Phenolics, ascorbic acid, carotenoids and antioxidant activity of broccoli and their changes during conventional and microwave cooking

Antioxidant components, including phenolics, ascorbic acid and carotenoids, of broccoli floret and stem, antioxidant activity, and their changes during conventional and microwave cooking, were investigated. Broccoli florets and stem were cooked by conventional boiling or by microwave over up to 300 s. Total phenolics were retained by up to 28.1-28.4% in the cooked florets and 55.6-57.8% in the cooked stems, and ascorbic acid by 34.1-34.4% and 29.1-29.5%, respectively. Total carotenoids were retained better compared to total phenolics and ascorbic acid. Total antioxidant activity was retained at 34.7-35.0% in the cooked florets and 34.6-34.7% in the cooked stems and phenolic antioxidant activity was retained at 37.4% and 64.7%, respectively. The results showed that antioxidant components and antioxidant activity in broccoli were lost heavily during the cooking. These losses need to be taken into account when calculating the dietary intake of these compounds from the cooked broccoli. (C) 2004 Elsevier Ltd. All rights reserved.