The comparison of antioxidant activities between non-boiled and boiled aqueous extracts of selected vegetables from the Brassica oleracea L. species is an interesting study topic, particularly in a context like Sri Lanka, where traditional and modern medicinal practices often emphasize the role of dietary plants in health. Hence, this was aimed to evaluate the antioxidant potential of boiled and non-boiled aqueous extracts (BAE and NBAE respectively) of selected vegetables belonging to the Brassica oleracea L species, which are commonly consumed as a raw vegetable in fresh salads as well as a cooked vegetable in curry or fried form i.e. Brassica oleracea L. var. italica (Broccoli), Brassica oleracea L. var. capitate (White Cabbage), Brassica oleracea L. var. gongylodes (Kohlrabi), Brassica oleracea L. var. botrytis (Cauliflower). The antioxidant activity of boiled and non-boiled aqueous extract of each vegetable was evaluated by using a 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay where Ascorbic acid was a positive control. All results were analysed by SPSS statistic software version 21 and p < 0.05 was considered as statistically significant. The results showed that BAE of white cabbage, kohlrabi and cauliflower showed significant (p < 0.05) enhancement in antioxidant activity compared to their NBAE. There is the absence of a significant difference between NBAE and BAE extract of Brassica oleracea L. var. italica (Broccoli). However, broccoli showed the highest antioxidant potential compared to other tested Brassica vegetables. These findings could provide valuable insights for nutritionists, food scientists, and health-conscious consumers in selecting the best Brassica family vegetable for optimizing the antioxidant intake from these commonly consumed vegetables and also recommending food preparation methods.
Dassanayake et al. (Mon,) studied this question.