Antioxidant Capacity and Shelf Life of Radish Microgreens Affected by Growth Light and Cultivars

Round 1

Reviewer 1 Report

Manuscript ID: horticulturae-2078102

Title: Antioxidant capacity of radish microgreens after storage: influence of growth light

Authors: Selma Mlinarić, Antonija Piškor, Anja Melnjak, Alma Mikuška, Martina Šrajer Gajdošik and Lidija Begović

 

The authors present interesting work about different radish microgreens that have beneficial effects on human health due to different antioxidant compounds they accumulate in response to distinct light quality irradiance. The authors compare biochemical parameters of the three microgreens after harvest and 3, 7 and 14 days after storage at 4oC. To be published, the work needs to be much improved and totally reorganized, it needs to be rewritten.

Comments:

Introduction section is well written. M&M are described precisely.

Main concerns:

1) Results and Discussion section: Description of the results is very chaotic. First, the authors present the control plant results. After some lines of discussion they describe the results after 3, 7, and 14 days at 4oC followed by another discussion of those results. The only result described properly is the Dry Mass content (Line 375-393). Please, describe all other results this way as Dry mass content – Control plants results, 3, 7, and 14 d after harvest at 4oC results and Discussion.

2) The order of the results should be reorganized totally. In my opinion, the results should go in order from the more general to the more specific ones TBARS, Chlorophyll, Carotenoids, proteins, dry mass, sugars, FRAP, DPPH, Anthocyanins, phenolics, ascorbic acid.

3) Discussion is not linking investigated parameters between them. In many cases Discussion is before the Results. Discussion is a little bit superficial and I could find wrong statements in several places.

Other comments:

Please check the figure legends. In all of them it is written p ≤ 5. This is a typing mistake, I think.

Table 1 could be presented as table 2.

Subsections in Results and Discussion are missing.

Which type of microplates resistant to H2SO4 you are using for measuring soluble sugars?

Lanes 244, 343-344, 417, 480, 513 - “showed similar general trend with some exceptions”, “revealed general trend” – Please describe the results properly. Those phrases are inappropriate and do not provide information about the result.

Lane 271 – “Upon harvest, antioxidant content decreases, especially in poor conditions.” – Poor conditions. What does it means? Please, specify.

Lane 274 – “The Phe decline after storage in sunflower microgreens, suggesting that tissue electrolyte leakage could be responsible for damage of cell structure and senescence could induce Phe loss.” – I see general mistake here. How could be the electrolyte leakage responsible for damage? Is absolutely the opposite - electrolyte leakage is the result of membrane damage due to ROS. Correct the sentence properly.

Lane 365-368 – “Finally, D cultivar showed opposite response regarding light quality; PL induced initial increase 3 DAS followed by decrease 14 DAS, and WL provoked significant increase 3 DAS with subsequent decrease 14 DAS.“ – Opposite response? It seems they are the same. The graph is indicating something else.

Lane 428-431 – “Besides for the appearance of microgreens, chlorophyll content is important because of its health benefits while the carotenoids play important role in photooxidative processes, thus protect humans against various types of cancer as well as against degenerative diseases.” - Whether they have both, chlorophylls and carotenoids, health benefits due to the same properties they have? Rewrite the sentence.

Line 433 - Most of vegetables are still photosynthetically active after the storage under light conditions [17] what could induce Chl synthesis even at low temperatures. – Did you mean that photosynthesis is inducing Chl synthesis? Chl synthesis has a high energy cost for the plants, especially if oxidative stress is involved. Could you provide a reference for this statement?

Lane 499-501 – “Microgreen in our investigation protected themselves from damage caused by ROS by increasing antioxidant properties of specific bioactive compounds which in turn decreased DPPH and FRAP radical scavenging activities.” – Again, wrong statement. Plants increase the content of antioxidants in response to oxidative stress, not their properties. DPPH and FRAP reflect the antioxidant capacity of the plants. If additional antioxidants are synthesized during oxidative stress their values increase, not decrease.

Lane 524 – “The increased content of anthocyanins would be efficient enough to neutralize harmful radicals in RR and ChR cultivars.” – This is very optimistic statement, in my opinion. I don’t think that only anthocyanins would alleviate the oxidative stress in plant cells. Remove this sentence.

Author Response

Dear Reviewer,

We are grateful for time and effort of the for reading the manuscript. We have carefully read the comments and suggestions. Considering all the proposed changes, we made corrections of our manuscript and answered on all questions.

Please Find the responses listen in attached Word file. Lines referred in review response match revised Manuscript in word document.

Kind Regards

 

Author Response File: Author Response.docx

Reviewer 2 Report

Dear Authours,

thanks for approaching this hot topic on "plant" nutritional quality related to shelf life. The topic is of high soundness atm and would benefit from some highlightings on the issue of food waste.

The manuscript would benefit from adjustments, more references and it really requires attention on the statistical analysis.

The work would also benefit from a direct correlation /connection between the nutritional quality and shelf life improvements. Introduction section should also clearly describe this relation which has already been reported in literature. 

Results & discussion section should be divided in paragraphs.

Please find all relevant comments and suggestions within the attached pdf file.

 

Kind regards

Comments for author File: Comments.pdf

Author Response

Dear Reviewer,

We are grateful for time and effort of the for reading the manuscript. We have carefully read the comments and suggestions. Considering all the proposed changes, we made corrections of our manuscript and answered on all questions.

Please Find the responses listen in attached Word file. Lines referred in review response match revised Manuscript in word document.

Kind Regards

 

Author Response File: Author Response.docx

Reviewer 3 Report

Interesting work with very well presented valuable results. Results are properly presented, compared and elaborated. Here are few remarks:

Introduction

Lines 41-42: "Among the most commonly consumed families of microgreens are Brassicaceae, Lamiaceae and Fabaceae". This sentence should be modified. There are no "families of microgreens" but microgreens from families Brassicaceae etc.

Lines 42-48 and elsewhere: Polyphenols and phenols are in context of this research synonymous. Authors should use one of that two terms for this class of secondary metabolites.

Line 82: "depending on the variety". Not only on variety but also on plant species. 

Materials and methods

Line 115: Did authors sterilized sand used in this experiment?

Line 127: It is better to use Lipid peroxidation intensity or Intensity of lipid peroxidation.

Subchapter 2.2. Content of total polyphenols and dry mass content should be separated into two subchapters.

Line 147: " modified according to [27] using". Names of authors should be inserted here. 

Authors used the same microplate reader (Tecan, Spark, Männedorf, Switzerland) for all measurement and there is no need to repeat that information with every single methods. 

Line 175: "To determine total protein content". Insert word "soluble".

Lines 184-185: "The extraction was repeated twice and 500 μL of combined supernatants was then added to 2 mL tubes and evaporated until dry in a water bath at 85°C. The reaction mixture consisted of 20 μL of sample, 80 μL of purified water and 200 μL of anthrone dissolved in 95% H2SO4.". How authors obtained 20 μL of sample if they evaporate extracts until dry?

Results and discussion

Line 223: Replace term "storage" into "postharvest".

Table 1. How authors get results -1.294 and -1.570 for monomeric anthocyanins content in Daikon cultivar? If there is no anthocyanins in samples, presented results should 0. Concentration can't go into minus. Same apply for table 2. 

 

Lines 235-255: Authors should elaborate why there is significantly higher content of total soluble phenolics in China rose and Daikon cultivars when PL is implemented, while it is completely opposite for Red radish cultivar. 

 

Author Response

Dear Reviewer,

We are grateful for time and effort of the for reading the manuscript. We have carefully read the comments and suggestions. Considering all the proposed changes, we made corrections of our manuscript and answered on all questions.

Please Find the responses listen in attached Word file. Lines referred in review response match revised Manuscript in word document.

Kind Regards

 

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Manuscript ID: horticulturae-2078102

Title: Antioxidant capacity of radish microgreens after storage: influence of growth light

Authors: Selma Mlinarić, Antonija Piškor, Anja Melnjak, Alma Mikuška, Martina Šrajer Gajdošik and Lidija Begović

 

The authors have complied with some of my recommendations, the manuscript quality is improved but it needs more work to be published. The Results/Discussion section is not rewritten, just the order is different now (much better). Be more concise when discuss the results.

 

Comments:

2.7 and 2.8 – write measurement or determination in the method title

2.9 – Statistics – How n=3 when you have three biological replicates? You mean you don’t have any technical replicates of the experiments performed?

Line 261 – Use Italic for Latin names of plants

Line 272 – You discuss phenolics, but phenolic results are not presented at this time. You can discuss lipid peroxidation results when you discuss phenolics

Line 278 - 280 – “Thus, prolonged storage at low temperature led to changes in structural integrity of membranes due to the lack of antioxidants efficient enough to prevent membrane degradation by ROS” - Speculation, how much antioxidants are enough for prevent membrane damage? Remove the sentence

Line 284 - Figure 1 – Correct legends into the graphs, they remained from the previous version

Line 293 and below – Check your reference numbers – After number 48 is coming 61, 68 and again 48, 49, etc.

Line 341 – Dry mass results are not presented at the time, but they are discussed. Remove them and discuss chlorophylls when you write for dry mass

Line 479 – 482 – The same wrong statement “Therefore, cultivars cvP and cv G grown under B:G:R in our investigation protected themselves from damage caused by ROS by increasing antioxidant properties of specific bioactive compounds which in turn increased DPPH and FRAP radical scavenging activities.” is written here, but now DPPH and FRAP capacities increase instead of decrease. Plants increase the content of antioxidants in response to oxidative stress, not their properties. Property and content are very different. DPPH is a measure for free-radical scavenging properties and FRAP for total antioxidant activity. Not possible to use radical scavenging for both. Why you write “increased DPPH and FRAP radical scavenging activities” when in almost all results presented by you, they decreased? Correct according to results you obtained and not use wrong statements (use increased content instead of property). “protected themselves from damage” – use another phrase, is not very scientific

Line 500 - 510 – 3.5 – Again, Discussion after control results and after DAS results. Please, correct as you corrected the results above

Line 530 –535 “Therefore, low temperature during storage slowed down metabolic processes leading to  deficiency of certain essential factors in metabolic pathways that finally stopped the AA synthesis in radish microgreens in our investigation.” - Speculation, which factors are missing and how you prove this? Reference for this is also missing. You didn’t measure Ascorbate/dehydroascorbate content and enzymes from its biosynthetic pathway to say that synthesis is stopped. Ascorbate could be synthesized and used by the plant. Asc alone or involved in some biochemical cycle is protecting the plant? “degradation of AA occurred to protect themselves from oxidative damage” – the style is not scientific

Line 566, 569, 581 – Ocimum cultivars and Perilla plants should not be in Italic, I think

Line 593 – 605 – Again, Discussion after control results and another Discussion after DAS results. Please, correct as you corrected the results above

Author Response

Dear Reviewer 1,

We are grateful for Your time and effort for reading the manuscript. We have carefully read the comments and we are grateful for constructive suggestions. Suggested corrections of our manuscript were made and Reviewer`s questions were answered. We hope that You will be satisfied with our corrections and hope that our revised manuscript will be recommended for publication in Horticulturae, special issue.

Please, find our responses in attached document.

Kind regards

Author Response File: Author Response.docx