Edible Micro-Sized Composite Coating Applications on Post-Harvest Quality of Sweet Cherry Fruits

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The research lacks careful analysis of significant differences in results, especially the representation in the charts is not standardized enough.

Author Response

Dear Reviewer,

Thank you for the suggestions you have made regarding our article. The changes made regarding your suggestions are stated in the article.

 

- The research lacks careful analysis of significant differences in results, especially the representation in the charts is not standardized enough.

All figures were redrawn considering the suggestion.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Lines 1-3: The title of the manuscript is too general and does not reflect the scope of the study. The title is more appropriate for a review manuscript.

Lines 24-24: The manuscript does not include the "selenium microparticles (SeMPs) green-synthesized from black tea leaf extracts" method referred to by the Authors. The word "synthesized" is repeated twice.

Lines 82-84: From two brief sentences it follows that selenium is an essential dietary component and used in food fortification and dietary supplementation. However, the authors should explain the purpose of adding selenium to the chitosan coating. This is a weak point of the manuscript.

Lines 87-88: The authors did not discuss the available information on the essential thyme oil they used in the coating and limited themselves to one general information on essential oils. This is another weakness of section 1. Introduction.

Lines 108-113: In section 2. Materials and Methods there is no information on the origin of thyme essential oil.

Lines 116-118: The transformation of selenium into micro-sized particles is not discussed, reference is made to the article [20] entitled „Green synthesis of iron nanoparticles by green tea and black tea leaves extract”. Selenium is not iron, so I conclude that the method of obtaining selenium micro-sized particles is missing and should be discussed. One sentence from lines 135-136 should be moved higher, i.e. to line 130.

Lines 126-130: The authors mentioned the names of four coating solutions, but did not discuss the method of preparing coating solutions, their chemical composition. How much selenium and how much thyme oil was in the chitosan solution?

Line 136: what does control mean? Are these uncoated sweet cherries?

Lines 185-187: Are these two sentences about the reviewer's comments on the manuscript? Why were they included in the manuscript?

Line 351: There is no Table 6 in the manuscript.

Figures 3,4,5, 6: The lines representing coated cherry fruits (orange lines) were covered with which of the four coatings: 1. CsMPs (Chitosan colloidal solution); 2. CsMPs+Oil (Chitosan colloidal solution + thyme essential oil); 3. CsMPs+SeMPs (Chitosan colloidal solution + Selenium colloidal solution); 4. CsMPs+SeMPs+Oil (Chitosan colloidal solution + Selenium colloidal solution + thyme essential oil) ? This is unclear.

Lines 360-375: The results shown in Figure 4, 5 and 6 are not different (lines overlap). Positive changes are only visible in Figure 3. The conclusion is too general and does not reflect all the results obtained in the study.

Author Response

Dear Reviewer,

Thank you for the suggestions you have made regarding our article. The changes made regarding your suggestions are stated in the article. Corrections in the article are marked in yellow

 

- Lines 1-3: The title of the manuscript is too general and does not reflect the scope of the study. The title is more appropriate for a review manuscript.

The title of the manuscript was revised as "Edible Micro-Sized Composite Coating Applications on the Post-Harvest Quality of Sweet Cherry Fruits"

 

- Lines 24-24: The manuscript does not include the "selenium microparticles (SeMPs) green-synthesized from black tea leaf extracts" method referred to by the Authors. The word "synthesized" is repeated twice.

This sentence was revised as ….: For this research, a nature-based solutions (NBSs) was applied, using micro-sized chitosan (CsMPs) and selenium microparticles (SeMPs), which are green-synthesized from black tea leaf extracts, and thyme essential oil.

 

- Lines 82-84: From two brief sentences it follows that selenium is an essential dietary component and used in food fortification and dietary supplementation. However, the authors should explain the purpose of adding selenium to the chitosan coating. This is a weak point of the manuscript.

Added additional information regarding Selenium: Within permissible bounds, the micro-sized selenium particles exhibit decreased cytotoxicity regarding higher organisms (humans, animals, fish, and crop plants), but these particles are also highly bioactive, suppressing bacteria, fungi, and eventually cancerous cells, which increases the usefulness of particles in the fields of biomedicine, pharmacy, and dietary intake [13]. The green produced micro-sized selenium particles —especially when combined with plant extracts—were added to prescription drugs that contained antioxidant and anticancer agents as well as ECs for meat products and agricultural crops [14].

 

- Lines 87-88: The authors did not discuss the available information on the essential thyme oil they used in the coating and limited themselves to one general information on essential oils. This is another weakness of section 1. Introduction.

Added additional information regarding essential oils: The acceptance of plant volatiles as safe (GRAS) makes it possible to use essential oils in edible coating technology to increase the safety and shelf life of fruits and vegetables. Essential oils, which have antimicrobial effects, are used extensively to prevent microbial spoilage. The antimicrobial effect of essential oils is due to the ability of many oils and aroma compounds they contain to reduce or stop the production of mycotoxins by molds [17].

 

- Lines 108-113: In section 2. Materials and Methods there is no information on the origin of thyme essential oil.

The origin of thyme oil was added as “Thyme essential oil (TEO) was supplied from the oil extraction unit, Erciyes University”.

 

- Lines 116-118: The transformation of selenium into micro-sized particles is not discussed, reference is made to the article [20] entitled „Green synthesis of iron nanoparticles by green tea and black tea leaves extract”. Selenium is not iron, so I conclude that the method of obtaining selenium micro-sized particles is missing and should be discussed. One sentence from lines 135-136 should be moved higher, i.e. to line 130.

The study on the synthesis of the iron element was used as a reference. The average size of the microparticles obtained after synthesis was measured with the Zetasizer Nano ZS device. The average Zavg size of selenium particles (583.3±2.6 nm) shows that the new product is micro-sized.

 

- Lines 126-130: The authors mentioned the names of four coating solutions, but did not discuss the method of preparing coating solutions, their chemical composition. How much selenium and how much thyme oil was in the chitosan solution?

Added additional information regarding preparing coating solutions: To prepare spraying solutions, chitosan colloidal solution (500 mg) was dissolved in 20 mL of 1% aqueous acetic acid solution overnight and the mixture was stirred continuously to form a clear solution. On the other hand, 10 mg selenium colloidal solution was dissolved in 10 mL distilled water and kept in a vibrating water bath for 20 min. Selenium colloidal solution was then added into the chitosan colloidal solution and homogenized with continuous stirring. The resulting gel-like viscous solution was poured onto a dust-free ceramic plate and dried at room temperature for 48 hours and then kept in a vacuum oven.

 

- Line 136: what does control mean? Are these uncoated sweet cherries?

This sentence was revised as “Control (uncoated) and coated fruits were kept in two different conditions”

 

- Lines 185-187: Are these two sentences about the reviewer's comments on the manuscript? Why were they included in the manuscript?

These two sentences, which were placed incorrectly, have been deleted.

 

- Line 351: There is no Table 6 in the manuscript.

The term Table 6 is not used in the Line 351.

 

- Figures 3,4,5, 6: The lines representing coated cherry fruits (orange lines) were covered with which of the four coatings: 1. CsMPs (Chitosan colloidal solution); 2. CsMPs+Oil (Chitosan colloidal solution + thyme essential oil); 3. CsMPs+SeMPs (Chitosan colloidal solution + Selenium colloidal solution); 4. CsMPs+SeMPs+Oil (Chitosan colloidal solution + Selenium colloidal solution + thyme essential oil) ? This is unclear.

All figures were redrawn considering the suggestion.

 

- Lines 360-375: The results shown in Figure 4, 5 and 6 are not different (lines overlap). Positive changes are only visible in Figure 3. The conclusion is too general and does not reflect all the results obtained in the study.

The conclusion section was revised.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The manuscript by Yıldız et al. explored applying micro-sized composite edible coatings to extend the shelf-life of sweet cherries， the result showing that CsMPs+SeMPs and CsMPs+SeMPs+Oil can be a potential coating formula for harvest fruit preservation. In my opinion, the manuscript can be accepted after major revision. Please see my comments to improve the manuscript.

-The main problem of this study is it lacks the basic characteristics of the coating, either physical or chemical characterization needs to be performed. Either the appearance of the coating solution, FTIR, or SEM result of the coating should be conducted.

-Line 22-23 and line 25-26, the statement of the significance of extending the fruit's shelf-life is repeated. Only one sentence should be remained.

-Line 30, there is an error in the format of centigrade.

-Line 40-42, the guidance of the study should be deleted.

-Line 55-56, the sentence is unclear please re-write it.

-Line 108, please provide the molecule weight of the low molecular weight of chitosan.

-Line 115-118, the authors should provide more details on synthesizing of micro-particles.

-Line 121-125, the particle size distribution should be a part of the main text otherwise in the supporting material.

-Line 126-130, the authors should provide the formula of each coating solution. There is also a lack of how to prepare the coating solution, just simply physically mix.

-Line 131-134, the authors need to provide the details of the fruit, such as size, weight, color, etc.

-Line 135, how much coating solution was sprayed on each fruit?

-Line 138, what was the relative humanity of the storage?

-Line 139, how many fruit were used in each replicate? How many fruit were picked at each time point for the measurement?

-Line 147-148, what were the criteria of decay? How many fruit were applied to evaluate the decay rate?

-Line 153, the formula of Chroma value has a format error.

-Line 164-167, what were the criteria of significance?

-Table 1, the results should be presented in Mean ± SD or SE.

-Figure 3, all the Y axial should be titled as days after storage. There were no error bars, and data analysis in the figure. It seems like Figure 3 already has the information from Table 1, only one needs to be remained.

-Table 2 and figure 4 have the same problem as Table 1 and Figure 3. It seems like most of the data in Figure 4 do not have significant differences, then the data may be better presented in a table. The authors should provide a picture of the fruit to exhibit the fruit more directly.

-Table 3 and Figure 5, have the same problem. The authors need to double-check the unit of firmness, the reading is generally kg/cm^2, which needs to be converted into Newton by calculating the size of the probe.

-Table 4 and Figure 6, have the same problem.

Author Response

Dear Reviewer 3

Thank you for the suggestions you have made regarding our article. The changes made regarding your suggestions are stated in the article. Corrections in the article are marked in blue

 

- The manuscript by Yıldız et al. explored applying micro-sized composite edible coatings to extend the shelf-life of sweet cherries， the result showing that CsMPs+SeMPs and CsMPs+SeMPs+Oil can be a potential coating formula for harvest fruit preservation. In my opinion, the manuscript can be accepted after major revision. Please see my comments to improve the manuscript.

-The main problem of this study is it lacks the basic characteristics of the coating, either physical or chemical characterization needs to be performed. Either the appearance of the coating solution, FTIR, or SEM result of the coating should be conducted.

FTIR or SEM results of the coating have been added to the Materials and Methods section.

 

-Line 22-23 and line 25-26, the statement of the significance of extending the fruit's shelf-life is repeated. Only one sentence should be remained.

The sentence is deleted.

 

-Line 30, there is an error in the format of centigrade.

The format of centigrade has been corrected.

 

-Line 40-42, the guidance of the study should be deleted.

The sentence is deleted.

 

-Line 55-56, the sentence is unclear please re-write it.

The sentence is deleted.

 

-Line 108, please provide the molecule weight of the low molecular weight of chitosan.

The molecular weight of chitosan is added to in parentheses as “150-250 kDa”

 

-Line 115-118, the authors should provide more details on synthesizing of micro-particles.

Added additional information regarding more details on synthesizing of micro-particles:

For synthesis, chitosan polymer (4 mg/mL) was dissolved in distilled water containing acetic acid (0.1 mL/mL) for 24 hours with stirring. The pH of the solution was then adjusted to 4.6 with 10 N NaOH solution. TPP (2 mg/mL), a surface surfactant, was added to the chitosan medium at a ratio of 1:5 (TPP:chitosan) to prevent aggregation of particles. The TPP solution was added dropwise to the chitosan solution on a magnetic stirrer at 60 °C and the solution was stirred for 3 hours. The resulting products were centrifuged at 12000 rpm for 30 min. The centrifugation process was repeated 3 times by washing with distilled water to remove unbound structures in the medium.

To prepare the tea leaf extract, 50 g of dried tea leaves were boiled with 250 mL of distilled water at 85 °C for 120 min. After cooling at room temperature, it was filtered through Whatman No 1 filter paper and stored at 4 °C for use in the synthesis of Selenium microparticles [31]. For the green synthesis, a 5 mM aqueous solution was prepared with solid selenium (Na₂O₃Se; Sodium Selenite). The extract and aqueous metal solution were mixed in glass beakers at a ratio of 5:3 (extract/metal solution) and allowed to react for about 30 min at room temperature. The formation of selenium particles was determined by measuring the maximum absorbance value in UV-vis spectroscopy at different time intervals within 30 min depending on the color change. After the reaction, the dark solution was centrifuged at 10000 rpm for 5 min, the settled solid was washed several times with distilled water and the final product was dried in an oven at 60°C for 72 hours. The dry fraction was then pulverized using a mortar and pestle and stored for further processing.

 

-Line 121-125, the particle size distribution should be a part of the main text otherwise in the supporting material.

The physical or chemical characterization of particles is added to the Materials and Methods section.

 

-Line 126-130, the authors should provide the formula of each coating solution. There is also a lack of how to prepare the coating solution, just simply physically mix.

Added additional information regarding preparing coating solutions: To prepare spraying solutions, chitosan colloidal solution (500 mg) was dissolved in 20 mL of 1% aqueous acetic acid solution overnight and the mixture was stirred continuously to form a clear solution. On the other hand, 10 mg selenium colloidal solution was dissolved in 10 mL distilled water and kept in a vibrating water bath for 20 min. Selenium colloidal solution was then added into the chitosan colloidal solution and homogenized with continuous stirring. The resulting gel-like viscous solution was poured onto a dust-free ceramic plate and dried at room temperature for 48 hours and then kept in a vacuum oven.

 

-Line 131-134, the authors need to provide the details of the fruit, such as size, weight, color, etc.

Added additional information regarding the details of the fruit: Cherry fruits were dark red in color, long-stemmed, average fruit weight is 7 grams. 

 

-Line 135, how much coating solution was sprayed on each fruit?

The sentence is added: The samples were spray coated to be completely wetted.

 

-Line 138, what was the relative humanity of the storage?

The sentence is added: The conditions in which the fruits were kept were approximately 50-60% humidity.

 

-Line 139, how many fruit were used in each replicate? How many fruit were picked at each time point for the measurement?

The two sentences are added: To determine parameters other than weight loss, samples containing 150 g of fruit with 3 replicates were used separately at each analysis time. The same samples were used at each analysis time throughout the experiment to determine the weight loss. 

-Line 147-148, what were the criteria of decay? How many fruit were applied to evaluate the decay rate?

There is the criteria of decay in the Line 147-148. Approximately 21-22 fruits in the container were used to determine the decay rate. 

 

-Line 153, the formula of Chroma value has a format error.

The formula of Chroma value was revised.

 

-Line 164-167, what were the criteria of significance?

The necessary addition has been made into the sentence.

 

-Table 1, the results should be presented in Mean ± SD or SE.

Tables have been removed from the text.

 

-Figure 3, all the Y axial should be titled as days after storage. There were no error bars, and data analysis in the figure. It seems like Figure 3 already has the information from Table 1, only one needs to be remained.

Tables were removed from the manuscript, leaving only graphs.

 

-Table 2 and figure 4 have the same problem as Table 1 and Figure 3. It seems like most of the data in Figure 4 do not have significant differences, then the data may be better presented in a table. The authors should provide a picture of the fruit to exhibit the fruit more directly.

The pictures are not very descriptive because they are low resolution.

 

-Table 3 and Figure 5, have the same problem. The authors need to double-check the unit of firmness, the reading is generally kg/cm^2, which needs to be converted into Newton by calculating the size of the probe.

Results are presented in Newtons.

 

-Table 4 and Figure 6, have the same problem.

Tables have been removed from the text.

 

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

Lines 179-185: Added detailed description of obtaining coating solutions: 1. CsMPs and 3. CsMPs+SeMPs. How coating solutions 2. CsMPs+Oil and 4. CsMPs+SeMPs+Oil were obtained was not discussed.

The reviewer's remaining comments were incorporated into the new version of the manuscript.

Author Response

Dear Reviewer 2

Thank you for the suggestions you have made regarding our article. The changes made regarding your suggestions are stated in the article. Corrections in the article are marked in green.

*Lines 179-185: Added detailed description of obtaining coating solutions: 1. CsMPs and 3. CsMPs+SeMPs. How coating solutions 2. CsMPs+Oil and 4. CsMPs+SeMPs+Oil were obtained was not discussed.

Reply: For formulations containing essential oil, a 2.5 ml solution of chitosan or selenium was added to 1000 ppm concentrations of thyme essential oil previously dissolved in methanol (40 ml) using a peristaltic pump for 3 minutes at 20,000 rpm to obtain stable dispersions. 

Reviewer 3 Report

Comments and Suggestions for Authors

The authors addressed all the comments and improved the manuscript. In my opinion, it can be accepted in present form.

Author Response

thank you