Abstract: To investigate the effect of lactic acid bacterial fermentation on the release and functional activities of active substances in ginseng during in vitro simulated digestion, this study established an in vitro oral-gastric-intestinal digestion model. High performance liquid chromatography (HPLC) was used to analyze the dynamic changes in total phenols, total flavonoids, polysaccharides, and monomeric ginsenosides during the digestion of ginseng fermented and not fermented with Lactiplantibacillus plantarum. Additionally, the antioxidant activity and hypoglycemic activity of the resulting digests were evaluated. The results indicated that lactic acid bacterial fermentation significantly promoted the release of active substances during in vitro simulated digestion. In the intestinal digestion stage, the release of total phenols from fermented ginseng reached (3.65 ± 0.11) mg/g, which increased 30.3% compared with non-fermented ginseng (P < 0.05). The release of total flavonoids from fermented group temporarily decreased during the gastric digestion stage, due to the acidic environment, but increased to (1.18 ± 0.04) mg/g in the subsequent intestinal digestion. Furthermore, compared with the non-fermented control, fermentation significantly increased the release of the rare ginsenosides F2, Rg3, CK, and Rh2 from (10.21 ± 0.19), (0.62 ± 0.13), (1.43 ± 0.16), and (0.38 ± 0.07) mg/g to (12.57 ± 0.07), (8.32 ± 0.54), (7.25 ± 0.21), and (1.81 ± 0.12) mg/g during the intestinal digestion stage, respectively. After intestinal digestion, the 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical cation scavenging capacity, ferric ion reducing antioxidant power (FRAP), superoxide anion radical scavenging capacity, and α-glucosidase inhibitory activity of fermented ginseng were (89.22 ± 3.04)%, 0.57 ± 0.01, (41.36 ± 0.96)%, and (83.81 ± 0.71)%, respectively, which were 21.8%, 15.2%, 141.3%, and 8.3% higher than those of the non-fermented control, respectively. Correlation analysis revealed that the contents of total phenols, polysaccharides, and rare ginsenosides (F2, Rg3 and CK) were positively correlated with antioxidant and hypoglycemic activities, while the prototype ginsenosides Rg1 and Re were negatively correlated with both activities. In conclusion, lactic acid bacterial fermentation transforms prototype ginsenosides in ginseng through enzymatic hydrolysis, synergizing with the digestive environment to further promote the release and transformation of active substances, significantly enhancing the bioavailability and functional activity of digestive products. This study provides a theoretical basis for developing high-value-added functional foods based on ginseng.

Key words: lactic acid bacterial fermentation; ginseng; in vitro simulated digestion; rare ginsenosides; antioxidant activity; α-glucosidase inhibitory activity