Antioxidant and antiproliferative activities of different varieties of cauliflower (Brassica oleracea var. botrytis) after cooking processes.

Cauliflowers are well-known for their health benefits and they are becoming increasingly popular as a fresh vegetable significant source of nutritional antioxidants, such as vitamins and carotenoids, or biologically active dietary components, such as the polyphenols and glucosinolates [1]. Cauliflowers are also a rich source of nutrients such as calcium, zeaxanthin and lutein which have a protective action in eye health and they can also help in the prevention of cancer through the flavonoids known as quercetin or phytonutrient as sulforaphane [2]. Cultivation of coloured cauliflowers (Brassica oleracea var. botrytis) is spreading in Italy and this is also a consequence of the significant genetic improvement on the white type “Tardivo di Fano”, the green types “Verde di Macerata” and the violet type “Violetto di Catania” [3]. Recently, in the framework of a genetic improvement programme, pure lines of “orange type” were obtained [4]. Cooking as a domestic processing method has a great impact on food nutrients. Most vegetables are mainly consumed after being cooked, and cooking considerably affects their health-promoting compounds (glucosinolates, phenolic compounds, phytochemicals, and vitamin C). The cooking process is more important also to determine the quality and recovery of biological active components that characterized the different variety of cauliflowers selected. The aim of this work was to study the influence of these conditions during boiling water and microwave cooking on some properties of coloured cauliflowers. Total polyphenols, antioxidant activity, and antiproliferative activity on human breast adenocarcinoma cell line MDA-MB 231 were evaluated after cooking processes. The results showed that the antioxidant activity, tested using ABTS assay, was reduced during the cooking in all cauliflower varieties. An increase of antioxidant activity in orange and violet varieties was observed when tested with DPPH and FRAP assays. Furthermore, the phenolic substances increase in methanol extracts after cooking processes, especially with microwave treatment. The antiproliferative activity on MDA-MB 231 tumour cell line shows an increase in orange and violet cauliflower aqueous extracts cooked with microwave. In conclusion, the change of properties results lower for orange and violet cauliflowers respect to white or green varieties after cooking processes. In some case the cooking processes increase the antioxidant and antiproliferative activity. The best cooking method that preserves the healthy properties of all varieties of cauliflower is the microwave treatment. [1] Raiola A, Errico A, Petruk G, Monti DM, Barone A, Rigano MM. Bioactive Compounds In Brassicaceae Vegetables With A Role In The Prevention Of Chronic Diseases. Molecules. 2017;23(1), pii: E15. [2] Rosa EAS, Heaney RK, Fenwick GR, Portas CAM. Glucosinolates in Crop Plants, in Horticultural Reviews, Volume 19 (ed J. Janick), 2010, John Wiley & Sons, Inc., Oxford, UK. [3] Acciarri N, Sabatini E, Rotino GL, Ciriaci T, Pulcini L, Della Campa M, Maestrelli A. Breeding In Progress In New Typologies Of Orange Cauliflowers (Brassica oleracea var. botrytis) Proceedings of 5th International Symposium on Brassicas and the 16th Crucifer genetic Workshop. Lillehammer, Norway. 8-12 September 2008. [4] Lu S,Van Eck J, Zhou X, Lopez AB, O’Halloran DM, Cosman KM, Conlin BJ, Paolillo DJ, Garvin DF, Vrebalov J, Kochian, LV, Kupper H, Earle ED, Cao J, Lia L. The Cauliflower Or Gene Encodes A Dnaj Cysteine-Rich Domain-Containing Protein That Mediates High Levels Of β-Carotene Accumulation. Plant Cell 2006;18:3594-3605.