Effect of Culinary Treatment on Changes in the Contents of Selected Nutrients and Non-Nutrients in Curly Kale (Brassica oleraceaVar.acephala)

Abstract

Kale has a great nutritive value, very high antioxidant activity and pro-healthy potential. The level of phytochemicals and related bioactive compounds are strongly dependent on pre and postharvest stages of production chain (domestic or industrial). The study investigated changes in the levels of vitamin C, β-carotene, total polyphenols, antioxidant activity, degradation products of glucosinolates as well as nitrates and nitrites in the kale due to the conventional cooking process. As a result of cooking kale, a significant decrease was noted in the content of vitamin C, polyphenols, diindolilometan, indole-3-acetic acid and nitrate and nitrites, and a significant growth in the content of β-carotene, indole-3-carbinol, indole-3-acetonitrile, total indoles and total isothiocyanate compared with the raw vegetable. It has been found that kale, fresh and cooked, had similar antioxidative potential. Practical Applications Brassica species are commonly occurring in a diet as an additive to meat dishes and other rich-in-fat products, which favor tumor transformation. Due to their high consumption and availability over the whole year, brassicas may potentially be a crucial element in chemoprevention of cancer. The weakness of vegetables is their seasonal availability and fact that they are perishable. During processing of these vegetables for food preparation the most commonly used technique is cooking. Food technology is focused on discovering and establishing the methods of food processing, which will least affect their chemical composition. It is very important to know how to optimize, e.g., conventional cooking process to preserve beneficial and bioactive compounds of vegetables.