UV-Curable Silicone-Modified Polyurethane Acrylates for Food Freshness Monitoring
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsAuthors talk about the UV–Curable pH–Sensitive Silicone Modified Polyurethane–Acrylates with Covalent–Grafted Neutral Red Groups for Monitoring Freshness of Shrimp and Pork. It is a good research and gives more insights into a UV cured application. Following are my suggestions and comments.
1. First, the title is long, how about a little more crisp one, example: UV-curable silicone modified PU acrylates as a food freshness monitor system. Maybe?
2. The system is uv cured, but there is no mention of any UV in the generic introduction., consider citing review articles. Example: https://doi.org/10.3390/jcs7120513
3. Figure 1 needs improvement in terms of showing what the arrows corresponds to, in terms of wave numbers and/or structures.
Author Response
Reviewer 1
Comments 1:
First, the title is long, how about a little more crisp one, example: UV-curable silicone modified PU acrylates as a food freshness monitor system. Maybe?
Response:
Thank the reviewer very much for the professional comments. According to the good comments and the title was modified to be “UV–Curable Silicone Modified Polyurethane– Acrylates for Food Freshness Monitoring”.
Comments 2:
The system is uv cured, but there is no mention of any UV in the generic introduction., consider citing review articles. Example: https://doi.org/10.3390/jcs7120513
Response:
We thank the reviewer a lot for the careful review. According to the good comments, the sentence “UV–cured technology gained much attention in coating industry due to the merits of high efficient, environmentally friendly, energy–saving[21]” was added in the section of introduction and the paper “https://doi.org/10.3390/jcs7120513” was added as reference 21 in the reversed manuscript.
Comments 3:
Figure 1 needs improvement in terms of showing what the arrows corresponds to, in terms of wave numbers and/or structures.
Response:
We appreciate the reviewer for the careful review. According to the good comments, the Fig. 1 was corrected as following:
Fig. 1 FT–IR spectrum of NR–PUA–3
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsDear Authors,
Overall, this article is very interesting and timely. It also raises, in my opinion, an interesting topic. However, I have a few important comments on the article.
Detailed comments below:
Introduction: This introduction does not exhaust the topics covered. Intelligent packaging has been used for many years. You will definitely find more information on this subject.
There is also a lack of a well-defined goal of scientific research. In this type of articles it is necessary.
Line 126: Was the appropriate program installed on the mobile phone? Please also provide your phone model and installed system.
Line 210:Descriptions should be made precisely. What does "works pretty well" mean? or "relatively good?". Whether the results obtained are close or far from expected. Compare the results with other studies.
Line 216: In what direction did the color change. Perhaps it would be beneficial to check it with a colorimeter (if possible, of course).
In my opinion, the discussion of the results is done a bit poorly. You should compare your results more often to the research of other authors. Also, whether your results are close or far from expected.
Conclusions: Line 254: Please describe the prospects for further development of intelligent packaging. Write a more forward-looking proposal.
Author Response
Reviewer 2
Comments 1:
Introduction: This introduction does not exhaust the topics covered. Intelligent packaging has been used for many years. You will definitely find more information on this subject.
Response:
Thank the reviewer very much for the professional and scientific comments. According to the good comments, the sentences “Recently, Sangeetha et al prepared an intelligent packaging materials from coconut husk-lignin derived carbon dots and carrageenan[8]. Yue et al prepared an intelligent packaging films with antibacterial performance by cellulose fibers, cellulose nanofibers, ZnO nanoparticles and polydiacetylene[9]. Ronte et al developed intelligent packaging material using chitosan grafted with phenol red to monitor shrimp freshness by pH change[10]” were added in the first paragraph of the introduction section.
Comments 2:
There is also a lack of a well-defined goal of scientific research. In this type of articles it is necessary.
Response:
Many thanks to the reviewer for the scientific comments. According to the comments, the first sentence of abstract “UV–curable silicone modified materials for monitoring freshness of some high protein food such as shrimp and pork were prepared from polyurethane–acrylates with covalent–grafted neutral red groups and thiol silicone resin. ” was improved to be “Intelligent materials for monitoring the condition of the packaged food or its surrounding are highly desired to ensure the food safety. In this paper, UV–curable silicone modified materials for monitoring freshness of some high protein food such as shrimp and pork were prepared from polyurethane–acrylates with covalent–grafted neutral red groups and thiol silicone resin.”
Comments 3:
Line 126: Was the appropriate program installed on the mobile phone? Please also provide your phone model and installed system.
Response:
We thank the reviewer a lot for the good comments. In the section “2.4. Characterization”, the sentence “The color variation was recorded by Na He using a mobile phone after the coatings on the glass slides were immersed in the aqueous with different pH values for about 20 min.” was improved to be “The color variation was recorded by Na He using a mobile phone (iPhone XS Max) after the coatings on the glass slides were immersed in the aqueous with different pH values for about 20 min”.
Comments 4:
Line 210:Descriptions should be made precisely. What does "works pretty well" mean? or "relatively good?". Whether the results obtained are close or far from expected. Compare the results with other studies.
Response:
Thank the reviewer very much for the careful review. We have check the manuscript and “relatively good” was modified to be “longtime”. There is no “"works pretty well"” in the manuscript. According to the scientific comments, the sentences “The pH–sensitive films prepared by Yue et al exhibited a color change after 30 min of exposure to ammonia with concentrations>=0.1 M[9]. Similarly, the intelligent pH–sensitive indicator films reported by Khanjanzadeh et al. [20] also changed from red to yellow after 30 min of exposure to ammonia vapor. Therefore, the UV–coatings exhibited quite sensitive pH variation performance and longtime color stability.” were added in the section of 3.2.3 The pH–sensitive property.
Comments 5:
Line 216: In what direction did the color change. Perhaps it would be beneficial to check it with a colorimeter (if possible, of course).
Response:
Thank the reviewer very much for the careful review. In aqueous with different pH values in the range of 2–12, it can be observed that the color of the UV–coatings changed gradually from deep red to yellowish–brown. Due to the lack of experimental equipment, we can not check it with a colorimeter.
Comments 6:
In my opinion, the discussion of the results is done a bit poorly. You should compare your results more often to the research of other authors. Also, whether your results are close or far from expected.
Response:
Thank the reviewer very much for the careful review and scientific comments. According to the scientific comments, the sentences “The pH–sensitive films prepared by Yue et al exhibited a color change after 30 min of exposure to ammonia with concentrations>=0.1 M[9]. Similarly, the intelligent pH–sensitive indicator films reported by Khanjanzadeh et al. [20] also changed from red to yellow after 30 min of exposure to ammonia vapor. Therefore, the UV–coatings exhibited quite sensitive pH variation performance and longtime color stability.” were added in the section of 3.2.3 The pH–sensitive property.
Comments 7:
Conclusions: Line 254: Please describe the prospects for further development of intelligent packaging. Write a more forward-looking proposal.
Response:
Thank the reviewer very much for the scientific comments. According to the scientific comments, “The UV–curable silicone modified pH–sensitive intelligent materials have potential application in monitoring freshness of some high protein food such as shrimp and pork.” was added in the section of conclusions.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsReview: “UV-Curable pH-Sensitive Silicone Modified Polyurethane-Acrylates with Covalent-Grafted Neutral Red Groups for Monitoring Freshness of Shrimp and Pork”
The authors' work presents a novel study on the changes associated with the color stability of coatings, a potentially significant development that could be used as intelligent pH-sensitive systems.
Keywords: Look for other keywords for the work since some are repetitive with the title of the research
The introduction could benefit from a clearer explanation of how a silicone coating would monitor the freshness of shrimp and pork.
What are the advances regarding pH-sensitive intelligent coatings?
highlight it in the preference introduction.
The authors present the structures of the polyurethane-acrylates used; however, they do not show an experimental design that visualizes the effect of the studied variables. They give only one example in the methodological writing of point 2.2.
Properly mention reference 19 and reference 18.
The table results do not show the statistical differences in the SD values.
The authors did not measure the color changes with a colorimeter to correlate the visual appearance with a measurement.
The images are unclear and do not show a statistical analysis of color changes.
In general, the proposal for coating intelligent packaging is perfect. However, the results lack support since some are only classified by hardness by visual color changes, and there is no scale for the analysis of slight differences due to the effect of pH, justify.
Author Response
Reviewer 3
Comments 1:
Keywords: Look for other keywords for the work since some are repetitive with the title of the research
Response:
Thank the reviewer very much for the scientific comments. According to the scientific comments, the keywords were modified from “pH–sensitive; high protein food; UV–curable; silicone modified materials” to be “pH–sensitive intelligent materials; food freshness monitoring; UV–curable; silicone modified materials”.
Comments 2:
The introduction could benefit from a clearer explanation of how a silicone coating would monitor the freshness of shrimp and pork.
Response:
Thank the reviewer very much for the scientific comments. pH change of the food attributed to amino acids and glucose metabolization was one of important and effective parameters for identifying food spoilage [11]. Neutral red (NR), a easy available water soluble pH–sensitive dye in the pH value of 4–6 with relative low toxicity, has been widely used [19]. Khanjanzadeh et al. [20] developed pH–sensitive films with a visible color variation at pH value of 2–10 by covalent bonding NR onto cellulose nanofibrils. This work revealed that NR is a good candidate to covalent–bonded onto polymer matrix to develop pH–sensitive intelligent materials.
Comments 3:
What are the advances regarding pH-sensitive intelligent coatings? highlight it in the preference introduction.
Response:
Thank the reviewer very much for the scientific comments and the advances regarding pH-sensitive intelligent materials described in introduction section as following:
Recently, Sangeetha et al prepared an intelligent packaging materials from coconut husk-lignin derived carbon dots and carrageenan[8]. Yue et al prepared an intelligent packaging films with antibacterial performance by cellulose fibers, cellulose nanofibers, ZnO nanoparticles and polydiacetylene[9]. Ronte et al developed intelligent packaging material using chitosan grafted with phenol red to monitor shrimp freshness by pH change[10]. pH change of the food attributed to amino acids and glucose metabolization was one of important and effective parameters for identifying food spoilage [11]. Low molecular synthetic pH indicators are not suitable for monitoring the food spoilage due to their toxic, carcinogenic, and mutagenic properties. Natural dyes such as anthocyanins, curcumin, alizarin, and betalains with safety and non–toxicity, renewability, are ideal sources of pH indicator materials [12–14]. However, the poor stability and insensitivity to minor changes in pH for natural pH indicators exposed to different environmental conditions seriously limit their applications [15,16].
To reduce the toxicity and improve the stability of pH–sensitive intelligent materials, covalent–bonding pH–indicators groups onto polymer matrix is a reliable strategy because the release probability of the dyes is greatly reduced. For example, a membrane with a visibly color change at different pH conditions of 2–12 was developed by immobilizing pH–sensitive dyes onto ethyl cellulose nanofibers, which exhibited a good stability up to 7 days at room temperature [17]. A pH–sensitive material for monitoring the freshness of pork for 12 days was also fabricated by covalent–grafting oregano essential oil and black rice bran anthocyanin onto the chitosan matrix [18]. Neutral red (NR), a easy available water soluble pH–sensitive dye in the pH value of 4–6 with relative low toxicity, has been widely used [19]. Khanjanzadeh et al. [20] developed pH–sensitive films with a visible color variation at pH value of 2–10 by covalent bonding NR onto cellulose nanofibrils. This work revealed that NR is a good candidate to covalent–bonded onto polymer matrix to develop pH–sensitive intelligent materials.
Comments 4:
The authors present the structures of the polyurethane-acrylates used; however, they do not show an experimental design that visualizes the effect of the studied variables. They give only one example in the methodological writing of point 2.2.
Response:
Thank the reviewer very much for the scientific comments. The feed ratios for preparation PUAs were list in Table S1.
Comments 5:
Properly mention reference 19 and reference 18.
Response:
Thank the reviewer very much for the scientific comments. According to the scientific comments, the sentences “The pH–sensitive films prepared by Yue et al exhibited a color change after 30 min of exposure to ammonia with concentrations>=0.1 M[9]. Similarly, the intelligent pH–sensitive indicator films reported by Khanjanzadeh et al. [20] also changed from red to yellow after 30 min of exposure to ammonia vapor. Therefore, the UV–coatings exhibited quite sensitive pH variation performance and longtime color stability.” were added in the section of 3.2.3 The pH–sensitive property.
Comments 6:
The table results do not show the statistical differences in the SD values.
Response:
Thank the reviewer very much for the scientific comments. Actually, though the table results do not show the statistical differences in the SD values, it reveled the trend of cross-linking density.
Comments 7:
The authors did not measure the color changes with a colorimeter to correlate the visual appearance with a measurement.
Response:
Thank the reviewer very much for the carefully review and scientific comments. Due to the lack of experimental equipment, we can not check it with a colorimeter.
Comments 8:
The images are unclear and do not show a statistical analysis of color changes. In general, the proposal for coating intelligent packaging is perfect. However, the results lack support since some are only classified by hardness by visual color changes, and there is no scale for the analysis of slight differences due to the effect of pH, justify.
Response:
Thank the reviewer very much for the carefully review. The UV–curable materials exhibited visible pH–sensitive performance and there is no scale for the analysis of slight differences.
Author Response File: Author Response.pdf
Round 2
Reviewer 3 Report
Comments and Suggestions for AuthorsNo comments
