Abstract:

In this study, coix seeds were subjected to fermentation by Aspergillus niger, Aspergillus oryzae and Monascus, respectively. The contents of polypeptides, total sugar and polyphenols were determined to evaluate the change of compositions in coix seeds during the fermentation process. Meanwhile, the scavenging rate of hydrolysates to DPPH free radicals was also determined to evaluate its anti-oxidant activity. Results showed that polypeptide content, total phenols content, degree of hydrolysis and scavenging rate to DPPH free radicals exhibited a gradient increase during the fermentation process. Polypeptide content, total phenols content, degree of hydrolysis and scavenging rate of DPPH free radicals were 6.14 mg/ml, 0.10 mg/ml, 24.9% and 10.2% during Aspergillus niger fermentation; 2.58 mg/ml, 0.089 mg/ml, 31.1% and 10.4% during Aspergillus oryzae fermentation; and 2.93 mg/ml, 0.086 mg/ml, 14.7% and 18.9% during Monascus fermentation. In addition, the content of total sugar exhibited an increase up to 84.0 mg/ml and 76.1 mg/ml, respectively, during Aspergillus niger and Aspergillus oryzae fermentation; whereas the content of total sugar was observed a significant decrease to 8.5 mg/ml during Monascus fermentation.

Key words: coix seed, Aspergillus niger, Aspergillus oryzae, Monascus, polypeptide content, total sugar content, DPPH free radical