Mathematical Modeling of Water-Soluble Astaxanthin Release from Binary Polysaccharide/Gelatin Blend Matrices

Round 1

Reviewer 1 Report

This is a nice publication, well prepared with care. There are only some small questions/additions/revisions that are needed. I believe that these are necessary and are as follows, in no particular order of importance:

• Keywords: The use of acronyms in keywords is not recommended.
• Line 32. “The” can be omitted.
• Line 54. Compared with what biopolymers? This statement is not correct and it is supported only by self-citations. Please check.
• Line 101-103: This sentence is confusing and needs revision. Please check.
• Figures 5 and 6 are too many and too small. I suggest reducing without loss of value, leaving only some representatives curves.
• Why the release study time was set to 32 hs and not longer?
• Film thickness should be reported.
• Total solubility of the films in water was measured? This would be interesting to compare the solubility and erosion of the different films.
• In the same way, it was concluded that “It suggests that this formulation applied on the high moisture food will maintain the main dose of the carotenoid on the surface”. But what about the migration of gelatin, polysaccharides and other film components? Overall migration, i.e., was measured? Also, are these films stable after 32 hs?
• Moreover, if these films are intended to be used as food packaging some basic characterization is missing. I.e. film thickness, moisture content, color, mechanical and barrier properties, etc. Have authors characterized the films or are planning to do in a future work?

Author Response

This is a nice publication, well prepared with care. There are only some small questions/additions/revisions that are needed. I believe that these are necessary and are as follows, in no particular order of importance:

• Keywords: The use of acronyms in keywords is not recommended.

It has been corrected.

 

• Line 32. “The” can be omitted.

It has been corrected.

 

• Line 54. Compared with what biopolymers? This statement is not correct and it is supported only by self-citations. Please check.

It has been corrected: “In general, gelatin (GEL), as a collagen derivative, forms more mechanically strong films compared to other biopolymers, such as cellulose derivatives, modified starches, gum Arabic (GAR), soy polysaccharides, and soy proteins [7,10]”.

 

• Line 101-103: This sentence is confusing and needs revision. Please check.

It has been corrected: “A constant amount of total solids (0.0125g/cm2) was placed on the trays in order to maintain film thickness”.

 

• Figures 5 and 6 are too many and too small. I suggest reducing without loss of value, leaving only some representatives curves.

The representative curves were presented in the corrected manuscript. Please see Fig. 5.

 

• Why the release study time was set to 32 hs and not longer?

The release tests were limited to 32 h because of a further progressive spoilage of film samples (the presence of a bad odour coming from the acceptor solution). It has been mentioned in the revised version of manuscript. Please see Section 2.4 and Conclusion.

 

• Film thickness should be reported.

The film thickness has been added. Please see Table 2. The data has been discussed. Please see Section 3.1.

 

• Total solubility of the films in water was measured? This would be interesting to compare the solubility and erosion of the different films.

The Reviver is right. However, the solubility behavior of the polisacharide75/gelatin25 films has been determined in our two previous works”:

• Edible films made from blends of gelatin and polysaccharide-based emulsifiers - A comparative study
• Release kinetics and antibacterial activity of potassium salts of iso-α-acids loaded into the films based on gelatin, carboxymethyl cellulose and their blends

This study is a part of project 2019/35/N/NZ9/01795 (https://projekty.ncn.gov.pl/index.php?projekt_id=466182).

 

 

• In the same way, it was concluded that “It suggests that this formulation applied on the high moisture food will maintain the main dose of the carotenoid on the surface”. But what about the migration of gelatin, polysaccharides and other film components? Overall migration, i.e., was measured? Also, are these films stable after 32 hs?

It was beyond the aim of our study to determine the overall migration of all film components. The conclusion has been corrected. The release tests were limited to 32 h because of a further progressive spoilage of film samples (the presence of a bad odour coming from the acceptor solution). It has been mentioned in the revised version of manuscript. Please see Section 2.4 and Conclusion.

 

• Moreover, if these films are intended to be used as food packaging some basic characterization is missing. I.e. film thickness, moisture content, color, mechanical and barrier properties, etc. Have authors characterized the films or are planning to do in a future work?

It was beyond the aim of this study to determine all functional properties of the films. This study is a part of project financially supported by the National Science Centre (Poland) under grant number 2019/35/N/NZ9/01795 (https://projekty.ncn.gov.pl/index.php?projekt_id=466182). The physicochemical (optical, barrier, mechanical) and antioxidant properties of the films, as well as the storage stability were determined and a separate manuscript is currently being prepared. It has been mentioned in the revised version of manuscript. Please see the Conclusion.

Author Response File: Author Response.docx

Reviewer 2 Report

Dear Colleagues,

I consider your paper "Mathematical modeling of water-soluble astaxanthin release from binary polysaccharide/gelatin blend matrices" is appropriate for being published, in present form, in Colloids and Interfaces.

 

Author Response

Thank you.

Reviewer 3 Report

This paper describes the fabrication of blend films incorporated with astaxanthin and their releasing behaviors. These matrices may provide potential candidates various applications. After necessary revision, I think this paper can be accepted for publication. Detailed comments are as follows:

1. Page 2, Line 94, the full name of DSM should be given.
2. Page 4, Line 145, and Figure 1, why use the CMC/Gel as the control?
3. 2B is the film casted from the aqueous solution, it is not the solution.
4. Page 3, Line 103, the full name of FFSs should be given.
5. Page 3, Line 107, the experimental conditions should be given here.
6. 5 and 6 contain too many figures, they are too small and hard to see the details.
7. The authors are advised to consider the practical application scenarios to decide the experimental conditions, such as the temperature. The question that can be asked here is why select 25 centigrade? Not 30 centigrade?

 

Author Response

This paper describes the fabrication of blend films incorporated with astaxanthin and their releasing behaviors. These matrices may provide potential candidates various applications. After necessary revision, I think this paper can be accepted for publication. Detailed comments are as follows:

Page 2, Line 94, the full name of DSM should be given.

The full name “DSM Nutritional Products” has been added. Since DSM Nutritional Products is an international company (https://www.dsm.com/corporate/about/businesses/dsm-nutritional-products.html), the country has been removed.

   

Page 4, Line 145, and Figure 1, why use the CMC/Gel as the control?

Please note that there are the four control films (AST 0%) prepared in this study. Their order is alphabetic.

 

2B is the film casted from the aqueous solution, it is not the solution.

Thank you for the Reviewer accurate observation. Fig. 2 consists series of photos that prove presence of starch granules in the AST formulation. The AST powder and aqueous solutions of AST were presented. Fig 2B presents the dehydrated AST solution. It has been mentioned in the revised manuscript.

 

Page 3, Line 103, the full name of FFSs should be given.

“FFSs” has been replaced with “film-forming solutions”.

 

Page 3, Line 107, the experimental conditions should be given here.

The information has been added. “SEM was used in order to visualize the surface of the films, dry AST powder, and 1% AST aqueous solution. After drying in a Polaron CPD 7501 critical point dryer (Quorum Technologies Ltd,  East  Sussex,  UK), the samples were sputter coated (Polaron SC7620, Quorum Technologies Ltd, East  Sussex,UK) with 20-30 nm layer of gold palla-dium (Au/Pd) and examined using LEO 1430 VP scanning electron microscope (LEO Electron Microscopy Ltd., Cambridge, UK) at following presets: accelerating voltage of 15 kV, aperture size: 30 μm, beam current 30 μm, signal: secondary electron detector, chamber pressure: 2.35e-003 Pa, working distance: 10-13 mm, image resolution: 2048 × 1576 pixel, scanning mode: pixel noise reduction. Additionally, the AST aqueous solution was examined with the Olympus MCKX53 light microscope (Olympus, Tokyo, Japan).The diameter of the objects was measured using AxioVision Rel 4.8 software (Carl Zeiss Microscopy GmbH, Göttingen”, Germany).

 

 5 and 6 contain too many figures, they are too small and hard to see the details.

According to the Reviewer 1 suggestion only representative curves were presented in the corrected manuscript. Please see Fig. 5.

 

The authors are advised to consider the practical application scenarios to decide the experimental conditions, such as the temperature. The question that can be asked here is why select 25 centigrade? Not 30 centigrade?

The Reviver is right, the AST release conditions should reflect the further food storage conditions as close as possible. The AST–supplemented films could be potentially used as packaging for cheese, nuts, red meat, surimi sticks, etc. Therefore, in our opinion, the release test should be conducted both at refrigerator temperatures (2°C to 8°C) and room temperature (the highest predictable contact temperature). We have determined the release of AST at 25^oC as the first temperature. The results showed that the release of AST from OSA/GEL carrier was very slow and incomplete. According to Commission Regulation (EU) 2016/1416 (amending and correcting Regulation (EU) No. 10/2011 on plastic materials and articles intended to come into contact with food) for contact times greater than 30 days (long term) at room temperature and below, the specimen could be tested under accelerated test conditions at elevated temperature (e.g. 30^oC). It is also worth mentioning that the film samples underwent progressive spoilage (the presence of a bad odour coming from the acceptor solution) during the test. Therefore, the accelerated test conditions at elevated temperature can be recommended, as suggested in Conclusion Section.