Optimization of Fermentation Conditions and Antioxidant Activity of Agaricus bisporus Stipe Enzyme

In this paper, Agaricus bisporus stipe was used as the raw material, Lactobacillus plantarum inoculation amount, sugar addition amount and fermentation time were the main factors, and the total phenol content was used as the evaluation index. Based on single factor experiments, the Agaricus bisporus stipe enzyme was optimized by response surface experiments. Fermentation process, and the antioxidant capacity of the enzyme products before and after fermentation and storage at 4 ℃ and 25 ℃ for 5 d were studied. The results showed that the optimal process conditions for fermentation of Agaricus bisporus stipe enzyme were: Lactobacillus plantarum inoculation amount was 3%, 9.50% of sugar added, and fermentation time was 24 h. The total phenol content of the enzyme product could reach 2.20 mg/mL, which was equal to the predicted value of 2.19 mg/mL. The study found that the contents of total phenol and ascorbic acid in the Agaricus bisporus stipe enzyme were 2.20 mg/mL and 44.40 µg/mL, respectively. The DPPH free radical scavenging capacity, ABTS free radical scavenging capacity, ferric ion reducing antioxidant power and total antioxidant capacity were 51.93%, 52.11%, 0.70, 28.09 U/mL, respectively, which were significantly higher than those before fermentation. Further analysis of the antioxidant activity of the enzymes under the storage conditions of 4 ℃ and 25 ℃ showed that the enzymes stored at 4 ℃ had stronger DPPH, ABTS radical scavenging ability, iron ion reducing ability and antioxidant ability at 0 d storage. After 1 d storage, the antioxidant capacity of the enzyme began to decline sharply, and the antioxidant capacity of the enzyme stored at 25 °C was significantly lower than that stored at 4 °C (P<0.05).