Antioxidant Properties of Tomato Fruit (Lycopersicon esculentum Mill.) as Affected by Cultivar and Processing Method

Round 1

Reviewer 1 Report

Manuscript Number: horticulturae-1732109, titled:

 

Antioxidant properties of tomato fruit (Lycopersicon esculentum Mill.) as affected by cultivar and processing method

 

Review 1 – 6 May 2022

 

Dear Editor of Horticulturae

the argument is interesting and the manuscript is well written. The experiment is well designed and data are well discussed. I suggest to improve the introduction section and to verify some inaccuracies.

 

I suggest a minor revision

 

To the Authors (in detail):

 

1. the argument is interesting and the manuscript is well written. The experiment is well designed and data are well discussed. I suggest to improve the introduction section and to verify some inaccuracies;

 

1. Introduction section, lines 28-31, please insert almost one reference from an International website or publication describing the production of tomatoes in the world and discuss it. For example:  World Processing Tomato Council (WPTC). Or another source. Please, read also (but not only) [X1]:

[X1] https://www.tomatonews.com/en/global-imports-of-tomato-products-updated-february-8-2022_2_1574.html

 

 

1. Introduction section, lines 32-34, support this statement with some proper references. Please use also some International referenced web-site;

 

1. Introduction section, Lines 31-32 or 34-36. Explain that not only the pulp is used but also seeds [X2, X3] and peel [X4] which can be considered a by-product. In addition the tomato seed oil composition was found to be affected by cv [X2, X3] and by processing method (hot-break and cold-break treatments) [X5]. Please, find, read and discuss also these papers, include these references point by point and do not cumulate references at the end of the sentence

 

[X2] Policosanol in Tomato Seed Oil (Solanum lycopersicum L.): the effect of cultivar.

10. Oleo Sci. 64 (6) 625-631 (2015). DOI: 10.5650/jos.ess15002

 

[X3] Sterol composition of tomato (Solanum lycopersicum L.) seed oil: the effect of cultivar.

Int. Food Res. J. 23 (1) 116-122 (2016).

 

[X4] Chemical Composition, functional and biscuit making properties of tomato peel flour.

South Asian J. Food Technol. Environ., 6(1): 874-884 (2020)

DOI: https:doi.org/10.46370/sajfte.2020.v06i01.01

 

[X5]     Tomato seed oil for edible use: cold break, hot break and harvest year effects.

13309. Food Process. Preserv. 2017; 41(12):e13309. https://doi.org/10.1111/jfpp.13309

 

 

1. Introduction section, Lines 48-49, There are many cv of tomato and if you say middle size tomatoes you have not really clarified the quantity for a consumer, please, add the quantity in grams of tomato and the name of some cultivar as an example including some proper reference. Please, specify;

 

1.  Lines 58-59, please, detail which treatments and insert some proper references;

 

1. M&M section: describe the cultivars you have studied in this experiment. No information is given;

 

1. Line 99 and in the whole manuscript, please, separate: 3 g and not 3g;

 

1. Line 111 and in the whole manuscript, when you indicate a temperature, separate the numeric value from the symbol: 99-100 °C and not 99-100°C;

 

1. Line 115, verify and correct the symbol of temperature: °C;

 

1. Line 121, replace in darkness with in the dark;

 

1. Line 150 and in the whole manuscript, decide if you want to use l or L as abbreviation for liter;

 

1. Line 162 and in the whole manuscript: µl or µL?

 

1. Caption of table 1 (p), M&M section (P), and in the whole manuscript, please, when you describe the significance use always the same criterion;

 

1. References section, please, be consistent with the instructions for authors of Horticulturae, for example, the journals’ names have to be abbreviated (see refs 12, 14, 15, 19 and so on);

 

1. References section: the issue number is not required. (see also ref 13);

 

1. Please, write in blue color or evidence differently the corrections you will do

I suggest a minor revision

Regards.

 

Comments for author File: Comments.pdf

Author Response

Dear reviewer,

as attached you may find the answers to your questions and recommandations. Thank you very much for your valuable help. Warm regards Anna Keutgen

Author Response File: Author Response.docx

Reviewer 2 Report

Antioxidant properties of tomato fruit (Lycopersicon esculentum Mill.) as affected by cultivar and processing method

I am going to evaluate this MS from my specialty “plant nutrition and soil science”!

Although, this MS has a great part in food technology and processing but the quality of producing tomato mainly depends on nutrition and cultivation of the plant?

What we feed to cultivated plants, mainly will impact their quality??

About the novelty, I found some published articles similar like

De Souza et al. (2020). Bioactive compounds and antioxidant activity in tomatoes (Lycopersicon esculentum L.) cultivars in natura and after thermal processing

General comments:

1- Not accepted Abstract, it should include all articles parts in brief, as 2 main sections: first include the importance of this topic and how did the experiment carry out?

Second part: the most important findings in the study? Then the expected or further studies?

2- Keywords: please do not repeat any word already mentioned in the title??

3- Many refs. In introduction sections need to be updated for sure!

4- 2. Materials and Methods sections, not accepted to write 2.1. Material even in plural, which material? You can write plants materials or selected cultivars, etc.??

Why authors used these cultivars? Where the main properties of these cultivars? Are there any differences among them? Definitely, these properties are essential for the interpretation of your results!!!!

5- The used soil, where its characterization from texture, available nutrient contents, pH, EC, etc.!!!

6- How did authors apply fertilizers and irrigation during the study??

7- it is recommended to draw a flowchart for your study, what is the start, with aim till the final measurements???

8- Please do not write the cultivars as ‘Rilia’, please just names??

9- the calculation of Losses of ascorbic acid and other bioactives in tomato cultivars mush explain in the Materials and Methods section

10- I can expect a table survey includes a comparison between different cultivars of tomato from different places all over the world using the measured parameters. This table should explain the main factor controls these parameters. May be different methods of processing and their technology are important as well!

11- in conclusion section, the authors mentioned

“Both, the content of bioactive compounds and the antioxidant capacity depended on cultivar and processing”

Yes, but where the environmental conditions or stress, nutrients and their availability to cultivated plants, and agricultural practices?

So, in the end of the conclusion, author should add what are the further studies?  

Where the redocumentations from this study?

This study needs major revision

 

Author Response

Dear reviewer,

as attached you may find the answers to your questions and comments. Thank you very much for your valuable help. Kind regards Anna Keutgen

Author Response File: Author Response.docx

Reviewer 3 Report

The manuscript entitled " Antioxidant properties of tomato fruit (Lycopersicon esculentum Mill.) as affected by cultivar and processing method" requires some major comments and considerations:

• In the Introduction, the Authors provided information on the chemical composition of  L. esculentum, but in my opinion, this issue is too briefly presented. Therefore, I suggested that more information and references about types of isolated polyphenols of subjected L. esculentum should be included in the Introduction.
• In the manuscript, the methods used to study the content of polyphenols and antioxidant activity in tomato varieties and the methods of their processing are insufficient.
• The antioxidant capacity needs different methods to obtain significant  and relevant results.
• In addition, the polyphenols were quantified by the Authors only by spectrophotometric methods. It is well known that this type of analysis is not very precise, and the results obtained are mostly overstated. To have an exhaustive polyphenol profile, the quantitative data should be completed by adding HPLC-PDA or HPLC-PDA-MS results for tomato samples. After performing the LC-MS analysis, one might tell which polyphenols are the main determinants of the declared activity. So I encourage the Authors to complete their work with the results of chromatographic methods, which are so commonly and routinely used nowadays. 

Author Response

Dear reviewer,

as attached you may find the answers to your questions and comments. Thank you very much for your valuable help. Kind regards Anna Keutgen

Author Response File: Author Response.docx

Reviewer 4 Report

This study is aimed to investigate the changes in the antioxidant activity and selected phytochemical composition indices (lycopene, ascorbic acid and total phenolic content) of 9 tomato cultivars and tomato processing products (puree and ketchup).  This study provides relevant information for the tomato processing industry, however there are specific comments addressed to the authors, which should be clarified prior to the further steps of publishing.

1. Authors should clearly indicate the novelty of this research in the introduction.
2. Lines 17-18, Lines 436-438. The statement that ‘Heating enhanced the content of lycopene and total phenolics, resulting in an increment of antioxidant capacity, despite the reduction of ascorbic acid’ is misleading, since only one set of pasteurization temperature/time was applied (90-100°C/ 15 min) to produce tomato products. In order to support such statements (all over the manuscript) authors should test the antioxidant activity and phytochemical composition changes under the different thermal load conditions.
3. Line 20. Authors should explain the abbreviation ‘FM’ in the abstract.
4. Lines 18-20. The statement that ‘Conducted experiments revealed that cultivars such as ‘Vyta’ and ‘Cima’ are well suitable for industrial purposes due to their high dry matter content of more than 9% FM and high biological value’ is misleading, since a very limited number of phytochemical composition indices were determined in order to justify higher biological value of particular cultivars.
5. Lines 20-22. The statement that ‘With respect to serving size, the best sources of antioxidants and antioxidant capacity were fresh tomatoes followed closely by tomato puree irrespective of cultivar’ is misleading, especially taking into consideration the above provided information that heating enhances the antioxidant capacity of fresh tomatoes.
6. Lines 113-115, Lines 296-300, Lines 375-380, Figures 3 and The composition of ketchup indicates the presence of other bioactive constituents’ sources (onion pulp, garlic pulp), which even at low percentages will contribute to the overall antioxidant potential of ketchup samples. Therefore, authors should measure the antioxidant capacity of these additives alone (prior and after the thermal treatment) in order to determine the impact of the additional tomato puree heating towards the increasing antioxidant potential of ketchup (or maybe these effects are achieved mainly due to the addition of antioxidant-rich additives?). Also, the analysis of the so-called ‘blank’ ketchup sample (double-heated tomato puree without additives) would be relevant in order to justify statements presented in Lines 375-380.
7. Line 239. The statement that ‘The lycopene content of tomato cultivars depends on the processing method’ is misleading, since any compound content in cultivars depends from the properties of those cultivars, growing conditions, etc. The processing method might influence the content of particular substance in the final product, but not in cultivar.
8. Lines 266-268. The provided statements are contradicting the major conclusion of the manuscript that heating increases the antioxidant capacity due to the enhanced lycopene content (Lines 17-18, Lines 436-438). Also, since he analysis of the so-called ‘blank’ ketchup sample (double-heated tomato puree without additives), was not performed, statements in Lines 266-268 are not justified experimentally. Also, did authors took into consideration the percentage of tomato puree in the ketchup (65%, Line 113)? For example, Table 1 reports 152 mg/kg of lycopene in ‘Roma’ ketchup, which amounts ~61% of the reported puree value (~250 mg/kg) of the same cultivar.

Author Response

Dear reviewer, as attached you may find the answers to your questions and comments. Thank you very much for your valuable help. Kind regards Anna Keutgen

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

Please change 2.1 Plants Materials to 2.1 Plant Materials (only last word with “S”)

This is not real soil, use please the “growing media” is the write word???

About the “flowchart” it is very important t summarize your work to readers

Please add the “flowchart”!!

About the “table survey” it would be so nice to insert in your original article, please!!!

This table will make your work stronger, please!

About the “Where the redocumentations from this study?

Sorry, I mean the general recommendations from your work?

This needs a minor revision

Author Response

Dear reviewer,

Thank you very much for the anew revision of the manuscript and further comments for improving the manuscript. Below you have a transcription of the realisation of your recommendations (green background in manuscript).

Kind regards

Respectfully

Anna Keutgen

 

1. Please change 2.1 Plants Materials to 2.1 Plant Materials (only last word with “S”)

Done

2. This is not real soil, use please the “growing media” is the write word???

The word “soils” is replaced by “substrate”

3. About the “flowchart” it is very important t summarize your work to readers

Please add the “flowchart”!!

The flowchart is added as recommended. The numbering of the figures is changed due to the new presentation.

4. About the “table survey” it would be so nice to insert in your original article, please!!!

This table will make your work stronger, please!

Dear reviewer, such a table is a good idea but it is really a very big review work to consider a comparison between different cultivars of tomato from different places all over the world using the measured parameters (there are about 3,800 registered cultivars) and the growing possibilities, growing and climatic conditions, field and greenhouse production, nutrition regimes, watering or fertigation, kind of fertilizers etc.), so it is actually not possible, especially not in an original research paper.

5. About the “Where the redocumentations from this study?

Sorry, I mean the general recommendations from your work?

The recommendation is to use the cvs Cima and Vyta, because of their high technological quality. It is already mentioned in the conclusions.

Reviewer 3 Report

Unfortunately, none of my comments were accepted by the Authors. Even the request to supplement the polyphenols content in tomatoes in the introduction was not approved by the Authors. The Authors write that "... elucidating the polyphenol composition was not within the scope of the study/manuscript" However, the polyphenol level, determined only by the spectrophotometric method, was one of the accepted parameters for the evaluation of the variety and processing method of tomatoes.

The article was entitled "Antioxidant properties of tomato fruit .....". However, only one method was chosen to evaluate the antioxidant properties of tomatoes. The Authors write that "Concerning the antioxidant activity, we are aware of the fact that different methods exist, yet we have selected the one that in our opinion is most suitable." A variety of antioxidant assays based on hydrogen atom transfer (HAT) and/or single electron transfer (SET) reaction mechanisms have been widely employed for quantification of antioxidant capacity of plant samples. Still, there is no universal assay that can accurately reflect all the antioxidants in a complex system. So what was the justification for choosing only the ferric reducing antioxidant power (FRAP) test?

 

Author Response

Dear reviewer,

you comments are very valuable and as mentioned in the next investigations focusing on the polyphenolics in tomato and its products we should cleary concentrate on the individual phenolic components. About the question regarding choosing FRAP: it is commonly used for the investigation of the antioxidant capacity of polyphenols containing food (all plant products). It is here actually not a contradiction, the total content of polyphenols was determined and their contribution to the FRAP, beside the other compounds, was evaluated. Of course, it is clear that FRAP is describing in the first line the water soluble compounds, but not exclusively. Because the aim of the research was the evaluation of the contribution of tomato and tomato product to the antioxidant pool in the human diet and the meaning to the human health, the FRAP as a measure of the ferric reducing ability of plasma by humans was chosen, just to have a general information about the conversion and usage in the human body (at least potentially). Of course, there are some limitations of it, it is an estimation and not a measurement of the blood of the kohort of the patients. This was the decision to chose FRAP.

Kind regards

Anna Keutgen

Reviewer 4 Report

The authors provided adequate answers to the reviewer's questions and introduced majority of the suggested corrections in the manuscript.

Author Response

Dear reviewer,

thank you very much for anew and positive assesment.

Kind regards

Anna Keutgen