Production of Bovine Collagen Hydrolysate with Antioxidant Activity; Optimized by Response Surface Methodology

Round 1

Reviewer 1 Report

The major aim of this study is to optimize condition for antioxidation activities of gelatin hydrolysate. So, it's worth producing functional food. However, this manuscript have to be improved as listed below. 

1. Significance of each independent variables and other related data analysis for proposal of polynominal model should be described in "Results" section with essential data.

2. There are mistakes for manuscript preparation. (e.g. confusing "foods" and "proteins", no proper verb  [L52-L54], no Figures 1E and 1F [L158] etc.).

3. Products (gelatin peptides) should be (partly) characterized and discussed because "there is no evidence to produce appropriate degraded products" and "antioxidative activities of each proteolytic fragments varied in ref. 12".

Author Response

Dear Reviewer 1

Thank you very much for your valuable comments. All revisions have been considered and addressed precisely throughout the manuscript.

1. The significance of independent variables and related data analysis for the proposal of the second-degree fractional polynomial model are addressed and described in the "Results" section and highlighted in the manuscript.
2. All of these mistakes have been revised and highlighted throughout the manuscript.
3. The proteolysis index of the treatments was measured to confirm the degradation process of the protein sources; however, these data were not included in the model. This statement is added and highlighted in the text.

Author Response File: Author Response.doc

Reviewer 2 Report

The manuscript entitled “Production of bovine collagen hydrolysate with antioxidant activity; optimized by response surface methodology” by Babak Pakbin et al. described a model using RSM to describe and optimize conditions of enzymatic hydrolysis of bovine gelatin by trypsin to produce protein hydrolysate with antioxidant activity. The manuscript may be of general interest to the researchers of this field, but the manuscript lacks some information that the author should consider and incorporate in the present form of the manuscript. Here are a few concerns that need to be addressed in the present form of the manuscript.

 1.      The abstract should be corrected. The abstract follows the style of structured abstracts, but should be without headings. Therefore, the words “Background:”, “Method:”, “Result and Discussion:”, “Conclusion:” should be deleted.

2.      Introduction is poor for references.

3.    The positive control (reference drug) is absent in the study of antioxidant activity. It is difficult to estimate the level of antioxidant properties of the hydrolyzed gelatin solutions without comparison with a positive control.

4.      It is not clear from the text whether the authors tested the optimized conditions (35.3 °C, pH 8.0, E/S ratio at 2.5 after 2 h hydrolysis) obtained by RSM in a real experiment.

Author Response

Dear Reviewer 2

Thank you very much for your valuable comments they were very useful and practical to improve the quality of this research. All revisions have been considered and addressed precisely throughout the manuscript.

1. The abstract structure is corrected and highlighted in the manuscript.
2. References in the background section of the manuscript are developed, improved and highlighted in the references section.
3. The positive control was used in this study (Gallic acid). This statement is added and highlighted in the manuscript.
4. The optimized conditions were tested and the obtained results significantly (P < 0.05) confirmed the results released from the optimized conditions by the model. This statement is added and highlighted in the text.

Author Response File: Author Response.doc

Round 2

Reviewer 1 Report

It seems that authors improved manuscript, but it was not responsed to the reviewer's comments.

1. "milk ... gelatin and plant-based proteins are obtained from rice ...(all plants)... mushrooms etc." (L51-L52) ?

2. Part of results in later part of "2.2. Optimization and modeling of enzymatic hydrolysis process by response surface methodology" must be described in "Results", because these statements are "Results". Manuscript should be logically prepared.

3. Regarding author response, ”The proteolysis index of the treatments was measured to confirm the degradation process of the protein sources; however, these data were not included in the model.”, there is no evidence in this manuscript. 

Author Response

Dear Reviewer,

1. This sentence was incorrect and removed from the text.
2. This part is transmitted completely into the results section.
3. The proteolysis index of the treatments was randomly evaluated to just confirm the proteolysis reaction and was not included in the results, optimization and modelling processes. Consequently, the data regarding proteolysis is not mentioned in the text; however, they can be available via an official request from the corresponding author. The statement has been added to the Data availability section.

Author Response File: Author Response.pdf

Reviewer 2 Report

Dear colleagues,

many thanks for your respond to the suggestions from my side. I agree with your answers. 

Wishing you all the best in future studies! 

Author Response

Dear Reviewer,

Thank you very much.

Author Response File: Author Response.doc