Changes in Antioxidant Components and Antioxidant Potentials of Soybean During Monascus-Fermentation

Abstract

This study was designed to investigate the changes in antioxidant components and the in vitro antioxidant activities of 80% ethanolic extracts from soybeans fermented with Monascus pilosus 60084. White and black soybeans were incubated during 45 days at 27 ℃ and collected at 5 days intervals of Monascus-fermentation. The concentrations of mevinolin, CoQ10, and tocopherol were analyzed by HPLC. The total phenols, total flavonoids, total carotenoids, and proanthocyanidins were determined by spectrophotometry. The highest contents of mevinolin (568.18 μg/ g dry weight, DW) and CoQ10 (65.59 μg/ g DW) were obtained from Monascus-fermented white soybean after 20 days of fermentation at 27℃. The highest yields of total flavonoids (0.57 mg catechin equivalents, CE/g DW), total phenols (10.49 mg gallic acid equivalents, GAE/g DW) and proanthocyanidins (15.31 mg CE/g DW) were obtained from white soybean at 35 days and 40 days of Monascus-fermentation, respectively. The maximum yield of total tocopherol (312.87 μg/g DW) was produced in unfermented white soybean. The highest production of total carotenoids (25.42 μg β-carotene equivalents, BCE/g DW) was obtained from black soybean at 45 days of fermentation. All fermented soybeans showed antioxidant potential (0.77-3.79 mg Trolox equivalents, TE/g DW), which was measured by radical scavenging activity and the reducing power. A strong correlation (p<0.01) was found between contents total phenolic (r2=0.847), CoQ10 (r2=0.822) and the antioxidant parameters. This suggest that total phenolic and CoQ10 contents are likely significant contributors to the antioxidant capacity of Monascus-fermented soybeans. The results indicate that Monascus-fermentation have great potential for the enrichment of natural antioxidants such as CoQ10 and phenolic compounds in soybeans.