Investigating the Nano-Films Effect on Physical, Mechanical Properties, Chemical Changes, and Microbial Load Contamination of White Button Mushrooms during Storage
, Ebtihal Khojah 1, Abeer Elhakem 2, Nada Benajiba 3, Murthy Chavali 4, Kambhampati Vivek 5, Abdullah Iqbal 6 and Mahmoud Helal 7Round 1
Reviewer 1 Report
The manuscript reports an investigation of three kinds of coatings based on chitosan applied on button mushrooms. Some quality parameters were monitored up to 12 days of storage, to determine the effect of the different coatings on mushrooms attributes.
The study is interesting, nevertheless some points still need to be clarified. In particular, the safety of the treatments was not discussed. The authors report that nano-films of silica and titanium in low concentrations are considered as safe by FDA, nevertheless they don’t report if the quantities used are sufficiently low to be safe for consumers.
Moreover, also data on the impact of the coatings on the flavour and taste of the mushrooms are missing. Are the coatings going to be removed during the product washing before consumption?
The authors declared to have performed the analysis of significance by ANOVA, however in figure 1 and 3 they did not report the results neither discuss the results in terms of significance. In my opinion they should include these data to clarify the importance of the different treatments. Also the discussion about significant reults should be improved and corrected at least for microbiological data.
The English language along the text should be checked and revised particularly in some critical points which make the sentences difficult to be understood.
Some specific points are reported below.
L 47: falvor?
L52: maybe “such as those with...” could be more understandable.
L 56: please check the use of italic.
L59: why the microbial groups are included in brackets?
L79-80: again, why some chitosan solutions are reported in brackets?
L86-87: the verb is missing.
Equation 3: a bracket is missing
L113: please check the measure units of the speed.
L129: aliquant?
L148-154: please check the sentences because they sound as something is missing.
L80: Where did the nano-silica and nano-titanium come from? Were they buyed? Were they previously prepared? The authors should add these details and also add some information on their characterization.
L 82: Are the authors sure that deionized water can be considered as a correct control sample? Could the mushroom be somehow damaged by the deionized water, being it an hypotonic solution?
L149-150: Is there any index to determine when a mushroom results unacceptable for the market?
Moreover, all the coatings preserved the mushrooms for high water loss, however why the nano-silica and nano-titanium were more active than chitosan alone? Do the authors have any explanation?
L159-166: why nano-silica always determined a pH significantly higher than control and other samples?
Table 1: While chitosan and chitosan/nano-titanium at T0 ahowed L* results very similar to those obtained for the control, on the contrary chitosan/nano-silica showed a much lower value. Which could be the reason? When observed by naked eye, were these samples different?As the authors declared, the color and the appearance of the mushrooms are a very important choice criterium for the consumers point of view in order to decide wheter to buy the product or not, so beside the objective measure of the color, also these data could be useful.
L191: please change the verb as the sentence appears to be not correct.
Figure 2: in the authors opinion, which is the reason why so different results in BI were obtained at 12 days of storage for all the samples?
L208: repining?
L234-237: please improve the sentence and make it clearer.
About PPO, undoubtely chitosan/nano-titanium gave the best results, followed by chitosan/nano-silica. In the authors opinion, how can these nanoparticles improve this effect with respect to simple chitosan coating? Which is the explanation?
L269: remove the full stop after the reference 12.
As regards Microbial load, the authors discussed the results as significantly high or coating treatments as significantly effective on the microbial load, nevertheless in the graph 5, they report similar results for all the samples in each analysis time. For this reason, it is not correct to discuss the data in this way, in particular if they report the microbial load of 6.12, 6.16 and 6.17 CFU/g, as different results. The results are different only in the second decimal number, and from a microbiological point of view, the microbial loads of the different samples are exactly the same. Please correct and discuss properly. Do the different coatings exert an antimicrobial effect?
Conclusion: the conclusions are quite vague. Are the data sufficient to select one coating treatment as the best one?
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
In this work by Rokayya and co-workers, the authors investigated how the coating of white button mushrooms with nano-films affects physical, mechanical, chemical, and microbial properties. The study is valuable and potentially interesting to the readership of Coatings. However, several issues must be taken care of before this paper can be accepted for publication. Please find the suggestions below:
1) The introduction section is very brief as it is half a page long and contains only 11 references. Please extend it to include the appropriate papers, which are relevant to this work.
2) The "in this work" section should also be extended. The readers need to know the summarized contents of the article to judge if this paper is relevant and interesting to read.
3) There are not enough experimental details to reproduce the study. Without providing the experimental conditions, other researchers cannot build on this work, which very much limits its impact and negates its purpose. For instance, chitosan parameters are not given. Moreover, the source of nano-silica and nano-titanium is not specified. Next, spray deposition parameters are not exhaustive. The amount of deposited solution, nozzle, air pressure, distance of the gun from mushrooms, etc., should be added. Please include such information in the revised version of the manuscript.
4) Plots formatting makes it very hard to understand them, and the quality is low. For example, the used symbols are too small. Consider enlarging the symbols and coloring the lines to guide the eye. Fig. 2 lacks a dedicated explanation of what are the a, b, and c letters in the caption.
5) There are some considerable non-monotonic changes in Fig. 1 b and c (the letters are actually missing from the figure), but they are neglected from the discussion. The pH and TSS increase and decrease in a seemingly random fashion. Please interpret this finding.
6) Conclusions section is very brief. It should be extended to include an appropriate summary of what was done, the impact, and the future outlook.
7) Most importantly, the authors specified: "Nano-films such as silica and titanium dioxides are considered to be safe with low concentration according to the US Food and Drug Administration [11]." (Lines 63-65). Therefore, it is of utmost importance to:
- report what the safe concentration of these compounds is
- measure the concentration of these compounds in this study
- specify if the employed concentration was within the safety limits; otherwise, even if the mushroom can be preserved for a longer time, they may be inedible
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
The manuscript entitled “Investigating the nano-films effect on physical, mechanical properties, chemical changes, and microbial load contamination of white button mushrooms during storage”, presents the effect of chitosan, chitosan/nano-silica and chitosan/nano-titanium on quality of mushrooms samples during 12 days of storage at 4ºC. The results reveal the efficacy of application of these nano-film in prevention of degradation products during postharvest period and seems to be a promise postharvest treatment to achieve an extension of shelf-life of mushrooms. Below, the authors can see my suggestions, comments, and observation to improve and enhance the quality of manuscript.
In all manuscript, when the data is presented, appears between parentheses. In my opinion, the same data should be written without the parenthesis for reading clear of the evidence of lowest or highest effect.
2.1. Materials and sample treatments
Page 2, Line 87 – Add “was realized” at the end of sentence: “at an interval of 3 days up to 12 days of storage period, was realized.”
2.2.1. Weight loss, acidity, and total soluble solids concentrations
Page 2, Line 91 – Change “percentile” to “percentage”.
2.2.2. Colour investigation measurements
Page 3, Line 105-106 – The equation 2 need correction, the number 2 need to appear in superscript. Also, the authors need to introduce the definition of L0, a0 and b0 for a clear understanding of formula.
2.2.5. Headspace gas composition and PPO activity analysis
Page 4, Line 129 – “Aliquant”?
Page 4, Line 132 – More information regarding the brand, city and country of centrifuge need to add after “centrifuge….”
2.2.6. Microbial load contamination
Page 4, Line 137-138 – The mass of each sample is 15 grams? Or 25 grams? Normally, the ratio is 1 for 9 in determination of microbiological load.
- Results and discussion
Page 4, Line 146 - Correct the word “3. Results and dissections” to 3. Results and discussion”.
3.1. Weight loss (WL), pH, TSS changes
Page 4, Line 149-150 – The authors need to write the data when an increase during the storage period, was evidenced as observed “There was an extraordinary increase during the storage period, especially for the control samples after 12 days”.
Page 4, Line 150-151 – The mushroom is unacceptable for marketing when the weight loss percentage attain which value? Do you have a reference to prove this? Please add in the end of sentence.
Page 4, Line 154 – As previously referred, I suggest the elimination of parentheses when the data was presented.
Page 4, Line 154 – The study developed by Hosseini and Moradinezhad evaluated the same nano-film? Same mushrooms sample? Same storage period? More information regarding this is necessary to evidence the similarity between the presented study and the reported.
Page 4, Line 155-156 – Same evidence in this sentence, more information is necessary for discussion of results.
In all legend, at the end change the sentence “ Data are mean +/- SD, n=3” for “Data are presented as mean…”
Page 5, Line 161-162 – The sentence “The results showed that the values of pH were significantly different with all storage days, except the 9th day.” Need to be re-write since the pH of chitosan/nano-silica sample in 9th storage is significant different compared to others. And this difference is highest.
Page 5, Line 170-171 – The sentence “Various results were observed for TSS among the various coating treatments during storage are shown in Figure 1c.” need to be re-write for clear understanding, for example “The results of TSS in coated- treated mushroom during storage are shown in Figure 1c.”
Page 5, Line 173-174 – Why the TSS data presented in chitosan/nano-silica mushrooms is defined as best? Please clarify.
3.2. Colour parameters changes
Page 5, Line 176-177 – Please re-write the sentence “Mushrooms have a short shelf-life due to losing quality in addition to turning brown within short time as the main considerable parameter for consumer agreement is the colour [6]” for as example “Mushrooms have a short shelf-life due to quality loss expressed by colour changing from white to brown browning within short time as the main considerable parameter for consumer agreement is the colour [6]”
Page 5, Line 178 – Change “…for 12 days have been shown…” for “ …for 12 days are shown…”
Page 5, Line 179-180 – The L* value decrease in mushrooms samples coated with chitosan and chitosan/nano-titanium, but how much from the initial value? Please indicate this difference.
References:
Please verified the correct presentation of reference according the rules of Coatings.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The authors have improved the manuscript, replying to all the reviewers' comments, anche also changed the figures to render them more clear.
I only have a comment regarding the microbiological data, and in particular those reported in the conclusion. In fact, the ANOVA analysis clearly shows differences among the different days of storage, while the differences among th treatments applied and the control are little and often not significance. In fact the microbial load also grows during the storage and the numbers are similar to those shown by the control. For this reason is not appropriate to conclude that " the nano-films inhibit the microbial load contamination such as yeasts and mould during storage" as the authors did in the conclusion section, as the microbial loads in times 9 and 12 were not significantly different from the control.
Please reformulate. While chitosan alone or plus nano-materials are effective on the great part of the quality indexes considered, the same cannot be affirmed for the microbial growth.
Author Response
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Author Response File: Author Response.pdf
Reviewer 2 Report
I appreciate that the manuscript has been considerably improved based on the comments of all the referees. I recommend publication of the article.
Author Response
Comments and Suggestions for Authors 2
I appreciate that the manuscript has been considerably improved based on the comments of all the referees. I recommend publication of the article.
Author Response
Thanks a lot professor
Author Response File: 
Author Response.docx
