Health-Promoting Properties of Fresh and Processed Purple Cauliflower

Round  1

Reviewer 1 Report

This is an interesting paper. There are only few papers on purple cauliflower and no paper on health-promoting properties of this vegetable. I think that the manuscript could be published in Sustainability. There are several paper which should be mentioned in the Introduction and partially in the Discussion.

Kalisz et al. (2019) performed a Survey of 17 elements, including rare earth elements, in chilled and non-chilled cauliflower cultivars. SCIENTIFIC REPORTS, 9, 5416.

DOI: 10.1038/s41598-019-41946-z

This study investigated if genetic diversity among cauliflower cultivars (white 'Xenia' F-1, green Witaverde' F-1, purple 'Graffiti' F-1, orange 'Sunset' F-1, romanesco 'Cello' F-1) and transplant chilling are reflected in the content of 17 elements in mature curds. Transplants at 40 days after sowing were exposed to 4 degrees C (chilling) and 18 degrees C (control) for 7 days and then planted in the field till harvest maturity. The lowest Ag, Al, Co, and Li contents were found in 'Cello' F-1 cauliflower, which also had the highest Ba and Sr levels. Orange curds of 'Sunset' F-1 were the richest in Al, and high in Li, Sc, and Sn. Chilling applied to the transplants increased Ag, Ba, Co, Sc, Sr, and Tb, and decreased the Y content of mature curds. Transplant chilling can permanently alter plant metabolism, and subsequently may affect the mineral composition of the curds.

Mineral composition of cauliflowers with differently coloured curds modified by the chilling of juvenile plants was investigated by Kalisz et al. (2018). SCIENTIA HORTICULTURAE, 232, 216-225.

DOI: 10.1016/j.scienta.2018.01.010

An experiment involving five cauliflower cultivars that form curds of different colours (white, green, purple, orange, and romanesco) was carried out to determine the effects of genotype and transplant chilling on the content of 18 major and trace elements. Transplants aged 4.5 weeks were treated with 4 degrees C or 18 degrees C temperature for 7 days and then planted in the field. Mature curds were sampled after next 2 months. The use of cauliflowerprovides new opportunities to study nutrient accumulation in the unique edible organ of the plant formed from meristematic tissues depending on genotype and stress applications. White-curded cauliflower Xenia F-1 usually accumulated the least amount of macro- and micronutrients and the lowest content of N, P, S, B, Fe, and Cu. Romanesco Celio F-1 accumulated the lowest content of Na, Pb, Cr, and Ni but also the highest content of Ca, Mg, S, Cu, Mn, and Zn, indicating this cultivar as valuable component of functional food. Low temperature increased the content of N, P, Ca, S, Mg, Na, B, Cu, Zn, and Pb but decreased the content of Mo and Cr in the curds of certain cultivars. The results demonstrate alterations in plant metabolic pathways due to low temperature applied at the juvenile stage persist through harvest, which proves the existence of stress memory.

Volden et al. (2009) investigated processing (blanching, boiling, steaming) effects on the content of glucosinolates and antioxidant-related parameters in cauliflower (Brassica oleracea L. ssp botrytis). LWT-FOOD SCIENCE AND TECHNOLOGY, 42(1), 63-73.

DOI: 10.1016/j.lwt.2008.05.018

Five different varieties of cauliflower (Brassica oleracea L. ssp. botrytis); two white (cv. 'Aviso', 'Dania'), one purple (cv. 'Grafitti'), one green (cv. 'Emeraude') and one romanesco/green pyramidal (cv. 'Celio') cultivar have been studied. All samples were thermally processed and the effects on the levels of glucosinolates (GLS), total phenols (TP), total monomeric anthocyanins (TMA), L-ascorbic acid (L-AA) and antioxidant capacities (FRAP and ORAC) were investigated. Processing methods applied were: blanching (3 min), boiling (10 min) and steaming (10 min). Total GLS were significantly (p < 0.05) affected by processing with the highest losses, 55 and 42% on average, occurring for boiled and blanched samples, respectively. Significant effects were also noted for steaming, but to a lesser extent, i.e. 19% average reduction. Antioxidant-related parameters were similarly affected with average losses of 27, 33, 36 and 46% in boiled cauliflower and 16, 21, 22 and 28% in blanched for TP, FRAP, L-AA and ORAC, respectively. Blanching and boiling reduced TMA in purple cauliflower by 38 and 53%, respectively. Steaming affected the antioxidant-related parameters the least for all cultivars. L-AA was significantly reduced by 14% in all cultivars by steaming. Some differences in behaviour between cultivars were noted, especially between white and coloured cultivars for TP, FRAP and L-AA, but also for some GLS. The main losses were caused by leaching into the processing water. 

Author Response

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Reviewer 2 Report

The aim of the paper “Health-promoting properties of fresh and processed purple cauliflower” seem to be an investigation about the effects of some cooking methods and frozen storage of a purple cauliflower genotype on some nutritive and non-nutritive compounds.

Cauliflower contains several healthy compounds and a lot of studies have been carried out as regards its characterization also after different cooking methods and storage conditions. In this context, the literature documents a significant influence of the post-harvest treatments on cauliflower nutritional quality.

In my opinion this manuscript don’t reports results which can be encompassed in food and agriculture engineering (aims of the Special Issue “Sustainable Production in Food and Agriculture Engineering”). Moreover, the significance of the results of the present manuscript for the readers of the “Sustainability” journal seem to be very low, considering aim and scope relating to “cultural, economic and social sustainability of human beings”. I suggest of submitting this manuscript to other MDPI journals such as “Foods”.

Author Response

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Reviewer 3 Report

The topic of the article is current, therefore it can get interest from the potential readers of scientific journals. An open question that this topic much more fit into a food safety journal, so Editors have to decide if it is meets the scope of this one. The English of paper seems perfect and the ratios of different chapters are also suitable. The introduction gives a strong base to prove the significance of experiment, but contains only a few references – but they are in the discussion section, where a lot of previous papers are used to explain the findings. The Materials section have to be improved (see later). The statistical methods are suitable. The Result chapter presents thoroughly the given results. In Discussion authors compared their results to literary data and emphasizes the similarities and differences and due to the detailed explanations, comparisons to other previously published papers and presentation of possible explanations it is a very valuable part of the manuscript.

My comments are:

- In the Materials and methods section there are very short introduction about the parameters of cultivation (Line82-) – environmental parameters, agronomy, time (maturing stage) and method of harvest. Too few information about the blanching and cooking (L88-)- it was 4 minute, but how the oven was filled? Temperature, relative humidity values? L96- The conventional cooking was 15 mins, but from the placing in or from the re-boiling after placing in? After cooking and blanching the samples were cooled naturally or by chiller or they were packed hot? What was the time between the preparation and analysis of non stored samples (L93-95)?

- The description of analytical methods is adequate, but in L134 please, place a space between the number and unit (105 °C).

- In Discussion section authors wrote that “the final chemical composition of the examined vegetable also affects significantly the cultivar.” (L280), altough they do not present results of other cultivars. In L313 use „respiration” instead of „breathing”.

The paper is not only interesting but a result of a thorough evaluation with valuable literary summary and comparison, therefore it can be recommend for publication. But the application of treatments have to be describe more detailed.

Author Response

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Reviewer 4 Report

The subject of article falls within the scope of the journal Sustainability in the area of food sustainability. Manuscript is readable and good organized. Study is well executed. Authors had used known methods for the determination of selected components content in purple cauliflower after various methods of treatment. The part Discussion is well prepared and authors’ results are compared with many other researchers.  

The manuscript should exactly follow the Instructions for Authors. It contains a lot of formal errors (highlighted in the text).

I strongly suggest using the term “mass” instead of “weight” in paper, lines 120, 126, 139, 158, 165, 230, 260, 267, 391.

In scientific papers, it is unusual to use for time intervals terms as “4-minute” or “20-minute”, respectively (lines 88, 89).

SI units have to be used in manuscript, but in line 101 is unit “bar”. Also, the internationally agreed abbreviations of SI unit have to be used in text and in the tables, e.g. line 96 – instead of “15 minutes” right will be “15 min”; line 139 – instead of “100 gram” right will be “100 g”; Tables 1 and 2 – instead of “μm Trolox/g d.m.” right will be “μmol Trolox/g d.m.”; line 264 – unit is missing”; lines 357, 359 – instead of “25.7 μM Trolox equivalent per 1 g” right will be “25.7 μmol Trolox equivalent per 1 g”.

Parentheses should be adjusted or supplemented in lines 73, 122, 247.

Free spaces should be around the character ≤, e.g. lines185, 187, 190, 204, and also on other lines.

Between value and physical unit has to be a free space – lines 91, 93, 102, 134, 152, 283, e.g. instead of “-22°C” right will be “-22 °C”.

In Table 1, such bold lines should not be used. In Table 2, the decimal point should be in numbers instead of comma. Line 203 – the value “1336.36 mg/100 g” is different as in Table 2, it should be corrected.

Citations and References should also exactly follow the Instructions for Authors. Lines 274, 275 – the sentence “According to the literature, dry matter content in the fresh white rose of Romanesco cauliflowers ranges from 6.96 to 13.95 g/100 g, which agrees with our results [31,32].” will have a more correct meaning if the citations are immediately after the word literature, it means “According to the literature [31,32], …”. Lines 321, 322 – citation “Volden et al. [38]” is there 2 times. Line 336 – the name of author is written as “Puupponen-Pimia”, but in References “Puupponen-Pimiä”, it should be corrected. In References, the names of the authors should be separated by a semicolon, not by a comma. If the authors use the website in References, other information has to be also added: Available online: URL (archived on Day Month Year) – e.g. lines 459, 460. Line 486 – word “avaluation” has to be corrected.

Comments for author File: Comments.pdf

Author Response

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Round  2

Reviewer 2 Report

I've not seen flaws in the methodology and the data are properly presented and interpreted. I consider the manuscript suitable for pubblication.