.958753.
2. Wu, Y.; He, D.; Zong, M.; Wu, H.; Li, L.; Zhang, X.; Xing, X.; Li, B. Improvement in the Stability and Bioavailability of Trans-Resveratrol with Hydrolyzed Wheat Starch Complexation: A Theoretical and Experimental Study. Food Struct. 2022, 32, 100267, doi:10.1016/j.foostr.2022.100267.
3. Lafarge, E.; Villette, S.; Cario-André, M.; Lecomte, S.; Faure, C. Transdermal Diffusion of Resveratrol by Multilamellar Liposomes: Effect of Encapsulation on Its Stability. J. Drug Deliv. Sci. Technol. 2022, 76, 103742, doi:https://doi.org/10.1016/j.jddst.2022.103742.
4. Sessa, M.; Tsao, R.; Liu, R.; Ferrari, G.; Donsì, F. Evaluation of the Stability and Antioxidant Activity of Nanoencapsulated Resveratrol during in Vitro Digestion. J. Agric. Food Chem. 2011, 59, 12352–12360, doi:10.1021/jf2031346.
5. Liu, Y.; Fan, Y.; Gao, L.; Zhang, Y.; Yi, J. Enhanced PH and Thermal Stability, Solubility and Antioxidant Activity of Resveratrol by Nanocomplexation with α-Lactalbumin. Food Funct. 2018, 9, 4781–4790, doi:10.1039/c8fo01172a.
6. Díaz-Ruiz, R.; Laca, A.; Sánchez, M.; Fernández, M.R.; Matos, M.; Gutiérrez, G. Addition of Trans-Resveratrol-Loaded Highly Concentrated Double Emulsion to Yoghurts: Effect on Physicochemical Properties. Int. J. Mol. Sci. 2022, 23, doi:10.3390/ijms23010085.

Reviewer 2 Report

The article “Addition of Trans-Resveratrol-Loaded Highly Concentrated  Double Emulsion to moisturizing cream: Effect on Physico-chemical Properties” was submitted to Colloids and Interfaces for the special issue “Recent Advances in Emulsions and Applications”.

General observations:

In this manuscript, the authors investigated the effect produced by adding a double emulsion with optimal formulation to a commercial cream for cosmetic applications. The double emulsion is used to encapsulate Resveratrol to prevent it from irreversibly transformation due to exposure to light. The effect of the addition of the double emulsion is studied in terms of analyzing droplet size distribution, morphology, stability, rheology of the commercial cream

The English language and style are correct, only minor spelling are required.

The article is well documented, there are many references and the ‘Materials and Methods’ section is well detailed. However, the introduction is a bit confusing and some parts of the "Results and Discussion" section need more detail and elaboration. Data from the double emulsion as a second control is missing to better understand the results obtained when mixing with the commercial cream. Adding these data will allow a better understanding of the results and the authors will be able to better interpret the differences and similarities.

Therefore, for all of the above reasons and my many comments that follow, I cannot recommend publication of this work in Colloids and Interfaces before a major revision.

Observations and comments:

1. Introduction :

Page 1 line 35 to page 2 line68 : The ideas presented in these paragraphs are disordered, with the authors talking about the benefits of the RSV and then about its transformation and then back to the benefits … It is confusing, the authors should first focus on the benefits of RSV, then talk about its photosensitivity and finally focus on the encapsulation process.

2. Material and Methods :

Page 3 line 105 : What is the CMC of the PGPR? Did you measure it and how? Is the concentration higher than the CMC? Is this concentration sufficient in terms of the interface created during the emulsion process?

Page 3 line 119 : What is the CMC of the Tween 20? Did you measure it and how? Is the concentration higher than the CMC? Is this concentration sufficient in terms of the interface created during the emulsion process?

Page 4 line 143 to 148 : Did you use Mie theory or Fraunhoffer approximation to determine the size? If you used Mie theory, can you add the refractive indices chosen for the calculations.

Page 4 line 164 : “relative to standards (suspension of monodisperse spheres and silicone oil)”. I did not understand if you compare your results to standards or if the device is calibrated with standards.

Page 4 line 175 : please define “CR”.

3. Results and Discussion :

Figure 1 : the size distribution of the double emulsion is missing in order to have a better idea of the size change when mixing the 2. The representation of the graph can be improved by limiting the size range from 0.05 to 500 microns.

Page 5 line 203 to page 6 line 222 : In my opinion, it is not always easy to interpret size distributions when mixing 2 dispersions with a very different number of drops. Do you have an idea of the number of drops of the commercial cream compared to the emulsion? what is the volume fraction of dispersed phase of the commercial cream? If there are few drops in the commercial cream compared to the emulsion, as soon as we mix the 2, we will no longer see the presence of the drops of the commercial cream in the size distribution.

Page 6 line 229 to 234 : It is obvious from the pictures that the commercial cream has a very different structure than the cream/emulsion mixture. However, a picture of the emulsion alone is missing to get an idea of the change according to the proportion of the 2. Moreover, the images do not allow to really see the difference in size between the 4 systems because of the high concentration. We observe much larger elements for the commercial cream alone while the measured sizes are smaller.

Figure 3 : Why didn't you use the TSI parameter to better show the instability of the dispersions? In my opinion, the stability of the double emulsion alone is missing.

In parts 3.1 and 3.2, the data for the double emulsion alone is clearly missing to have a better idea of the interpretation of the mixing : whether the size change is due more to coalescence or to a population difference ?

Page 7 line 250 to 253 : “it is remarkable that the commercial cream and the mixture with a quarter of emulsion flow curves were almost identical”. When looking at Figure 4, it is not at all obvious that the blue and red curves are almost identical. Could you comment this point?

Figure 4 : In the legend, “commercial cream (control)” better than just “control”. I also suggest to add the curve of the double emulsion alone.

Table 1 page 8 : add double emulsion data.

Page 8 line 262 to 265 : This observation confirms the behavior observed previously in Figure 1. It seems that Emulsion cream 1/4 has the behavior of the double emulsion + commercial cream, the sizes and their rheological properties seem to add up whereas when the concentration of added emulsion increases the effect is the opposite because the structure of the cream changes strongly. The authors should compare and comment more on their results.

Page 8 line 267 : “Figure 5” not “Figure 4”.

Page 9 line 299 to 301 : Can you give a reference or data explaining this. From what changes in values does the consumer come to feel a difference?

Page 9 line 306 : “the greater the amount of emulsion”.

Author Response

We would like to thank the reviewers for their comments on our manuscript entitled Addition of Trans-Resveratrol-Loaded Highly Concentrated Double Emulsion to moisturizing cream: Effect on Physicochemical Properties (Ref.: colloids-1984272). After careful revision and taking into consideration these comments, changes in the manuscript have been made, and are highlighted in the revised manuscript and in blue text. These changes are discussed in the following paragraphs.

Reviewer 2

General observations:

The article is well documented, there are many references and the ‘Materials and Methods’ section is well detailed. However, the introduction is a bit confusing and some parts of the "Results and Discussion" section need more detail and elaboration. Data from the double emulsion as a second control is missing to better understand the results obtained when mixing with the commercial cream. Adding these data will allow a better understanding of the results and the authors will be able to better interpret the differences and similarities.

However, authors agree that the inclusion as a control of the emulsion will help to understand what is taking place when mixed systems are analyzed and hence individual characterization of the selected emulsion was included in the revised version of the manuscript as a control.

Observations and comments:

1. Introduction :

Page 1 line 35 to page 2 line68 : The ideas presented in these paragraphs are disordered, with the authors talking about the benefits of the RSV and then about its transformation and then back to the benefits … It is confusing, the authors should first focus on the benefits of RSV, then talk about its photosensitivity and finally focus on the encapsulation process.

Thank you for your recommendation, introduction section has been reorganized.

2. Material and Methods :

Page 3 line 105 : What is the CMC of the PGPR? Did you measure it and how? Is the concentration higher than the CMC? Is this concentration sufficient in terms of the interface created during the emulsion process?

The PGPR CMC was not measured in this study since, in previous works developed by the authors, various formulations were studied (W₁/O concentrations, double emulsion concentration, presence of carboxymethylcellulose, use of different surfactants in different ratios,...) in order to obtain the double emulsion formulation with the maximum concentration of resveratrol that its colloidal stability allowed [7,8][7]. This fact was obtained with the concentrations of PGPR and Tween 20 used in the present study with internal ratio 30/70 and external emulsion ratio 80/20. Hence, this was the selected formulation in the present study. This information has been included in the material and methods section of the revised version of the manuscript.

Page 3 line 119 : What is the CMC of the Tween 20? Did you measure it and how? Is the concentration higher than the CMC? Is this concentration sufficient in terms of the interface created during the emulsion process?

Tween 20 is a surfactant with quite low CMC value 0.06 mg/mL according to other authors [9,10]. However, it is known that this value is typically reduced by the presence of salt as it is indicated in some previous studies [11].

In the present work a concentration of 20 mg/mL was used in the aqueous phase, that ensure that the CMC value was arise. However, it is true that the large internal phase ratio involves the presence of high interfacial phase to cover. No experiments regarding surfactant coverage were made in the present study. However precious research works indicate that the concentration of surfactant use is enough to ensure double emulsion stability [7,12]. This information has been included in the revised version of the manuscript.

Page 4 line 143 to 148 : Did you use Mie theory or Fraunhoffer approximation to determine the size? If you used Mie theory, can you add the refractive indices chosen for the calculations.

The Mastersizer is a laser diffraction-based system from Malvern Instruments that uses Mie theory to provide particle size measurement. We have included in the manuscript that the refractive index of the Miglyol 812 (1.54) was used for double emulsions droplet size measurements.

Page 4 line 164 : “relative to standards (suspension of monodisperse spheres and silicone oil)”. I did not understand if you compare your results to standards or if the device is calibrated with standards.

Turbiscan measurements, which are directly obtained from the instrument, are referenced to the mentioned standards.  

Page 4 line 175 : please define “CR”.

Sorry for the lack of clarity, we have specified in the manuscript that CR is the abbreviation of Control Rate.

3. Results and Discussion :

Figure 1 : the size distribution of the double emulsion is missing in order to have a better idea of the size change when mixing the 2. The representation of the graph can be improved by limiting the size range from 0.05 to 500 microns.

Thank you very much for your recommendation. Figure 1 has been adjusted and data related to the double emulsion it has been included.

Page 5 line 203 to page 6 line 222 : In my opinion, it is not always easy to interpret size distributions when mixing 2 dispersions with a very different number of drops. Do you have an idea of the number of drops of the commercial cream compared to the emulsion? what is the volume fraction of dispersed phase of the commercial cream? If there are few drops in the commercial cream compared to the emulsion, as soon as we mix the 2, we will no longer see the presence of the drops of the commercial cream in the size distribution.

The internal volume fraction of the commercial cream is not known, as well as its formulation. Authors agree with reviewer comment, to analyze particle size distribution of two mixed systems it is complicate. In the present case, it seems that the incorporation of 1/3 and 1/2 of emulsion on the final mixture, has a crucial impact on the final particle size distribution, being the size of the emulsion the predominant size. According to this, we can conclude that the internal fraction of the cream could be presumable less the internal fraction of the emulsion. Cream presents a viscous aspect, but probably is due to the presence of stabilizers and thickeners on the external aqueous phase. This information has been mentioned in the revised version of the manuscript.

Page 6 line 229 to 234 : It is obvious from the pictures that the commercial cream has a very different structure than the cream/emulsion mixture. However, a picture of the emulsion alone is missing to get an idea of the change according to the proportion of the 2. Moreover, the images do not allow to really see the difference in size between the 4 systems because of the high concentration. We observe much larger elements for the commercial cream alone while the measured sizes are smaller.

We have included the micrograph of the double emulsion alone that allow to confirm the existence of this type of emulsion and to verify the droplet size obtained with the Mastersizer. This confirms that the inclusion of double emulsion on the cream produces an interlaced between both systems, since it is more easily appreciate the presence of the dispersed phase droplets on systems individually. This observation has been included in the revised version of the manuscript.

Figure 3 : Why didn't you use the TSI parameter to better show the instability of the dispersions? In my opinion, the stability of the double emulsion alone is missing.

We have included the evolution of the backscattering of the double emulsion. We included this analysis of the Turbiscan instead of the TSI to be able to analyze the aging of the sample as a function of height, that is, to be able to determine if it is producing creming in the upper zone or sedimentation in the lower zone. In complex systems were clarification, creaming and coalesce or flocculation can occur at the same time. From our experience, the measurement of an overall parameter, as it is the case of TSI, can give a not accurate value, due to the compensation between instability phenomena occurring at the same time.

In parts 3.1 and 3.2, the data for the double emulsion alone is clearly missing to have a better idea of the interpretation of the mixing : whether the size change is due more to coalescence or to a population difference ?

The stability backsttering profile of the emulsion alone, as a control, has been included in the revised version of the manuscript. It can be observed that double emulsion presents a clarification on the bottom part of the cell, which is not appreciable when this emulsion was mixed with the commercial cream. Probably due to large viscosity of the sample, what increases the stability of the system versus clarification or creaming phenomena. However, especially in the case that ½ of emulsion was included on the commercial cream, it can be observed a change on the top part of the system indicating a instability process related to creaming probably due to drops coalesce what seems to be promoted by the interaction between both systems.

Page 7 line 250 to 253 : “it is remarkable that the commercial cream and the mixture with a quarter of emulsion flow curves were almost identical”. When looking at Figure 4, it is not at all obvious that the blue and red curves are almost identical. Could you comment this point?

Authors agree with referee comments. This has been revised and more complete analysis of the results found are discussed in the revised version of the manuscript. It is observed a decrease on the viscosity then the emulsion is present on the commercial cream. However, curve shape and fitting on Herschel-Bulkley model indicates a similar flow behavior for commercial cream and mixture with ¼ of double emulsion. While double emulsion alone and mixture with ½ of emulsion present more similar rheological behavior.

Figure 4 : In the legend, “commercial cream (control)” better than just “control”. I also suggest to add the curve of the double emulsion alone.

Rheological behaviour of emulsion control has been added. Moreover, legend has been modified in the revised version of the manuscript.

Table 1 page 8 : add double emulsion data.

We have included it in the revised version of the manuscript.

Page 8 line 262 to 265 : This observation confirms the behavior observed previously in Figure 1. It seems that Emulsion cream 1/4 has the behavior of the double emulsion + commercial cream, the sizes and their rheological properties seem to add up whereas when the concentration of added emulsion increases the effect is the opposite because the structure of the cream changes strongly. The authors should compare and comment more on their results.

In the revised version of the article, droplet size stability and viscosity measurements of the double emulsion were added as control. Results of both control systems, cream and double emulsion, has been compared with the three mixture studied.

Page 8 line 267 : “Figure 5” not “Figure 4”.

Figures number has been revised in this version of the manuscript.

Page 9 line 299 to 301 : Can you give a reference or data explaining this. From what changes in values does the consumer come to feel a difference?

We have not carried out a sensory analysis with expert. However, more precise information in included in the revised version of the manuscript including to references [13–15] were it can be indicate that hardness differences below 13% for the was not perceptible by fingertip. Moreover, the change perception of stickiness seems to be not significant for large number of population when it is lower than 6-8%. What indicates that even the addition of 1/4 of emulsion to the mixture has acceptable changes on hardness, the presence of double emulsion could produce on stickiness noticeable changes to the final cream.

Page 9 line 306 : “the greater the amount of emulsion”.

It has been corrected.

REFERENCES:

1. Robinson, K.; Mock, C.; Liang, D. Pre-Formulation Studies of Resveratrol. Drug Dev. Ind. Pharm. 2015, 41, 1464–1469, doi:10.3109/03639045.2014.958753.
2. Wu, Y.; He, D.; Zong, M.; Wu, H.; Li, L.; Zhang, X.; Xing, X.; Li, B. Improvement in the Stability and Bioavailability of Trans-Resveratrol with Hydrolyzed Wheat Starch Complexation: A Theoretical and Experimental Study. Food Struct. 2022, 32, 100267, doi:10.1016/j.foostr.2022.100267.
3. Lafarge, E.; Villette, S.; Cario-André, M.; Lecomte, S.; Faure, C. Transdermal Diffusion of Resveratrol by Multilamellar Liposomes: Effect of Encapsulation on Its Stability. J. Drug Deliv. Sci. Technol. 2022, 76, 103742, doi:https://doi.org/10.1016/j.jddst.2022.103742.
4. Sessa, M.; Tsao, R.; Liu, R.; Ferrari, G.; Donsì, F. Evaluation of the Stability and Antioxidant Activity of Nanoencapsulated Resveratrol during in Vitro Digestion. J. Agric. Food Chem. 2011, 59, 12352–12360, doi:10.1021/jf2031346.
5. Liu, Y.; Fan, Y.; Gao, L.; Zhang, Y.; Yi, J. Enhanced PH and Thermal Stability, Solubility and Antioxidant Activity of Resveratrol by Nanocomplexation with α-Lactalbumin. Food Funct. 2018, 9, 4781–4790, doi:10.1039/c8fo01172a.
6. Díaz-Ruiz, R.; Laca, A.; Sánchez, M.; Fernández, M.R.; Matos, M.; Gutiérrez, G. Addition of Trans-Resveratrol-Loaded Highly Concentrated Double Emulsion to Yoghurts: Effect on Physicochemical Properties. Int. J. Mol. Sci. 2022, 23, doi:10.3390/ijms23010085.
7. Díaz-Ruiz, R.; Martínez-Rey, L.; Laca, A.; Álvarez, J.R.; Gutiérrez, G.; Matos, M. Enhancing Trans-Resveratrol Loading Capacity by Forcing W1/O/W2 Emulsions up to Its Colloidal Stability Limit. Colloids Surfaces B Biointerfaces 2020, 193, 111130, doi:10.1016/j.colsurfb.2020.111130.
8. Matos, M.; Gutiérrez, G.; Martínez-Rey, L.; Iglesias, O.; Pazos, C. Encapsulation of Resveratrol Using Food-Grade Concentrated Double Emulsions : Emulsion Characterization and Rheological Behaviour. J. Food Eng. 2018, 226, 73–81, doi:10.1016/j.jfoodeng.2018.01.007.
9. Szymczyk, K.; Szaniawska, M.; Taraba, A. Micellar Parameters of Aqueous Solutions of Tween 20 and 60 at Different Temperatures: Volumetric and Viscometric Study. Colloids and Interfaces 2018, 2.
10. Mittal, K.L. Determination of CMC of Polysorbate 20 in Aqueous Solution by Surface Tension Method. J. Pharm. Sci. 1972, 61, 1334–1335, doi:https://doi.org/10.1002/jps.2600610842.
11. Miyagishi, S.; Okada, K.; Asakawa, T. Salt Effect on Critical Micelle Concentrations of Nonionic Surfactants, N-Acyl-N-Methylglucamides (MEGA-N). J. Colloid Interface Sci. 2001, 238, 91–95, doi:10.1006/jcis.2001.7503.
12. Matos, M.; Gutiérrez, G.; Coca, J.; Pazos, C. Preparation of Water-in-Oil-in-Water (W1/O/W2) Double Emulsions Containing Trans-Resveratrol. Colloids Surfaces A Physicochem. Eng. Asp. 2014, 442, 69–79, doi:10.1016/j.colsurfa.2013.05.065.
13. Aktar, T.; Chen, J.; Ettelaie, R.; Holmes, M. Tactile Sensitivity and Capability of Soft-Solid Texture Discrimination. J. Texture Stud. 2015, 46, 429–439, doi:https://doi.org/10.1111/jtxs.12142.
14. Yeon, J.; Kim, J.; Ryu, J.; Park, J.-Y.; Chung, S.-C.; Kim, S.-P. Human Brain Activity Related to the Tactile Perception of Stickiness. Front. Hum. Neurosci. 2017, 11, 8, doi:10.3389/fnhum.2017.00008.
15. Gilbert, L.; Savary, G.; Grisel, M.; Picard, C. Predicting Sensory Texture Properties of Cosmetic Emulsions by Physical Measurements. Chemom. Intell. Lab. Syst. 2013, 124, 21–31, doi:https://doi.org/10.1016/j.chemolab.2013.03.002.

Round 2

Reviewer 1 Report

Accept.

Author Response

Authors thank your  previous comments and final decision.

Reviewer 2 Report

I would like to thank the authors who took into consideration all my comments and remarks.

I recommend publication of this article in Colloids and Interfaces after the authors comment and address the following points:

Figure 1 : Can you comment on the fact that the Emulsion in cream 1/2 (purple) contains a larger volume of droplets than the double emulsion (red) for the main peak? While the 2 distributions have the same profile, a single peak and a more or less equal width. One could have expected the opposite behaviour.

3.2 Colloidal stability: This section could be a little more detailed. I recommend that the authors include the answers they gave me in the 1st review report.

Author Response

Figure 1 : Can you comment on the fact that the Emulsion in cream 1/2 (purple) contains a larger volume of droplets than the double emulsion (red) for the main peak? While the 2 distributions have the same profile, a single peak and a more or less equal width. One could have expected the opposite behaviour.

Authors agree that the opposite trend could be expected. Emulsion droplet size distribution present a wider peak than mixtures of 1/3 and 1/2 of emulsion on cream. It can be also observed that the presence of the smaller droplets (around 5 µm) are disappearing when the incorporation ratio of emulsion on the cream increases. This behaviour indicates a clear interaction of both systems, in which the emulsion droplets could be networking as a cream droplets flocculants producing larger agglomerates of drops which can be measured on laser instrument as a individual drops. This interaction can be also confirmed by micrographs from Figure 2 in which clear interaction of both systems are observed in mixtures. It is difficult to appreciate individual large drops on mixed systems as in the cases of plain emulsion or plain cream.

This information has been included in the revised version of the manuscript and highlighted in green.

This observation are included in the revised version of the manuscript.

3.2 Colloidal stability: This section could be a little more detailed. I recommend that the authors include the answers they gave me in the 1st review report.

More detailed discussion of the systems stability has been included in the revised version of the manuscript, including the information related to the 1^st review report.