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Y. F. NG and P. C. K. Cheung. Food and Nutritional Sciences Programme, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China Dietary antioxidants have been studied intensively for their prevention of coronary heart diseases (CHD) of which inhibition of the oxidation of LDL cholesterol is a major mechanism. Our previous studies have shown that edible mushrooms are rich in phenolic antioxidants that have strong radical scavenging effect to inhibit lipid peroxidation. Moreover, thermal dehydration would induce the formation of Maillard reaction products with antioxidative properties in food and dried mushroom was found to contain higher phenolic content and exhibits stronger antioxidant activity than fresh one. This project compared the in vitro antioxidant activity of extracts obtained from the fresh and oven-dried samples of an edible mushroom, Agrocybe aegerita (Aa) in terms of inhibition of lipid peroxidation and their total phenolic content. Ethanolic and water crude extracts obtained from fresh and oven-dried Aa were evaluated for their antioxidant activity by a modification of the beta-carotene bleaching method and their total phenolic content measured by the Folin-Ciocalteu method was expressed as gallic acid equivalent (GAE). Fresh and oven-dried Aa exhibited moderate to strong antioxidant activity (ranged from 41.3%-63.1% for the ethanolic extract and 22.9%-35.1% for the water extract). The phenolic content in the ethanolic and water extracts from dried Aa were 76 GAE and 15 GAE, respectively, while for that of the fresh Aa were 70 GAE and 10 GAE, respectively. In general, dose-dependent relationship was found in the extracts of the two Aa samples and the ethanolic extract had higher antioxidant activity and more phenolic content than the water extract. Aa contains phenolic antioxidants of which inhibition of lipid peroxidation could be enhanced by oven-drying. Extracts from Aa can be further investigated for their potential to be developed as dietary antioxidant.
Session 29, Food Chemistry: Antioxidants and bioactive agents
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