Antioxidant activity of the extracts from freshwater macroalgae (Cladophora glomerata) grown in Northern Thailand and its preventive effect against lipid oxidation of refrigerated eastern little tuna slice

Abstract

© 2019, Central Fisheries Research Inst. All rights reserved. Characteristic and antioxidant activity of the extracts from freshwater macroalgae (C. glomerata) as influenced by extraction media, i.e., water or ethanol (20-100%, v/v) were studied. The highest yield (28.0%) was obtained when water was used. Ethanolic extracts had significantly lower yields (2.98-15.5%) (P<0.05). However, total phenolic and chlorophyll contents were lower in water extract. Among all extracts, the 60% ethanolic extract (E60) had the highest antioxidant activities, including DPPH and ABTS radical scavenging activities, ferric reducing antioxidant power and metal chelating activity. Based on LC/MS of E60, quercetin, isoquercetin and hydroquinin were the major phenolic compounds. When E60 at different levels (100, 200 and 400 mg/kg) were added to eastern little tuna (Euthynnus affinis) slices, the reduction in lipid oxidation was dose-dependent (P<0.05) as shown by smaller increases in peroxide and thiobarbituric acid-reactive substances (TBARS) values, compared to the control. Therefore, C. glomerata could be a source of alternative natural antioxidant in lipid based muscle food.