Abstract
Monascus purpureus (M. purpureus) is a species of mold that is traditionally and widely used in China and is vital in the production of fermented foods. Recent studies have shown that its secondary
metabolites exhibit a variety of physiological activities, which suggests that there is potential for this strain to be developed for use in many applications, and it has therefore attracted a great deal of attention in the domestic and overseas functional food industry. In addition to the production of many physiologically-active substances, M. purpureus can also create a natural pigment, and is therefore an important material in food processing.
A M. purpureus strain, CWT715, isolated from the natural environment and confirmed to not produce mycotoxin citrinin was used in this study. After cultivating the M. purpureus strain in a medium containing shiitake stipes or distillers’ grains as the nutritional source, the secondary metabolites produced by the cultures were compared, and the results showed that the antioxidants generated by the M. purpureus cultured with wine lees exhibited a higher antioxidant activity than that cultured with Chinese mushroom stalk. The culture grown in the wine lees medium was therefore used for further investigation of the optimal culture conditions for the production of antioxidants. Our results indicated that the optimal conditions were as follows: the highest chelating ability on ferrous ions of 61.47 ± 0.37% (P<0.05) was observed on the first day of culture, in 75ml culture medium of a 5% concentration; the best reducing ability (Prussian blue) of 3.24 ± 0.02 (P<0.05) was observed on the second day, in 100ml of culture medium of a 5% concentration; and the highest ABTS free-radical scavenging activity of 374.13 ± 0.00% (P<0.05)was noted on the third day of culture, in 75ml culture medium of a 3% concentration. The antioxidant activity was higher in all experiments than the activity of 0.72±0.01 (P＜0.05) shown by Trolox and Vitamin C. Furthermore, in our study, both the proteins
and the total phenolic compounds in the fermentation broth exhibited
antioxidant activity, revealing a potential valuable use for M. purpureus in the development of health food products, which should be further investigated.
