Abstract:To develop a Lactobacillus rhamnosus-fermented Polygonati Rhizoma and Cistanches Herba compound oral liquid，sensory score was used as the evaluation index. A single-factor method combined with response surface methodology was employed to optimize the fermentation parameters and to investigate the effects of the volume ratio of Polygonati Rhizoma to Cistanches Herba，inoculum size，and fermentation time on product flavor. Meanwhile，the in vitro antioxidant activity of the fermented oral liquid was assessed by DPPH and ABTS+ free radical scavenging rates. The results showed that the optimal fermentation conditions for the L.rhamnosus-fermented Polygonati Rhizoma and Cistanches Herba compound oral liquid were as follows：a volume ratio of Polygonati Rhizoma to Cistanches Herba of 21∶19，an inoculum size of 8.04×106 CFU/mL，and a fermentation time of 31 h，with a sensory score of 89.1. Under these conditions，the fermented compound oral liquid had a total acid content of 3.85 mL/100 mL，a reducing sugar content of 31.84 mg/mL，a polysaccharide content of 2.97 mg/mL，a flavonoid content of 0.65 mg/mL，and a polyphenol content of 0.80 mg/mL. The DPPH and ABTS+ free radical scavenging rates were 75.0% and 62.7%，respectively，indicating good antioxidant activity.