Preparation and Characterization of Ultrasound Treated Polyvinyl Alcohol/Chitosan/DMC Antimicrobial Films
Round 1
Reviewer 1 Report
The article is an interesting study that fits in with the trend of searching for new solutions that can improve existing solutions. I wonder if the authors have already considered which products they can use antimicrobial films for. Will it be the subject of further research, already in the matrix of specific foods?
Notes to the text of the article:
General:
Authors must pay special attention to the preparation of the text, because minor weaknesses affect its assessment. In many places there are no spaces between words (line 436 - is "leadto", and it should be rather "lead to"; line 176 - is "499mL"). Please also check the record of units used in the text to see if they are recorded as required by the magazine. In some places the unit is missing (Table 3, in case density).
In the same way, a uniform notation should be used for bacteria: "Gram-positive" (as on line 37) rather than "gram-positive" (line 173). The bacterial species are usually spelled with a lowercase letter - and in line 68 and 81 you can see "E. Coli. "
I also suggest swapping a few words that should not appear in a scientific article (line 35 "wonderful"; line 356 "phenomenon").
Specific remarks:
Introduction:
Line 31 - the abbreviations "PVA" and "CS" appear here. Their explanation appears only on lines 34 (CS) and 41 (PVA). The reader should be able to read the abbreviation marking in the place of its first use.
Line 54 - the word "hydrophilicity" is underlined and written in blue.
Materials and methods
Line 77 - the country of origin of the company is missing with the characteristics of chitosan.
Line 80 - the wording "highly concentrated" is vague. Please provide the exact acid concentration.
Line 85 - The methodology is described here by the authors or the number 25 entry cited in line 90? If the authors refer to literature, it should be mentioned much earlier in the text.
Line 89 - what equipment was used to "energetically stired" the mixture?
Line 91 - I suggest using a specific temperature value instead of "room temperature".
Line 115 - who is the author of the methodology for determining the "water vapor permeability" parameter? There is no reference to any literature.
Line 132 - who is the author of the methodology for determining "color properties"? Note as above.
Line 145 - the following would be clearer: "area (s)", thickness (d) and mass (m).
Line 150 - is it possible to provide more precise parameters of this marking: temperature and humidity?
Line 153 - the sentence is not entirely clear: it should be added what it was "2% concentration".
Line 160 - the phrase "wi" is in the pattern and "wi" is in the text.
Line 172 - Were they bacterial strains from some collection (e.g. ATCC)? Please provide their origin.
Results and discussion
Line 228 - I suggest authors check the citation of items 37 and 38, because there are a minimum of two authors or more in these items - not just one, as suggested in the tekst.
Line 230 - not "treament" but "treatment"; hard to read phrase "... had level effect level ..."
Lines 217 and 231 - was figure 1 cited correctly?
The text lacked reference to figures 3 and 4!
Line 255 - the abbreviation "WVTRs" is not explained here, it is only in Figure 5 that its expansion can be found.
Line 266 and 286 - the letter "a", which refers to statistics, is hard to read. Use a different entry, perhaps with a dash. The same applies to the signatures of other drawings and tables (table 3, figure 7 and figure 8).
Line 309 - unless the authors should refer to table 2, not to 1.
Lines 312 and 314 - standardize the record: "a-value" or "a * value" etc.
Line 322 - the value of the parameter is placed here (and in several other places) in parentheses, while the unit designation is out of parenthesis. Is this a valid entry?
Line 323 - the entry "1 wt% to 4 wt%" appears, which has not been used before.
Line 359 - please correct the beginning of the sentence on this line ("However, Excessive ...").
Lines 378-379 - please rewrite the sentence.
Line 395 - please add the reference number: rather "Alexy et al. [47] ".
"Antibacterial properties ..." - what was the method of determining microbial reduction? Because the methodology was not very readable. Is it based on the number of colonies on the plates, MIC or MBC? More details please.
Author Response
Comments and Suggestions for Authors 1：
The article is an interesting study that fits in with the trend of searching for new solutions that can improve existing solutions. I wonder if the authors have already considered which products they can use antimicrobial films for. Will it be the subject of further research, already in the matrix of specific foods?
We intend to use it for preserve strawberries, and thompson seedless grapes, etc. (Liu, Y.W.; Wang, S.Y.; Lan, W.J.; Qin W. Fabrication of polylactic acid/carbon nanotubes/chitosan composite fibers by electrospinning for strawberry preservation. Int. J. Biol. Macromol. 2109, 121, 1329-1336.) ( Lo’ay, A.A.; Taha, N.A.; EL-Khateeb, Y.A. Storability of ‘Thompson Seedless’ grapes: Using biopolymer coating chitosan and polyvinyl alcohol blending with salicylic acid and antioxidant enzymes activities during cold storage. Sci. Hortic. 2019, 234, 314-321.) Chitosan (CS) is a suitable material for designing food packaging, because it shows excellent film-forming capacity and barrier properties. In addition, CS has high antimicrobial activity against many pathogenic and spoilage microorganisms, including both Gram-positive and Gram-negative bacteria( Hosseinnejad, M.; MahdiJafari, S.; Evaluation of different factors affecting antimicrobial properties of chitosan. Int. J. Biol. Macromol. 2016, 85, 467-475.) Chitosan and polyvinyl alcohol have good food preservation effect, Bonilla et al. reported blend CS with PVA films at different compositions. Although CS incorporation in PVA films could provide the antimicrobial properties, CS addition strongly reduced the film’s stretching ability. ( Bonilla, J.; Fortunati, E.; Atarés, L.; Chiralt, A.; Kenny, J.M. Physical, structural and antimicrobial properties of poly vinyl alcohol–chitosan biodegradable films. Food Hydrocolloids. 2014, 35, 463-470.) The results showed that the addition of DMC increased the tensile properties of the composite films and can further improve the antibacterial effect of the film. Although the mechanism leading to the improvement in ultrasonic processing-induced bacteriostatic activity of PVA/CS/DMC composite films needs further study, the good physical properties and biodegradability attributes of this type of composite film prove its suitability as a degradable and antibacterial active packaging material.
The experiment has not yet started, but we intend to do more in-depth research on strawberry preservation. The barrier and antimicrobial properties of the composite film are suitable for strawberry preservation. In previous studies, the high WVP of film led to a slight decline in relative humidity within the packaging, which would be beneficial for postharvest vegetable and fruit quality. Furthermore, there was no condensate water when using materials with high WVP. (Niu, B.; Shao, P.; Chen, H.J.; Sun, P.L. Structural and physiochemical characterization of novel hydrophobic packaging films based on pullulan derivatives for fruits preservation. Carbohydr. Polym. 2019, 208, 276-284.) (Liu, Y.W.; Wang, S.Y.; Lan, W.J.; Qin W. Fabrication of polylactic acid/carbon nanotubes/chitosan composite fibers by electrospinning for strawberry preservation. Int. J. Biol. Macromol. 2019, 121, 1329-1336.). Thanks.
Notes to the text of the article: General: Authors must pay special attention to the preparation of the text, because minor weaknesses affect its assessment. In many places there are no spaces between words (line 436 - is "leadto", and it should be rather "lead to"; line 176 - is "499mL"). Please also check the record of units used in the text to see if they are recorded as required by the magazine. In some places the unit is missing (Table 3, in case density).
Revised. Thanks.
In the same way, a uniform notation should be used for bacteria: "Gram-positive" (as on line 37) rather than "gram-positive" (line 173). The bacterial species are usually spelled with a lowercase letter - and in line 68 and 81 you can see "E. Coli. "
Corrected. Thanks.
I also suggest swapping a few words that should not appear in a scientific article (line 35 "wonderful"; line 356 "phenomenon").
Done. Thanks.
Specific remarks:
Introduction: Line 31 - the abbreviations "PVA" and "CS" appear here. Their explanation appears only on lines 34 (CS) and 41 (PVA). The reader should be able to read the abbreviation marking in the place of its first use.
Corrected. Thanks.
Line 54 - the word "hydrophilicity" is underlined and written in blue.
Corrected. Thanks.
Materials and methods
Line 77 - the country of origin of the company is missing with the characteristics of chitosan.
Yes, we added. The chitosan was the same as our pervious paper (Liu, Y.W.; Wang, S.Y.; Lan, W.T. Fabrication of antibacterial chitosan-PVA blended film using electrospray technique for food packaging applications. Int. J. Biol. Macromol. 2018, 107, 848-854.). Thanks.
Line 80 - the wording "highly concentrated" is vague. Please provide the exact acid concentration.
Added. Thanks.
Line 85 - The methodology is described here by the authors or the number 25 entry cited in line 90? If the authors refer to literature, it should be mentioned much earlier in the text.
The author refers to the concentration of DMC in 25 entries, so 25 entries are quoted here. Thanks.
Line 89 - what equipment was used to "energetically stired" the mixture?
Corrected. Thanks.
Line 91 - I suggest using a specific temperature value instead of "room temperature".
Replaced. Thanks.
Line 115 - who is the author of the methodology for determining the "water vapor permeability" parameter? There is no reference to any literature.
This value was measured using as Zhang et al. reported ( Zhang, D.; Zhou, W.; Wei, B.; Wang, X.; Tang, R.P.; Nie, J.M.; Wang J. Carboxyl-modified poly(vinyl alcohol)-crosslinked chitosan hydrogel films for potential wound dressing. Carbohydr. Polym. 2015, 125, 189-199.). Thanks.
Line 132 - who is the author of the methodology for determining "color properties"? Note as above.
The method was described by Vaezi et al. (Vaezi, K.; Asadpour, G.; Sharifi H. Effect of ZnO nanoparticles on the mechanical, barrier and optical properties of thermoplastic cationic starch/montmorillonite biodegradable films. Int. J. Biol. Macromol. 2019, 124, 519-529.). Thanks.
Line 145 - the following would be clearer: "area (s)", thickness (d) and mass (m).
Corrected. Thanks.
Line 150 - is it possible to provide more precise parameters of this marking: temperature and humidity?
The samples were treated at room temperature (23 0C) and humidity (50%) before testing. (Standard I S O. 1183, “Plastics—Methods for determining the density of non-cellular plastics—Part 1: Immersion method, liquid pyknometer method and titration method,”[J]. International Organization for Standardization, 2012.). Thanks.
Line 153 - the sentence is not entirely clear: it should be added what it was "2% concentration".
This article was written. Thanks.
Line 160 - the phrase "wi" is in the pattern and "wi" is in the text.
Corrected. Thanks.
Line 172 - Were they bacterial strains from some collection (e.g. ATCC)? Please provide their origin.
For antimicrobial tests, culture media for Gram-negative bacteria (Escherichia coli ATCC 25922, Salmonella enterica ATCC 14028 and Pseudomonas aeruginosa ATCC 27853), and Gram-positive bacteria (Bacillus cereus ATCC 11778 and Staphylococcus aureus ATCC 25923) were purchased from the institute of standards and industrial research of Iran. Bacterial strains were grown in MuellerHinton Broth (MHB) medium (Merck, Germany) at 37 °C for 24 h before each test. (Heydari-Majd, M.; Ghanbarzadeh, B.; Shahidi-Noghabi, M.; Shahidi-Noghabi M. A new active nanocomposite film based on PLA/ZnO nanoparticle/essential oils for the preservation of refrigerated Otolithes ruber fillet. Food Packaging Shelf. 2019, 19, 94-103.). Thanks.
Results and discussion: Line 228 - I suggest authors check the citation of items 37 and 38, because there are a minimum of two authors or more in these items - not just one, as suggested in the tekst.
Corrected. Thanks.
Line 230 - not "treament" but "treatment"; hard to read phrase "... had level effect level ..."
Sorry, corrected. Ultrasonic processing had a certain degree of impact on the hydrogen bonds formed between the PVA and DMC molecules. Thanks.
Lines 217 and 231 - was figure 1 cited correctly?
Corrected. Thanks.
The text lacked reference to figures 3 and 4!
Corrected. Thanks.
Line 255 - the abbreviation "WVTRs" is not explained here, it is only in Figure 5 that its expansion can be found
Sorry, it should be WVTR instead of WVTRs. Thanks.
Line 266 and 286 - the letter "a", which refers to statistics, is hard to read. Use a different entry, perhaps with a dash. The same applies to the signatures of other drawings and tables (table 3, figure 7 and figure 8).
The author has used the dash in the pictures and revised the signatures of the table. Thanks.
Line 309 - unless the authors should refer to table 2, not to 1.
Replaced. Thanks.
Lines 312 and 314 - standardize the record: "a-value" or "a * value" etc.
Corrected. Thanks.
Line 322 - the value of the parameter is placed here (and in several other places) in parentheses, while the unit designation is out of parenthesis. Is this a valid entry?
Corrected. Thanks.
Line 323 - the entry "1 wt% to 4 wt%" appears, which has not been used before.
Revised. Thanks.
Line 359 - please correct the beginning of the sentence on this line ("However, Excessive ...").
Done. Thanks.
Lines 378-379 - please rewrite the sentence.
Re-wroted. Thanks.
Line 395 - please add the reference number: rather "Alexy et al. [47] ".
Added. Thanks.
"Antibacterial properties ..." - what was the method of determining microbial reduction? Because the methodology was not very readable. Is it based on the number of colonies on the plates, MIC or MBC? More details please.
Added. The spread plate method is a counting method based on a single colony formed by microorganisms on a solid medium, that is, a single cell multiplication, that is, one colony represents a single cell. When counting, first make the sample to be tested into a uniform series of dilutions, try to spread the microbial cells in the sample, so that a single cell exists (otherwise a colony does not only represent a cell), and then take a certain dilution, certain The amount of the dilution was inoculated into the plate so that it was evenly distributed in the medium in the plate. After culture, colonies are formed by single cell growth and reproduction, and the number of colonies is counted, and the number of bacteria in the sample can be calculated. The number of bacteria counted by this method is the number of colonies that grow on the medium, so it is also called the viable count. And it is based on the number of colonies on the plates. Thanks.
Reviewer 2 Report
The manuscript deals with the preparation and characterization of ultrasound treated polyvinyl alcohol/chitosan/DMC antimicrobial films.
The English language is poor and must be revised.
Please separate values from units, e.g. “7.6 kDa” not “7.6kDa”.
Introduction
Line 68- “(Escherichia Coli)”??Please format scientific names in accordance.
Materials and methods
Line 88- “The different qualities DMC(2, 4, 6, 8 g)”???
Line 90- “Glycerol (2 mL/200 mL)”??2 mL per 200 mL of film forming solution??
Line 93- “in the ultrasonic limpid processor for 0, 30, and 60 min respectively”??probe??bath??brand??temperature control??effect of 60 min??only due to cavitation??
Table 1- different % of DMC are according to which concentrations??1%, 2%... of?
Line 131- “Color properties”, illuminant used??ºobserver??
Line 153- “A typical PVA/CS/DMC biodegradable films with a concentration of 2% were buried…”??why only this film was tested??
Line 170- “Antimicrobial experiment”???, why not a diffusion test???
Results and discussion
Line 230- “Ultrasonic treament had a definite level effect level on the hydrogen bonds…”???
Table 2- “A Values with different superscripts for each parameter…”???
Line 322- “As the DMC concentration grew from 1 wt% to 4 wt%, the tensile strength of the fiber by degrees declined, while the elongation at break grew first then declined [26].”??results from this study??
Line 353- “Present findings showed that when the ultrasonic time was 30 min, the density of the PVA/CS/DMC composite film increased significantly (p < 0.05)…”??for all samples??Please check your results.
Line 358- “…and more uniform network structure.However, Excessive duration of ultrasonic time may…”???
Line 384- “As shown in Figure 8, the degradation percentage of DMC composite membrane with 2% concentration increased with the extension of ultrasonic treatment time”??why??This part needs to be clarified.
Line 403- “Table 4 shows the antibacterial efficiency of the PVA/CS/DMC films with different DMC concentrations.”?? PVA/CS control film??
Line 419- “Ultrasonic processing could improve the bacteriostatic effects of materials to some extent. In comparison with ultrasonic 30 min, the consequences of this study showed the growth inhibition of S. aureus and E. coli slightly raised to (81.15±0.38%) and (74.42±1.06%) after ultrasonic 60min, respectively.”??why??better release of compounds?? This part needs also to be clarified.
Conclusion
Please do not repeat your results and present your main conclusions.
References
Line 458- “pva/chitosan”??PVA?
Line 483- Please format the title of each article according to the guide for authors.
Line 495- “Synthesis, characterization and comparison of pam, cationic pdmc and p(am‐co‐dmc) based on solution polymerization”??Please correct title.
Author Response
Comments and Suggestions for Authors 2：
The manuscript deals with the preparation and characterization of ultrasound treated polyvinyl alcohol/chitosan/DMC antimicrobial films.
The English language is poor and must be revised.
Revised. Thanks.
Please separate values from units, e.g. “7.6 kDa” not “7.6kDa”.
Done. Thanks.
Introduction: Line 68- “(Escherichia Coli)”??Please format scientific names in accordance.
Corrected. Thanks.
Materials and methods: Line 88- “The different qualities DMC(2, 4, 6, 8 g)”???
The different qualities DMC (2, 4, 6, 8 g) solution were dropped into PVA/CS solution (200g) and configured into PVA/CS/DMC solutions with different concentrations of 1%, 2%, 3% and 4% ( Chen, J.H.; Liu, Q.L.; Fang, J.; Zhu, A.M.; Zhang, Q.G. Composite hybrid membrane of chitosan–silica in pervaporation separation of MEOH/DMC mixtures. J. Colloid Interface Sci. 2007, 316, 580-588.) Thanks.
Line 90- “Glycerol (2 mL/200 mL)”??2 mL per 200 mL of film forming solution??
Yes, the addition of Glycerol is 2 mL per 200 mL of film forming solution. Thanks.
Line 93- “in the ultrasonic limpid processor for 0, 30, and 60 min respectively”??probe??bath??brand??temperature control??effect of 60 min??only due to cavitation??
Each solution was dealt with ultrasound in the ultrasonic limpid processor for 0, 30, and 60 min respectively. It is Bath. Brand (ultrasonic bath (Kunshan Ultrasonic Instrument Co., Ltd., Model: KQ100DE, 50 W); The temperature is fixed. The temperature we set is 40 degrees centigrade. (Abral, H.; Basri, A.; Muhammad, F.; Fernando, Y.; Hafizulhaq, F.; Mahardik, M.; Sugiarti, E.; Sapuan, S.M.; Ilyas, R.A.; Stephane, I. A simple method for improving the properties of the sago starch films prepared by using ultrasonication treatment. Food Hydrocolloids. 2019, 93, 276-283.); This is mainly attributed to the cavitation effect of ultrasonication. (Liu, Y.W.; Wang, S.Y.; Lan, W.J.; Qin W. Development of ultrasound treated polyvinyl alcohol/tea polyphenol composite films and their physicochemical properties. Ultrason. Sonochem. 2019, 51, 386-394.) (Li, W.; J. Yue, J.Q.; Liu, S.X. Preparation of nanocrystalline cellulose via ultrasound and its reinforcement capability for poly(vinyl alcohol) composites, Ultrason. Sonochem. 2012, 19, 479–485.). Thanks.
Table 1- different % of DMC are according to which concentrations??1%, 2%... of?
According to PVA/CS solution (Solutions of 10% (w/v) PVA and 3% (w/v) CS were resolved in same acetic acid solution volume separately. To form homogenous PVA/CS solution with the volumetric proportion of 1:1). 1% means dissolving 2g of DMC in PVA/CS solution (200 g); 2% means dissolving 4g of DMC in PVA/CS solution (200 g)；3% means dissolving 6g of DMC in PVA/CS solution (200 g)；4% means dissolving 8g of DMC in PVA/CS solution (200 g). Thanks.
Line 131- “Color properties”, illuminant used??ºobserver??
The color values of L*, a* and b* were determined by the colorimeter. (The color parameter values of the standard plate are L* = 89.05 , a* = 1.97, b* = −5.96.) The total color difference (ΔE*) was calculated as follows:
Where ΔL = L*standard − L*sample, Δa = a*standard − a*sample, Δb = b*standard − b*sample. (Vaezi, K.; Asadpour, G.; Sharifi H. Effect of ZnO nanoparticles on the mechanical, barrier and optical properties of thermoplastic cationic starch/montmorillonite biodegradable films. Int. J. Biol. Macromol. 2019, 124, 519-529.) Thanks.
Line 153- “A typical PVA/CS/DMC biodegradable films with a concentration of 2% were buried…”??why only this film was tested??
It was original intended to measure only the film of PVA/CS/DMC-2, because the film with a 2% concentration of DMC is the most typical of the five kinds of films. In subsequent experiments, for more complete results, the degradation properties of PVA/CS, PVA/CS/DMC-1, PVA/CS/DMC-2, PVA/CS/DMC-3, PVA/CS/DMC-4films have been tested. Corrected. Thanks.
Line 170- “Antimicrobial experiment”???, why not a diffusion test???
We have consulted many PVA and CS literatures. The antimicrobial method (Spread plate method) was selected based on the following references. (Zhang, R.; Wang, Y.H.; Ma D.H; SaeedAhmed, S. Qin, W. Liu, Y.W. Effects of ultrasonication duration and graphene oxide and nano-zinc oxide contents on the properties of polyvinyl alcohol nanocomposites. Ultrason. Sonochem. 2019, 59, 104731.) (Liu, B.; Xu, H.; Zhao, H. Y.; Liu, W.; Zhao, L.Y.; Li, Y. Preparation and characterization of intelligent starch/PVA films for simultaneous colorimetric indication and antimicrobial activity for food packaging applications. Carbohydr. Polym. 2017, 157, 842-849.) (Indumathi, M.P.; Saral Sarojini K.; Rajarajeswari, G.R. Antimicrobial and biodegradable chitosan/cellulose acetate phthalate/ ZnO nano composite films with optimal oxygen permeability and hydrophobicity for extending the shelf life of black grape fruits. Int. J. Biol. Macromol. 2019, 132, 1112-1120.). Thanks.
Results and discussion: Line 230- “Ultrasonic treament had a definite level effect level on the hydrogen bonds…”???
Corrected. Thanks.
Table 2- “A Values with different superscripts for each parameter…”???
This experiment has two factors. So “A” and “a” were used to show the different factors. Thanks.
Line 322- “As the DMC concentration grew from 1 wt% to 4 wt%, the tensile strength of the fiber by degrees declined, while the elongation at break grew first then declined [26].”??results from this study??
Sorry, the description of tensile strength and elongation at break is not clear. We revised as follows: Under the same ultrasonic time, when the DMC concentration grew from 1% to 4%, the general trend of the tensile strength of the fiber by grew first then declined, while the elongation at break first grew, and then declined.
The results of this paper was revised as follows: 1. Under the same ultrasonic time, when the DMC concentration grew from 1% to 4%, the general trend of the tensile strength of the fiber by grew first then declined, while the elongation at break grew first then declined. 2. When the composite film with concentrations of DMC of 2%, the elongation at break is the highest at (273.70% ± 4.86) % (without sonication), 13.83% better than PVA/CS film (240.44% ± 6.19) %. 3. With the increase in time the tensile strength values for all sonicated composite film(0%~2%DMC) were higher than that for the non-sonicated ones owning to the enhanced interfacial hydrogen that bonded between it and matrix. 4. As increasing the time of ultrasound, the tensile strength of the sonicated composite films(3%~4%DMC) was lower than that for the non-sonicated ones. 5\When the ultrasonic time is 30 min, the elongation at break of the films increases significantly (p < 0.05), but its tensile strength generally shows a decreasing trend. Thanks.
Line 353- “Present findings showed that when the ultrasonic time was 30 min, the density of the PVA/CS/DMC composite film increased significantly (p < 0.05)…”??for all samples??Please check your results.
Corrected as follows: Present findings showed that when the ultrasonic time was 30 min, the density of the PVA/CS, PVA/CS/DMC-1, PVA/CS/DMC-2 and PVA/CS/DMC-3 composite films increased significantly when the ultrasonic time was 30 min. (P < 0.05). Thanks.
Line 358- “…and more uniform network structure. However, Excessive duration of ultrasonic time may…”???
When the ultrasound time was short (30 min), appropriate ultrasonic time can make ultrasound through a liquid creates pressure to form a denser and more uniform network structure. However, excessive duration of ultrasonic time (60 min) may cause excessive damage to the polymer, resulting in excessive pores on the polymer surface to reduce its density. (Wang, D.L.; Lv, R.L.; Ma, X.B.; Zou, M.M.; Wang, W.J.; Yan, L.; Ding, T.; Ye, X.Q.; Liu, D.H. Lysozyme immobilization on the calcium alginate film under sonication: Development of an antimicrobial film. Food Hydrocolloids. 2018, 83, 1-8.). Thanks.
Line 384- “As shown in Figure 8, the degradation percentage of DMC composite membrane with 2% concentration increased with the extension of ultrasonic treatment time”??why??This part needs to be clarified.
We corrected the wrong description. Thanks.
Line 403- “Table 4 shows the antibacterial efficiency of the PVA/CS/DMC films with different DMC concentrations.”?? PVA/CS control film??
Since many studies have been done on PVA/CS films (Bourakadi, K.E.; Merghoub, N.; Fardioui, M.; Mekhzoum, M.E.M.; Kadmiri, I.M.; Essassi, E.M.; Qaiss, A.K.; Bouhfid, R. Chitosan/polyvinyl alcohol/thiabendazoluim-montmorillonite bio-nanocomposite films: Mechanical, morphological and antimicrobial properties. Composites Part B 2019, 172, 103-110.) (Liu, Y.W.; Wang, S.Y.; Lan, W.T. Fabrication of antibacterial chitosan-PVA blended film using electrospray technique for food packaging applications. Int. J. Biol. Macromol. 2018, 107, 848-854.) (Wang, H.L.; Zhang, R.; Zhang, H.; Jiang, S.W.; Liu, H.; Sun, M.; Jiang, S.T. Kinetics and functional effectiveness of nisin loaded antimicrobial packaging film based on chitosan/poly(vinyl alcohol). Carbohydr. Polym. 2015, 127, 64-71.) Show more the purpose of this experiment is to obtain more optimized antimicrobial films by adding different concentrations of DMC and ultrasonic processing at different times, which will provide a basis for further research on the preservation of food. Thanks.
Line 419- “Ultrasonic processing could improve the bacteriostatic effects of materials to some extent. In comparison with ultrasonic 30 min, the consequences of this study showed the growth inhibition of S. aureus and E. coli slightly raised to (81.15±0.38%) and (74.42±1.06%) after ultrasonic 60min, respectively.”??why??better release of compounds?? This part needs also to be clarified.
Some researchers have reported that sonication can loosen the network structures of membranes and promote the release of active substance release. Another possible reason is the higher antimicrobial activity of the membrane prepared via ultrasonication. (Wang, D.; Lv, R.; Ma, X.; Zou, M.; Wang, W.; Yan, L.; Ding, T.; Ye, X.; Liu,D.; Lysozyme immobilization on the calcium alginate film under sonication: Development of an antimicrobial film, Food Hydrocolloid. 2018, 83, 1-8.). Thanks.
Conclusion: Please do not repeat your results and present your main conclusions.
In this research, PVA/CS/DMC that packaged substances with bacteriostatic activity were successfully prepared by using the polymer that blended approach. The affects of ultrasonic treatment period on the characteristics of the composite films were researched. The consequences showed that though ultrasonic treatment cut the elongation and tensile strength down at break for these ingredients in its early phases, it could enhance their barrier property and light transmittance performance. Overall, the results showed that the ultrasonic processing increased the tensile strength and elongation at break of the composite films. When the DMC concentration was 2% and the ultrasonic treatment duration was 30 min, the most excellent total properties were indicated by the films. The optimal PVA/CS/DMC-2 composite film showed notable activity against E. coli and S. aureus. Although the mechanism leading to the improvement in ultrasonic processing-induced bacteriostatic activity of PVA/CS/DMC composite films needs further study, this composite film type’s biodegradability characteristics and high physical characteristics proved its applicability as an antibacterial and biodegradable active material for packaging. Thanks.
References
Line 458- “pva/chitosan”??PVA?
Revised. Thanks.
Line 483- Please format the title of each article according to the guide for authors.
Done. Thanks.
Line 495- “Synthesis, characterization and comparison of pam, cationic pdmc and p(am‐co‐dmc) based on solution polymerization”??Please correct title.
Corrected. Thanks.
Round 2
Reviewer 2 Report
The English language must still be revised.
Materials and methods
Line 84- “0.5 h. DMC(2, 4, 6, 8 g) solutions with different qualities were dropped into”???or different quantities??
Line 141- “Color properties”, illuminant used??ºobserver??D65 and 10º???
Line 166- “The varying ultrasonication time of the sample were buried into the soil that was 10 cm away from the earth’s surface and marked. We removed the buried samples from the soil per 5 days, cleaned them with deionized water, dried them at 60°C until the weight of the films become stable.”???Please rephrase.
Line 175- “By measuring weight loss upon drying in an oven at 110°C, the water content of films was ascertained until constant weight was obtained(dry sample weight).”???Please rephrase.
Results and discussion
Line 365- “Present findings showed that when the ultrasonic time was 30 min, the density of the PVA/CS, PVA/CS/DMC‐1, PVA/CS/DMC‐2 and PVA/CS/DMC‐3 composite films increased significantly when the ultrasonic time was 30 min. (P < 0.05)”???Please rephrase.
Line 422- “In this study, the PVA/CS/DMC film was significantly more antimicrobial than PVA/CS film (p < 0.05).”?? PVA/CS control film tested??This part needs to be improved.
Conclusion
Please format scientific names in italic.
Author Response
Comments and Suggestions for Authors 2：
The English language must still be revised.
We fully revised. Thanks.
Materials and methods
Line 84- “0.5 h. DMC(2, 4, 6, 8 g) solutions with different qualities were dropped into”???or different quantities??
Corrected. Thanks.
Line 141- “Color properties”, illuminant used??ºobserver??D65 and 10º???
The illuminant is D65, and the observer is 10º. The parameter links of the instrument are attached below: http://www.shanion.net/seven-Products-1680294/. (Wang, L.Y.; Dong, Y.; Men, H.T.; Tong, J.; Zhou, J. Preparation and characterization of active films based on chitosan incorporated tea polyphenols. Food Hydrocolloids. 2013, 32, 35-41.). Thanks.
Line 166- “The varying ultrasonication time of the sample were buried into the soil that was 10 cm away from the earth’s surface and marked. We removed the buried samples from the soil per 5 days, cleaned them with deionized water, dried them at 60°C until the weight of the films become stable.”???Please rephrase.
We buried the sample into the soil 10 cm depth from the surface of earth. We removed buried samples from the soil each 5 days, cleaned them with deionized water, and dried them at 60 °C until the weight of the films without changed. Thanks.
Line 175- “By measuring weight loss upon drying in an oven at 110°C, the water content of films was ascertained until constant weight was obtained(dry sample weight).”???Please rephrase.
Yes, corrected. Through the measurement of weight loss by drying in an oven at 110°C until the sample reached constant weight (dry sample weight), we ascertained films’ water content. Thanks.
Results and discussion
Line 365- “Present findings showed that when the ultrasonic time was 30 min, the density of the PVA/CS, PVA/CS/DMC‐1, PVA/CS/DMC‐2 and PVA/CS/DMC‐3 composite films increased significantly when the ultrasonic time was 30 min. (P < 0.05)”???Please rephrase.
Present findings showed that the density of PVA/CS, PVA/CS/DMC-1, PVA/CS/DMC-2 and PVA/CS/DMC-3 composite films significantly increased when the ultrasonic time was 30 min (p < 0.05). Thanks.
Line 422- “In this study, the PVA/CS/DMC film was significantly more antimicrobial than PVA/CS film (p < 0.05).”?? PVA/CS control film tested??This part needs to be improved.
We correct the wrong description. We tested the PVA/CS control film and supplemented antimicrobial properties of PVA/CS films. Thanks.
Conclusion
Please format scientific names in italic.
Done. Thanks.
Round 3
Reviewer 2 Report
The manuscript was improved.
