Effect of Temperature and Storage Time on Some Biochemical Compounds from the Kernel of Some Walnut Cultivars Grown in Romania
Round 1
Reviewer 1 Report
Horticulturae
Effect of temperature and storage time on some biochemical compounds from the kernel of some walnut cultivars grown in Romania
In this work, the authors aimed to analyze the kernel`s quality, by the determination of Total Phenolic Content, Total Tanin Content, Total Flavonoids Content, lycopene, and β-carotene were analyzed of 8 walnut cultivar grown in Romania, regarding the effect of temperature and storage period.
They consider three different temperatures (the freezer (very low-temperature treatment), refrigerator (low-temperature treatment), or was stored at room temperature) and three storage periods (short medium and long term)
They observed that In general, the phenolic and carotenoid compounds followed opposite trends during short-term storage, and in some cases in medium-term storage. On long-term storage, in both cases, there was a reduction in concentration, more pronounced for carotenoids. The most efficient method for preserving walnut kernel concerning their phenolic content was freezing, and in the case of carotenoids, keeping them at room temperature assured the smallest losses. Depending on the walnut cultivar, the preservation of the walnut kernel can be extended to 5 months, by storage at -18 °C without loss of phenolic compounds, and a period shorter than 5 months (but certainly longer than 3 months) could be recommended for storage at 4 °C. Keeping it at room temperature can be an option for a short period of about 3 months. None of the preservation methods are adequate if the losses recorded for carotenoids are taken into account.
The manuscript was interesting to read but, in my opinion, it should not be suitable for publication in its present form. The results are interesting but are not presented in a clear and concise manner.
The statistical analysis that should be used is a two-way ANOVA (temperature x storage time), then the authors also could observe if there are any interactions between treatments.
In table 1. Should include the values for December. And include also the statistic at this point
Author Response
Author's Reply to the Review Report (Reviewer 1)
The authors thank you for the patience with which you analyzed our work and for the advice you offered!
Comments and Suggestions for Authors
Effect of temperature and storage time on some biochemical compounds from the kernel of some walnut cultivars grown in Romania
In this work, the authors aimed to analyze the kernel`s quality, by the determination of Total Phenolic Content, Total Tanin Content, Total Flavonoids Content, lycopene, and β-carotene were analyzed of 8 walnut cultivar grown in Romania, regarding the effect of temperature and storage period.
They consider three different temperatures (the freezer (very low-temperature treatment), refrigerator (low-temperature treatment), or was stored at room temperature) and three storage periods (short medium and long term)
They observed that In general, the phenolic and carotenoid compounds followed opposite trends during short-term storage, and in some cases in medium-term storage. On long-term storage, in both cases, there was a reduction in concentration, more pronounced for carotenoids. The most efficient method for preserving walnut kernel concerning their phenolic content was freezing, and in the case of carotenoids, keeping them at room temperature assured the smallest losses. Depending on the walnut cultivar, the preservation of the walnut kernel can be extended to 5 months, by storage at -18 °C without loss of phenolic compounds, and a period shorter than 5 months (but certainly longer than 3 months) could be recommended for storage at 4 °C. Keeping it at room temperature can be an option for a short period of about 3 months. None of the preservation methods are adequate if the losses recorded for carotenoids are taken into account.
The manuscript was interesting to read but, in my opinion, it should not be suitable for publication in its present form. The results are interesting but are not presented in a clear and concise manner.
The statistical analysis that should be used is a two-way ANOVA (temperature x storage time), then the authors also could observe if there are any interactions between treatments.
Answer: The statistical analysis has been realized according to your suggestion but the significant influence of the cultivar was found. So, has been performed to check the interactions between the three factors (cultivar, storage type, and storage time) by Three-Way Analysis of Variance (ANOVA) and Interaction Plot Graphs. Significant three-way interaction effects have been obtained (P<0.05) in the case of TPC, TFC, TTC, Lycopene, and β-carotene content determinations. Tables with Analysis of Variance (Tables S1–S5) and Interaction Plot Graphs (Figures S1–S5) are attached as Supplementary Materials. In the interaction plot graphs, the lines are not parallel and this type of interaction effect indicates that there is a relationship between cultivar, storage type, and storage time regarding TPC, TFC, TTC, Lycopene, and β-carotene contents.
In table 1. Should include the values for December. And include also the statistic at this point
Answer: Table 1 contains the values for December and the statistics for this moment.
Thank you for your input in improving the manuscript.
Author Response File: 
Author Response.docx
Reviewer 2 Report
Line 222, Why you use gallic acid as the standard for the determination of polyphenols? Why not use EGCG? Tannic acid or proanthocyanidins?
Line 233, Why you use catechin as the standard for the determination of flavonoid content? Why not use rutin or quercetin?
Results and discussion section
All the results and discussion section, the author repeatedly describes the data that can be read out in the figures with words, but lacks the analysis and discussion on the scientific law presented by the data in the figures, the scientific phenomenon explained by the scientific law, the scientific reasons behind the scientific phenomenon, and the potential application of the scientific results. Therefore, I suggest that the author should attach great importance to this problem in your revision and make substantive improvement.
Special comments
1) In your methods section, many descriptions about your determinations are not well. The description of the experimental method section needs to enable the reader to repeat your experiment. So, You need to give the necessary steps and information, especially necessary procedures and important parameters.
2) The descriptions for “results” were more, and the discussions were so limited and simple. The appropriate discussion and explain about the scientific phenomenon and potential applications should be added. So, I suggest that you should add some useful discussions to give the more value about your research results.
3) In its current state, the level of English throughout your manuscript does not meet the journal's desired standard. There are a number of grammatical errors and instances of badly worded/constructed sentences. Please check the manuscript and refine the language carefully. I suggest that you should ask several colleagues who are skilled authors to check the English before your submission.
Author Response
Author's Reply to the Review Report (Reviewer 2)
The authors thank you for the patience with which you analyzed our work and for the advice you offered!
Comments and Suggestions for Authors
Line 222, Why you use gallic acid as the standard for the determination of polyphenols? Why not use EGCG? Tannic acid or proanthocyanidins?
Answer: Indeed, gallic acid is not the major polyphenol in the walnut kernel, but it is among the most abundant polyphenols in the walnut. In addition, some authors reported the content of walnuts in polyphenols as mg GAE 100 g-1.
Line 233, Why you use catechin as the standard for the determination of flavonoid content? Why not use rutin or quercetin?
Answer: The specialized literature reports catechin as the major flavonoid in the walnut kernel, which justifies its choice as the standard for determining the flavonoid content.
Results and discussion section
All the results and discussion section, the author repeatedly describes the data that can be read out in the figures with words, but lacks the analysis and discussion on the scientific law presented by the data in the figures, the scientific phenomenon explained by the scientific law, the scientific reasons behind the scientific phenomenon, and the potential application of the scientific results. Therefore, I suggest that the author should attach great importance to this problem in your revision and make substantive improvement.
Answer: We have modified the results and discussion section according to your suggestion. Thank you for the advice!
Special comments
1) In your methods section, many descriptions about your determinations are not well. The description of the experimental method section needs to enable the reader to repeat your experiment. So, You need to give the necessary steps and information, especially necessary procedures and important parameters.
Answer: The methods were presented in detail, indicating the principle of the method, obtaining the extracts, and the working method for the determination of the analyzed parameters.
2) The descriptions for “results” were more, and the discussions were so limited and simple. The appropriate discussion and explain about the scientific phenomenon and potential applications should be added. So, I suggest that you should add some useful discussions to give the more value about your research results.
Answer: This chapter has been completed, discussing the results obtained and presenting the potential applications, and the statistical analysis has been conducted according to your and other reviewers' suggestions.
3) In its current state, the level of English throughout your manuscript does not meet the journal's desired standard. There are a number of grammatical errors and instances of badly worded/constructed sentences. Please check the manuscript and refine the language carefully. I suggest that you should ask several colleagues who are skilled authors to check the English before your submission.
Answer: We tried to correct the mistakes and asked for the help of an English connoisseur.
Thank you for your input in improving the manuscript.
Author Response File: Author Response.docx
Reviewer 3 Report
The manuscript by Vijan et al. reports the effects of temperature and storage time on the content of selected bioactive compounds in walnut kernels grown in Romania. In my opinion, the work does not meet the criteria to be published in Horticulturae journal, and I therefore suggest rejection.
The authors performed routine spectrophotometric analyses. The results would be more representative if the individual phenolic compounds had been identified and measured by the HPLC method during the storage time. In addition, the authors pointed out that the aim of their study was to monitor the kernel’s quality under certain conditions. What about the content of lipids, proteins, dietary fibre, and other nutritional parameters (as mentioned in the Introduction section)?
Minor comments:
Line 41 Vitamin F is also called essential fatty acids (old nomenclature), the previous line has already said ‘polyunsaturated fatty acid (omega 3 and omega 6)’
Lines 44-53 Unnecessary for the already long Introductory section, which should be shortened generally.
Lines 59-61; 64-66 Appropriate reference(s) should be cited.
Author Response
Author's Reply to the Review Report (Reviewer 3)
The authors thank you for the patience with which you analyzed our work and for the advice you offered!
The manuscript by Vijan et al. reports the effects of temperature and storage time on the content of selected bioactive compounds in walnut kernels grown in Romania. In my opinion, the work does not meet the criteria to be published in Horticulturae journal, and I therefore suggest rejection.
The authors performed routine spectrophotometric analyses. The results would be more representative if the individual phenolic compounds had been identified and measured by the HPLC method during the storage time. In addition, the authors pointed out that the aim of their study was to monitor the kernel’s quality under certain conditions. What about the content of lipids, proteins, dietary fibre, and other nutritional parameters (as mentioned in the Introduction section)?
Answer: The HPLC method is a representative analytical method for the separation, identification, and dosage of individual compounds and many papers are published in the literature that presents the individual phenolic compounds in walnut kernels. Also, numerous papers present the lipids, proteins, and dietary fiber content of walnut kernels stored under different storage conditions at different time points. Considering these known data, we proposed to analyze the behavior of some Romanian and foreign walnut varieties grown in Romania, regarding the effect of temperature and storage period on the quality of the walnut core, by determining the content of some bioactive compounds (polyphenols, flavonoids, tannins, lycopene, and β-carotene), with a major impact on health. The literature study showed us that the evolution over time of these bioactive compounds in this natural functional food has not been sufficiently investigated, finding few reference works, some of which are even by the authors of the present study.
Minor comments:
Line 41 Vitamin F is also called essential fatty acids (old nomenclature), the previous line has already said ‘polyunsaturated fatty acid (omega 3 and omega 6)’
Answer: Thank you! We corrected.
Lines 44-53 Unnecessary for the already long Introductory section, which should be shortened generally.
Answer: Thank you! I shortened the introduction.
Lines 59-61; 64-66 Appropriate reference(s) should be cited.
Answer: Thank you! I have added the appropriate references.
Thank you for your input in improving the manuscript.
Author Response File: Author Response.docx
Reviewer 4 Report
The topic of the article and content is relevant for nut growers and scientists. Experimental design and methodology were arranged appropriately, but some mistakes were pointed out to fix.
Line 191-196. I suggest not writing the name of the month until the nuts were stored, but the storage time. It would be clearer if it was written that nuts were stored for 2 months, etc.
Specific storage temperature must be specified, not enough to write „...in the freezer (very low-temperature treatment, VLTT), refrigerator (low-temperature treatment, LTT), or was stored at room temperature (RTT).“
If the nuts were kept frozen, how were the samples were prepared? They must have been thawed. So, specify sample preparation conditions.
Need to state what wavelength was used to determine tannins.
Line 261-262 „All analyses were performed in three replicates. Practically, the extracts necessary for the determination of TPC, TTC, TFC, lycopene, and β-carotene were analyzed in triplicate at each moment of analysis.“ This information is not related to section „2.4. Statistical analysis“. Should be moved to section 2.3.
TPC, TTC, TFC - these abbreviations should be explained in the text.
3. Results and Discussions
The division of the chapter into subsections should be reconsidered, why does occur only "3.1. Analysis of TPC variation depending on temperature and storage time"? The results analysis up to this subsection must also be described by some subsection name.
„3.1. Analysis of TPC variation depending on temperature and storage time“. „3.2. Analysis of TFC variation depending on temperature and storage time.“ „3.3. Analysis of TTC variation depending on temperature and storage time“. „3.4. Analysis of the variation of lycopene and β-carotene depending on temperature and storage 456 time“. The name of the subsections needs to be clarified. „... depending on storage temperature and time“?
The information in Figures 1,2, 3, 4 and 5 is inaccurate. Now without text information, it is understood that nuts were stored in March, May or June. It would be clear if were written that the nuts were stored for 2 months, 4 months, etc.
What does mean „Lycopene“ in Figure 4 and β-carotene in Figure 5?
Author Response
Author's Reply to the Review Report (Reviewer 4)
The authors thank you for the patience with which you analyzed our work and for the advice you offered!
The topic of the article and content is relevant for nut growers and scientists. Experimental design and methodology were arranged appropriately, but some mistakes were pointed out to fix.
Line 191-196. I suggest not writing the name of the month until the nuts were stored, but the storage time. It would be clearer if it was written that nuts were stored for 2 months, etc.
Answer: Thank you! We have modified it according to your suggestion.
Specific storage temperature must be specified, not enough to write „...in the freezer (very low-temperature treatment, VLTT), refrigerator (low-temperature treatment, LTT), or was stored at room temperature (RTT).“
Answer: Thank you! We have modified it according to your suggestion.
If the nuts were kept frozen, how were the samples were prepared? They must have been thawed. So, specify sample preparation conditions.
Answer: Thank you! We specified the conditions for the sample preparation.
Need to state what wavelength was used to determine tannins.
Answer: Thank you! We specified the wavelength used for the determination of tannins.
Line 261-262 „All analyses were performed in three replicates. Practically, the extracts necessary for the determination of TPC, TTC, TFC, lycopene, and β-carotene were analyzed in triplicate at each moment of analysis.“ This information is not related to section „2.4. Statistical analysis“. Should be moved to section 2.3
Answer: Thank you! We moved this information to section 2.3.
TPC, TTC, TFC - these abbreviations should be explained in the text.
Answer: Thank you! The abbreviations TPC, TTC, and TFC were introduced in section 2.3, before the first time of being used in the text.
- Results and Discussions
The division of the chapter into subsections should be reconsidered, why does occur only "3.1. Analysis of TPC variation depending on temperature and storage time"? The results analysis up to this subsection must also be described by some subsection name.
„3.1. Analysis of TPC variation depending on temperature and storage time“. „3.2. Analysis of TFC variation depending on temperature and storage time.“ „3.3. Analysis of TTC variation depending on temperature and storage time“. „3.4. Analysis of the variation of lycopene and β-carotene depending on temperature and storage time“. The name of the subsections needs to be clarified. „... depending on storage temperature and time“?
Answer: Thank you! We have renamed the subsections in the Results and Discussion chapter.
The information in Figures 1,2, 3, 4 and 5 is inaccurate. Now without text information, it is understood that nuts were stored in March, May or June. It would be clear if were written that the nuts were stored for 2 months, 4 months, etc.
Answer: Thank you! We have modified it according to your suggestion.
What does mean „Lycopene“ in Figure 4 and β-carotene in Figure 5?
Answer: Thank you! We have corrected, specifying lycopene and β-carotene content.
Thank you for your input in improving the manuscript.
Author Response File: Author Response.docx
Round 2
Reviewer 3 Report
The revised version of the manuscript has been improved. I suggest its acceptance after minor revision:
- The quality of all Figures should be improved (high resolution)
