Effects of C/N Ratio on the Changes of Active Substances and Antioxidant Capacity of Fungus Fermented Mulberry-Oat Bran

Ganoderma lucidum, Hericium erinaceus, Phellinus igniarius and Oudemasiella radiate were used to prepare medicinal fungal matrix through bi-directional solid fermentation in the medium of mulberry and oat bran under the four different C/N ratios. Then, the growth status of different fungi, the contents of main active substances and the antioxidant activity of the water and ethanol extract of fungal matrix were studied. Results showed that:With the increasing of C/N ratio, there was no significant change in the mycelial growth rate of Ganoderma lucidum and Oudemasiella radiate, and that of Hericium erinaceus and Phellinus igniarius increased significantly (p<0.05). The contents of active constituents of mixed fungi changed obviously. When the ratio of C/N was 20:1 (g/g), the polysaccharides of Phellinus igniarius and Oudemasiella radiate reached (132.8±1.16) and (111.22±4.83) mg/g dry matter. The polypeptide increased obviously of Phellinus igniarius and Oudemasiella radiate increased more than doubled. The flavonoids also increased obviously, but the total polyphenols decreased. When the ratio of C/N was 50:1 (g/g), the total polyphenols of Hericium erinaceus, Phellinus igniarius and Oudemasiella radiate were decreased (6.57±0.18), (6.78±0.25) and (5.64±0.47) mg/g dry matter, a decrease of about 1/3.In addition, the ethanol extract of fermented products had strong scavenging ability on DPPH free radicals, and the highest scavenging rate of Ganoderma lucidum reached 96.90% at 40:1 (g/g) C/N ratio. Four kinds of fungi for the removal ability of hydroxyl radicals also had much more obvious improvement. It aimed to explore more edible and medicinal fungi to apply for food, health products and cosmetics in the future.