Influence of Genotype and Environment on Fruit Phenolic Composition of Olive

Round 1

Reviewer 1 Report

The authors studied the impact of genetic and a few environmental factors on phenolic compounds composition in olive fruits. The authors performed ANOVA analyses and concluded that the impact of genotype is more substantial compared to that of environmental factors. The ANOVA analyses should be further refined to confirm this conclusion.

 

In-line comments as below:

 

Line 61-63. Be more specific about the study design. From the description in results, it seems that the ANOVA analysis was performed 1) at two different harvest dates at a single location, 2) between two years at a single location, and 3) at two different locations with the same harvest time. The current description is vague about the conditions.

 

Tables 1 & 2. General formatting comment - use dot instead of comma.

 

Table 2. This table is a bit confusing. Here each row represents the compound from all six cultivars combined. If the purpose is to compare genotype versus component yield, then It would be good to show compound composition for each cultivar. If the results from this table are part of the ANOVA analysis, suggest move the table to supplementary materials. Specify the meaning of "C.V.".

 

Tables 3, 4, & 5. The use of sum of square to determine significance in an ANOVA analysis is not standard, as this value has not been normalized. Look into calculating mean squares and / or F values.

 

Line 162. Comparison of genotypes on two locations – since time of harvest is a factor being investigated in this study, specify the time of harvest for this analysis even if it is not a variable.

Author Response

Thank you so much. Find the attached responses to your comments.

Author Response File: Author Response.docx

Reviewer 2 Report

Dear authors

The following modifications are required:

Abstract

ü  In general, this section is poorly written. It is written simply. This section should include the most important findings from this study. As a result, this section should be improved.

ü  Before describing the goal, the authors must define the issue in a single line and explain why they chose this approach to study this research.

ü  No information about the type of experimental design for studied traits and its component is available in this manuscript.

ü  Some scored data for quantitative traits should be included

ü  In the final line of the abstract, the authors should present a decisive conclusion derived from the research and provide a single line of future prospects.

Introduction

ü  The authors should add some information about the chemical composition of EVOO especially in oil composition.

ü  All abbreviations should be written in full name

ü  No detailed information about the impact of growth and harvest stages on the chemical composition of olive is available

ü  No detailed information about the impact of environmental factors on the chemical composition of olive is available

ü  No detailed information about the impact of genotypes on the chemical composition of olive is available

ü  No detailed information about the impact of the interaction between genotypes and environmental factors on the chemical composition of olive is available

ü  The authors should give some lines about the knowledge gap which their research has covered along with the hypothesis statement

ü  Also, the authors should provide a novelty statement at the end. What new things authors have done or correlated in this research compared to old ones?

ü  The general and specific aim should be inserted

 

Materials and Methods

ü  The physical and chemical data of soil should be added

ü   The name of experimental design should be corrected (Randomized completed block Design). The number of plants per replication should be added

ü  All abbreviations should be written in full name

ü  The units should be added for studied quantitative traits

ü  The age or growth stage of plant and the number of plants or replications for measuring each trait should be provided

ü  No information about the type of experimental design for phytochemical analysis and its component is available in this manuscript.

ü  The comparison between means of different genotypes should be conducted by LSD or Duncan

ü  The name of software used for creating the dendrogram and PCA should be added to the statistical data analysis section

ü  All procedures should be supported by the references

ü  The procedure of the determination of total phenolic compound is not available

ü  The chromatogram of HPLC should be added to the main manuscript

ü  The number of identified is 10 (not 11)

Results and discussion

ü  Data in Figure 1 should be subjected to the statistical analysis (comparison method) such as LSD, Duncan…..

ü  The captions of all Tables and Figures should be detailed

ü  In terms of PCA analysis, it is preferable to create the PCA plot using data from 10 compounds and genotypes. As a result, the groups should be disbanded. Furthermore, the content of the PCA plot should be expanded by including information about the relationship between genotypes as well as genotypes and compounds.

ü  The discussion is weak. The discussion is weak and should be improved because most of the sentences are written as the literature review rather than interpretation of results. The authors should interpret all results obtained in this study by adding some information about the results obtained in their study. The authors should interpret the results of PCA. In this section, the authors should also explain the impact of growth, harvest, and environmental factors on the accumulation of polyphenolic compounds

Conclusion

ü  The authors have written this section in a straightforward manner, and they should conclude the most important findings.

ü  Furthermore, additional works about this research should be added as the future works.

 

 

Extensive correction is needed

Author Response

Thank you so much. Find the attached responses to your comments.

Author Response File: Author Response.docx

Reviewer 3 Report

Revision of the manuscript “Influence of genotype and environment on fruit phenolic composition of olive”.

 

The manuscript I reviewed is a research article focused on evaluating the phenolic composition of olive fruits of 6 different cultivars also evaluating the effect of harvest date, season, and location. Authors analyzed the phenolic extracts by mean of HPLC, identifying 11 phenolic compounds.

In my opinion, the manuscript gives some interesting information, but it also needs several minor and major revisions before publication. Suggestions are listed below.

 

Abstract

Abstract is too descriptive, while any quantitative datum is missing. Authors must add information on the main quantitative data obtained. 

Introduction

The introduction must be better focused on the topic of the manuscript. The first lines are focused on describing the healthy properties of EVOO, but the manuscript is focused on the phenolic compounds of olives.

Authors must add information on which is the state-of-the-art of the phenolic composition of olive fruits (e.g., which phenolic compounds are present? In which amount? Which are the criticisms in analyzing the phenolic compounds of olive fruits?).

In lines 40ff, authors must specify which are the differences between the phenolic compounds present in olive fruits and in olive oil, what happens during the “highly intricate process”, and in which amounts phenolic compounds are transferred from olive fruit to olive oil to the best of the literature knowledge. Otherwise, the sentences reported in this part are too vague and not very informative for the reader.

Finally, and very important, a very few literature manuscripts are cited in the introduction: only 12 manuscripts, with 6 out of them which are self-citations of the authors. Introduction must be strongly improved also under this important aspect, depicting the state-of-the-art also including the studies of other researchers on the topic of the manuscript.

 

·       Line 31: “from other vegetable oils”.

·       Lines 32: “monounsaturated fatty acids”

·       Line 42: citation 6. Why “[No Title Found]”? The title is “Contribution of phenolic compounds to virgin olive oil quality”. Please, correct.

 

Material and methods

·       Line 71: “Most common cultivars” where? In the world, in Europe, in some specific countries?

·       Table 1 and Table 2: please change “,” to “.”.

·       Table 1: what do authors mean with “Total” in the last row? For example, what is “total average temperature”?

·       Lines 91ff: it is well-known that crushing or cutting fresh olives immediately causes enzymatic reactions that lead to a sharp decrease in the content of the main secoiridoids present in the fruit, mainly oleuropein. Olives must be dried (or better freeze-dried) before crushing or cutting them in order to get reliable analytical data. This is one of the main concerns of this manuscript.

·       Line 96: in which step of the extraction process was the internal standard added? Please, specify.

·       Line 99: what type of detector is this? Please specify.

·       Line 102: which were the elution solvents and gradient? Please specify.

·       Line 102: 1 mL/min is a very solvent consuming flow rate. What is the total analysis time? Did authors evaluate using a method needing a lower amount of solvent?

·       Lines 106-106: “hydroxytyrosol-1-glucoside”, “tyrosol-1-glucoside”, “luteolin-7-glucoside” and “apigenin-7-glucoside” should be “hydroxytyrosol-1-O-glucoside”, “tyrosol-1-O- glucoside”, “luteolin-7-O -glucoside” and “apigenin-7-O -glucoside”. Here and throughout the manuscript.

·       Lines 104-109: please, give more details on the approach used for identification of these molecules.

·       Lines 104-106: What about quantitation?

Results and discussion

·       Line 123: “The phenolic compounds were divided into..” Please, correct.

·       Line 125: how was the total phenolic content measured?

·       Table 2: translate “media”.

·       Table 2: it is very surprising that the oleuropein content is not higher than that of ligstroside and demethylligstroside, and that is only slightly higher than demethyloleuropein and rutin. Usually, when olives are correctly treated before analysis, oleuropein is by far the most abundant phenol.

·       Lines 226-228: this is not true. Recent literature showed that oleuropein is by far the most abundant phenols in olive fruits. The results of this research are affected by the treatment of olives before analysis (i.e., cutting of fresh fruit). This aspect must be discussed in the manuscript, and the data must be compared with those of literature manuscripts reporting data from analysis of olives that were not crushed/cut before drying them. The following part of the discussion is correct, with the strong effect of cultivar on demethyloleuropein, which is widely reported in the literature.

·       Line 239-251: again, the output of this manuscript must be compared to other literature, and not only to manuscripts coming from the authors themselves.

·       Lines 252ff: the discussion in this point should keep into account that only two levels of ripening were analyzed, and therefore the results presented give some suggestions but should be confirmed by future research. Please, discuss.

 

Conclusions

This section is very poor.

It seems ok

Author Response

Thank you so much. Find the attached responses to your comments.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

For tables 3, 4 & 5. Suggest correct the titles for these tables to "percentage of sum of square (%)".

Suggest minor editing to correct grammar and typo in certain sentences.

Author Response

Please see the attachment. Thank you. 

Author Response File: Author Response.docx

Reviewer 2 Report

The authors have been addressed all comments

Moderate correction is needed

Author Response

Please see the attachment. Thank you. 

Author Response File: Author Response.docx

Reviewer 3 Report

The authors improved their manuscript based on the reviewers comments, but the manuscript still needs some revisions, as follows.

 

Abstract is still too descriptive. The reviewer is of course aware that the abstract is limited in terms of words, but for example the first 10 lines are focused on the state-of-the-art and the aim of the research, which is not suitable for the abstract section of the manuscript. The abstract still need to be enriched with the main results and findings.

 

The introduction can be further improved, in order to make the manuscript more informative for the reader.

 

Some of my comments to the initial submission have not been sufficiently clarified by authors. Some examples are listed below.

  - Line 99: what type of detector is this? Please specify.

a System Gold 168 detector was used as explained in M&M

Authors did not answer to my question. I guess “System Gold 168” is the model, and not the type of the detector.

 

 - Lines 91ff: it is well-known that crushing or cutting fresh olives immediately causes enzymatic reactions that lead to a sharp decrease in the content of the main secoiridoids present in the fruit, mainly oleuropein. Olives must be dried (or better freeze-dried) before crushing or cutting them in order to get reliable analytical data. This is one of the main concerns of this manuscript.

You are right, that is why longitudinal mesocarp pieces were immediately immersed in a dimethyl sulfoxide (DMSO) solution to avoid further reactions. This protocol has been established and tested in previous works (see Ref 14).

Authors did not answer to my question. The immersion in DMSO is after cutting olives. This operation changes the phenolic profile of the olives, and this must briefly be discussed in the text.

 

 - Line 102: which were the elution solvents and gradient? Please specify.

Solvent A: Phosphoric acid 0.5%

Solvent B: Acetonitrile:Methanol (1:1)

Grandients: 0-25min, 5-30%B; 25-35 min, 30-38%B; 35-40 min, 38% B; 40-45 min, 38-45% B; 45-50 min, 45-100% B; 50-55 min, 100% B; 55-57 min, 100-5% B; 57-60 min, 5% B

This information should be added to the revised manuscript.

Author Response

Please see the attachment. Thank you. 

Author Response File: Author Response.docx