High-Relative-Humidity Storage Reduces the Chilling Injury Symptoms of Red Sweet Peppers in the Breaker Stage

Round 1

Reviewer 1 Report

The manuscript of Afolabi et al. describes the application that the high RH storage can effectively reduce CI symptoms in sweet pepper. Although the general concept and experimental design involving this study are not innovative, there are a few lines of novel findings which could be concluded from this research. Overall, this manuscript is well organized, and the new discoveries will provide valuable insights into the postharvest storage of sweet pepper. Some phrases in the manuscript are still required to be defined or adjusted before publication. Several points need to be clarified or revised.

1. I suggest that the title of this manuscript need to be reconsidered or delete “Breaker Stage”.

2. Subtitles in ‘3. Results and Discussion’ are like that in ‘2. Materials and Methods’ 

3. Phenotype images should better be offered.

4. Abstract, ‘Finally, breaker stage peppers stored at high RH showed less chilling than red-ripe peppers stored at low RH.’ is logistically not meaningful because of double variant. 

Author Response

Thank you for your comments. Corrections are in the attached file.

Author Response File: Author Response.pdf

Reviewer 2 Report

This study explored the effect of relative humidity (RH) on the chilling injury of sweet pepper under low-temperature storage. Based on the analysis of the water loss rate, calyx browning index, electrolyte leakage, MDA, respiration rate, DPPH antioxidant activity and vitamin C, higher RH could reduce the CI of sweet pepper under low-temperature storage and maintain good quality. The topic of this study aims to solve the industrial problem and the research design is appropriate, but I think there are still some deficiencies in the result analysis and manuscript writing, which need to be modified and improved.

The main comments are as follows:

1.        Chilling injury of sweet pepper was the focus of this study. It was mentioned in the introduction that the CI symptoms mainly include surface pitting, shrivelling, and calyx browning etc. Compared with the bar charts and tables, phenotypic pictures can more directly reflect the differences in treatment and the marketability of fruits after storage. So the phenotypic pictures are suggested to be supplemented in the manuscript.

2.        High humidity during storage may lead to the increase of fruit decay; whether a related phenotype was observed in this study, it is recommended to supplement the decay rate data.

3.        The English writing of this manuscript needs to be modified and improved. In addition, the discussion and results are combined, while in discussion, the author simply summarized the previous studies as whether they are consistent with the results of this study. Such as in line 168, ‘This observation is also similar to what was reported for sweet peppers harvested at the same stages in another experiment [22]’; in line 186 ‘This result agrees with the positive correlation found between weight loss and CI [13]’. It does not reflect the new findings and views of this study, so it is suggested to be supplemented.

4.        The writing in the article is not standard, many places make me confused, such as in line 171, 357 ‘water loss rates’ and in line 174, 363 ‘weight loss rate’ should be unified.

5.        In section 3.2, ‘gas production rates’ represent the ‘ethylene production rates’ or ‘respiration rate’?  In line 214-215, ‘they promote the accumulation of aberrant chemicals such as malondialdehyde (MDA)’, why the MDA was called aberrant chemicals, and how it affects CI symptoms? In line 215-217,’These cold-induced gases have been shown to be produced based on the degree of damage that occurs to the fruits after they are transported to ambient conditions rather than during cold storage’, why these gases were called cold-induced gas, Instead, the production of these gases is induced at low temperatures.

6.        Many inferences about the results in the article are based on insufficient evidence. It is suggested to supplement with more adequate reference basis, or reduce the uncertainty of the inference. Such as in line 306-310, about the Soluble sugars with ROS.

7.        According to the statistical analysis, the soluble sugar and fruit firmness showed no significant difference between different treatments, so it is suggested to simplify the description and inference about these two parts.

8.        Based on the description of the material method, I inferred that 5,10 and 15d in Figure 1 represent the days under low temperature, without transferring to ambient temperature. If so, it is suggested to mark the low temperature at these sample times, and mark the ambient temperature at 18d and 20d to distinguish.

9.        In line171, the cited figure should be figure 3B (not figure 4B), but the figure in the manuscript should be placed based on the cited order, and it is suggested to adjust.

10.    The legend in Figure 2 is wrong.

11.    The color of the bar in figure 3 is wrong.

12.    The format of references is not standard, and the format of journals is not uniform.

Author Response

Thank you for your comments and suggestions. Attached file contains the corrections and suggestions.

Author Response File: Author Response.docx

Reviewer 3 Report

This manuscript investigates the effect of high relative humidity on chilling injury of sweet peppers at breakage and red ripening stages, the results of the study are of guidance in solving the problem of cold damage to peppers in the industry. But some presentation and data display problems that need to be carefully revised to make it both accurate and understandable.

These are some comments:

1.      In line 34, replace ‘fruits’ with ‘peppers’

2.      For the measurement of respiration and ethylene production rates (lines 96-106), the samples used to measure respiration and ethylene production rates were the same, so the treatment of the samples to collect the gas should be placed at the beginning of the method. In addition, the formula for ethylene calculation should be added.

3.      In lines 128-129, the author should explain why the number of peppers used in the experiment was different at the beginning and at the end, does it only the last day that the number of peppers measured was 5 and the other time points were 10? 

4.      Is the experiment using a red or green sweet pepper variety? If it is a red sweet pepper, it should be reflected in the manuscript material and title.

5.      It is suggested that the 18 and 20 d in the figures change to 15+3 d and 15+5 d, table 1 ‘Initial’ change to ’0 d’, ‘After cold storage’ change to ’15 d’, ‘3rd day in ambient conditions’ and ‘5rd day in ambient conditions’ change to 15+3 d and 15+5 d, to make it easier to distinguish cold storage and ambient storage. Other figures and tables are modified with reference to this opinion.

6.      Did the author forget to fill the color of the fifth bar in the Figure 3B?

7.      In the abstract, the author said ‘Finally, breaker stage peppers stored at high RH showed less chilling than red-ripe peppers stored at low RH.’, but according to Figure 1, both weight loss and CI index show that red ripe peppers are similar to breaker stage peppers, but calyx browning index showed that red ripe peppers were lower and the effect was better than breaker stage peppers. Therefore, I think the conclusion needs to be modified.

8.      Why did the authors choose only two humidity environments, 98% and 70%, when the appropriate humidity for most fruits and vegetables is 90%-95%? If the industry uses 98% humidity to store large quantities of peppers, although the problem of cold damage is solved, high humidity does promote disease development, how to balance this contradiction?

9.      The conclusion is not abstract and does not need to introduce context, but only to summarize the findings and make the corresponding conclusions, so the writing of the conclusion section needs to be reworked.

10.  In my opinion, the final conclusion of this study should be as follows: Integrating the cold damage index, quality index and antioxidant index, this study advocates the harvesting of sweet peppers at the color-breaking stage for subsequent high-humidity cold preservation compared to the traditional cold preservation of sweet peppers at the red ripening stage.

11.  The writing of the ‘Results and Discussion’ section of the manuscript still needs improvement.

Author Response

Thank you for your comments and suggestions. Attached file contains corrections and suggestions. Thank you.

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

     The author replied to my comments carefully and made reasonable revisions to the manuscript. The revised manuscript is satisfactory.