Optimization of fermentation process of Panax quinquefolius and Lycium barbarum sweet fermented glutinous rice by response surface methodology and antioxidant activity

In this study, using Panax quinquefolius, Lycium barbarum and glutinous rice as raw materials, and sweet Jiuqu as saccharification fermentation agent, P. quinquefolius and L. barbarum sweet fermented glutinous rice was prepared. Taking the alcohol content and sensory score as evaluation indexes, the fermentation process were optimized by single factor and response surface tests, and the physicochemical and microbiological indexes, the contents of total phenols and total flavonoids, and the antioxidant activity were analyzed. The results showed that the optimal fermentation process conditions of the wine were as follows: P. quinquefolius extract addition 5.0%, L. barbarum pulp addition 7.6%, sweet Jiuqu addition 1.0%, fermentation time 48 h, and temperature 30 ℃. Under the optimal process conditions, the sensory score of P. quinquefolius and L. barbarum sweet fermented glutinous rice was 94.4 points, the alcohol content was 1.83%vol, the contents of total acid and soluble solid were 4.63 g/L and 22.67%, respectively. It had a special fermentation aroma of sweet fermented glutinous rice, with orange yellow, sweet and sour. The contents of total flavonoids and total phenols of the wine were 127.7 mg/L and 28.1 mg/L, respectively. The half-inhibitory concentration (IC₅₀) values to 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radicals were 0.27 ml/ml and 0.716 ml/ml, respectively, indicating that the product had good antioxidant properties.