Carrots (Daucus carota L.) Biofortified with Iodine and Selenium as a Raw Material for the Production of Juice with Additional Nutritional Functions

Round 1

Reviewer 1 Report

A significant  increase in I and Se content was observed for juices from treated carrots. Carrot biofertilization with iodine and selenium is connected with decreased content of dry matter, total  soluble solids, protein, sugars and β-carotene in the juices, and lower antioxidative activity compared to the control. The increased content of iodine and selenium largely cover the daily need for these elements.

Research questions are well defined and within the aims and the scope of the journal. Methods are suitable and mainly correctly described. The investigation is performed to good technical standards. It is no ethical problem involved. Conclusions are based on the results. Discussion is  relevant.

Suggestions:

Possibility of daily overdosage of Se and/or I in the case of overconsumption of the juice should be disscused, in relation to the daily demand for these elements.

Lines 95-100. More details are here needed including type of soil, year of experiment, location,  sowing time and sampling time.  Was any fertilisation (selenium or iodine, or other) performed here in the previous year? Which crop was grown in the location in the previous year?

Lines 119-121, more details are needed about the principle of the methods used. By these methods the content was not »determinated«, but only »estimated«.

Author Response

Thank you for reviewing our article and for all critical comments. We are grateful for that. They allowed us to significantly improve the quality of the publication. Our answers are presented below.

Point 1: Possibility of daily overdosage of Se and/or I in the case of overconsumption of the juice should be disscused, in relation to the daily demand for these elements.

Response 1: We thank the reviewer for this remark. We have added a relevant comment regarding the possibility of an overdose of iodine and / or selenium in the article (line 232-238)

Point 2: Lines 95-100. More details are here needed including type of soil, year of experiment, location,  sowing time and sampling time.  Was any fertilisation (selenium or iodine, or other) performed here in the previous year? Which crop was grown in the location in the previous year?

Response 2: We agree with the reviewer that the above-mentioned parameters are important in the conduct of the field experiment and affect the obtained test results. The article was supplemented with basic information (line 112 – 117), while all the details concerning the physicochemical properties of the soil (e.g. pH, EC, Eh, soil texture class, etc.), the cultivation details (fertilization, amount of seeds etc.) of the experiment and weather conditions were described in our earlier work. (Food Chem. 2019, 300. https://doi.org/10.1016/j.foodchem.2019.125202)

Point 3: Lines 119-121, more details are needed about the principle of the methods used. By these methods the content was not »determinated«, but only »estimated«.

Response 3: We agree with the suggestion that in such describe method it is only possible to estimate the content of TSS. We added to the description taking into account the temperature compensation (used in the experiment), which allows for a more precise determination of the TSS value (line 135-136).

We kindly ask you to acknowledge our arguments and accept the publication in its current form

Author Response File: Author Response.docx

Reviewer 2 Report

General remarks

The current study determined the iodine and Selenium contents of juices from four carrot cultivars biofortified with iodine through soil fertilization  as well as the loss in these elements after thermal processing. The study also compares the  contents of other physicochemical parameters in juices from biofortified and non-biofortified carrot cultivars.

Compared to existing studies that have determined the contents of iodine and Selenium in foods after soil or foliar biofortification, this study goes an extra mile to determine the loss in these elements during heat processing. I believe that this is a key strength of the article, in addition to determining other physicochemical parameters of the processed biofortified foods. I believe the paper is well written and good enough to be published with minimal revision.

Having said this, the authors could consider the following specific comments to further improve the quality of the manuscript.  

Specific comments:

1. The title doesn’t look convincing, as the authors do not introduce/define the key aspects of the title in the introduction. For instance, they do not define what “specifically foods production” is or “specifically foods” which is also stated as a key word but never appearing in the main text of the paper. I recommend that the title be revised to reflect the work done.
2. Check the sentence starting in line 28, with “Despite reduction……..” It does not read well.
3. While the paper addresses major research gaps in Iodine and selenium biofotification of food crops, I find that the authors have not given enough justification for the study. In lines 65-78, the authors provide the gaps but do not elaborately state the justification. For instance, why is it important that you look at the loss of these nutrients during processing? Would you do the same for any other nutrient? You have not talked about iodine being a volatile element that can be lost during thermal processing!
4. Mention at least the most common manifestations of iodine deficiency such as goiter and cretinism in the third paragraph of the introduction. I believe that this can motivate first time readers of your article. For selenium, you elaborately mentioned its functions and one can derive the consequence of its deficiency.
5. What was the basis for selecting the I and Se doses for biofortification and why did the authors use only 1 dosage per element?
6. Figure one (scheme of production of carrot juice), a number of spelling errors are seen e.g. under juicing, did you mean Basket press instead of bascet? Sterilization instead of sterylization?
7. It is not entirely clear how the authors calculated the contribution of biofortified juices to the daily intake of I and Se. Considering that I was estimated as mg/kg, how did you calculate the daily intake of iodine from the juice and what was the value?

The authors only stated that the biofortified juice contributed higher doses of iodine and selenium than the non-biofortified. It would be good to state the exact amount of iodine that one would get from consuming 100g of the biofortified juices before expressing the contribution to RDA as a percentage. This would become clearer. The same applies to Selenium.

8. Check the spelling of biofortification in Table 4
9. Conclusion. The authors used carrot fortification. As this is different from biofortification, it would be good to consistently use biofortification (which is what they studied) and not fortification
10. There is need to be consistent with what is stated in the conclusion and the abstract. E.g. in the abstract, the authors stated that biofortification had little effect on color and pH of the juices and in the conclusion, it is written that biofortification affected the color of the juices.

Author Response

Thank you for reviewing our article and for all critical comments. We are grateful for that. They allowed us to significantly improve the quality of the publication. Our answers are presented below.

Point 1: The title doesn’t look convincing, as the authors do not introduce/define the key aspects of the title in the introduction. For instance, they do not define what “specifically foods production” is or “specifically foods” which is also stated as a key word but never appearing in the main text of the paper. I recommend that the title be revised to reflect the work done.

Response 1:

Thanks to the reviewer's suggestion, we decided to change the title to more accurately reflect the work done. Also some of the statements in the introduction have been made more precise to refer to the changed title of the article. In addition there is emphasize an additional function that can be fulfilled by products, including juices, obtained from biofortified raw materials.

The change of the title also affected the modification of keywords (removing specifically food)

Point 2: Check the sentence starting in line 28, with “Despite reduction……..” It does not read well.

Response 2: According to the reviewer's suggestion, the sentence style has been changed

Point 3: While the paper addresses major research gaps in Iodine and selenium biofotification of food crops, I find that the authors have not given enough justification for the study. In lines 65-78, the authors provide the gaps but do not elaborately state the justification. For instance, why is it important that you look at the loss of these nutrients during processing? Would you do the same for any other nutrient? You have not talked about iodine being a volatile element that can be lost during thermal processing!

Response 3: In response to the reviewer's remark, we supplemented the relevant paragraph with a more precise justification of undertaken research (line 85-89).

Determining the losses during the technological process is the most important for the elements in which the raw material has been enriched and constitute an additional nutritional value of the product. Many basic physicochemical parameters (such as sugar content, color, dry matter etc.) of good quality juices, including carrots, are specified. The raw material requirements for obtaining the highest quality products are also known. Therefore, it is not necessary to determine direct changes of these parameters in the technological process, but only whether the use of biofortified raw material significantly affects these parameters. In the case of iodine and selenium, without knowing the losses in the technological process, we cannot state whether the raw material will be of appropriate quality to obtain a product with a specific (desired) content of these elements.

We agree that iodine is a volatile element. However, this problem mainly concerns its mineral connections. In the biofortification process, iodine in the plant is incorporated into organic compounds (mainly iodine derivatives of salicylic acid), most of which will not be volatile or thermolabile compounds. From our as yet unpublished research results it can be concluded that iodine losses are rather related to the dissolution of its compounds in the water environment.

Point 4: Mention at least the most common manifestations of iodine deficiency such as goiter and cretinism in the third paragraph of the introduction. I believe that this can motivate first time readers of your article. For selenium, you elaborately mentioned its functions and one can derive the consequence of its deficiency.

Response 4: We thank the reviewer for valuable opinion. The paragraph on iodine has been expanded to include information about its function in the body and the effects of its deficiency (line 52-56).

Point 5:What was the basis for selecting the I and Se doses for biofortification and why did the authors use only 1 dosage per element?

Response 5: Our team has been conducting experiments related to the biofortification of various vegetables (including carrot, lettuce, spinach, tomato) into iodine and / or selenium since 2009 (https://www.repo.ur.krakow.pl/resultList.seam?q) = & r = publication & t = simple & lang = pl & cid = 8582). The results obtained in previous studies indicated that the dose of 1 kg Se / ha causes too much accumulation of this element (in relation to iodine) in carrot roots, despite the lack of toxicity of the dose applied to the plant.

Described field experiment was a varietal experiment aimed at determining the differentiation of the uptake of the elements used by various carrot cultivars. Additionally, due to the results obtained in previous experiments, the dose was four times lower (0.25 kg / ha). Currently, research is underway to assess the effectiveness of using even lower doses of selenium in the biofortification process.

In the case of iodine biofortification of carrots, we found its effectiveness sufficient in previous experiments, so we did not introduce any further changes.

Point 6: Figure one (scheme of production of carrot juice), a number of spelling errors are seen e.g. under juicing, did you mean Basket press instead of bascet? Sterilization instead of sterylization?

Response 6: Thank you for pointing out the spelling errors that have appeared on the scheme of production of carrot juice. We hope all errors have been corrected.

Point 7: It is not entirely clear how the authors calculated the contribution of biofortified juices to the daily intake of I and Se. Considering that I was estimated as mg/kg, how did you calculate the daily intake of iodine from the juice and what was the value?

The authors only stated that the biofortified juice contributed higher doses of iodine and selenium than the non-biofortified. It would be good to state the exact amount of iodine that one would get from consuming 100g of the biofortified juices before expressing the contribution to RDA as a percentage. This would become clearer. The same applies to Selenium.

Response 7: We thank the reviewer for the valuable comment. The iodine and selenium content in the juice is expressed, as usual for minerals, in mg / kg dry weight. For this reason, when calculating the iodine content in 100 g of fresh juice weight, the data of the dry weight content presented in Figure 3a were used. Then the RDA (for I 150 µg / day and for selenium 55 µg / day) coverage was calculated with the consumption of 100 g of juice. In accordance with the reviewer's requests, the text was supplemented with appropriate values (line 218-221, 230-232).

Point 8: Check the spelling of biofortification in Table 4

Response 8: Spelling error was corrected.

Point 9: Conclusion. The authors used carrot fortification. As this is different from biofortification, it would be good to consistently use biofortification (which is what they studied) and not fortification

Response 9: We agree with the reviewer that fortification means a different process to the biofortification that took place in our experiment. For this reason, the word "fortification" has been replaced in the text by the word "biofortification."

Point 10: There is need to be consistent with what is stated in the conclusion and the abstract. E.g. in the abstract, the authors stated that biofortification had little effect on color and pH of the juices and in the conclusion, it is written that biofortification affected the color of the juices.

Response 10: We agree with the reviewer's opinion. The applied corrections have been introduced in the text.

We kindly ask you to acknowledge our arguments and accept the publication in its current form

Author Response File: Author Response.docx