Effect of in vitro digestion on the total polyphenol and flavonoid, antioxidant activity and carbohydrate hydrolyzing enzymes inhibitory potential of selected functional plant‐based foods

This study aimed to investigate the effect of in vitro digestion on the total antioxidant activity and carbohydrate hydrolyzing enzymes inhibitory potential of 12 functional plant-based foods. Undigested Centella asiatica showed the highest total antioxidant activity, phenolic and flavonoid content while Morus Alba and Dioscorea polystachya displayed the highest α-glucosidase and α-amylase inhibitory potential, respectively. In vitro digestion significantly (p < 0.05) increased the radical scavenging and carbohydrate hydrolyzing enzymes inhibitory activities in all plant extracts. Both phenolic (r = 0.840, p < 0.001) and flavonoid (r = 0.549, p < 0.01) contents were positively correlated with the total antioxidant activity. The activity in the aerial part of plants were significantly affected by digestion process when compared to tuber part. Principle component analysis showed that in vitro digestion contributed to 47% of total activity variation. In vitro digestion could induce the reducing power, radical scavenging, and carbohydrate hydrolyzing enzymes inhibitory potential of functional plant-based foods involving fruit, flower, seed, root, and tuber. Practical applications Functional plant-based foods with promising therapeutic potential are widely consumed in Southeast Asia countries either as raw ingredient or food additives due to their health-oriented composition and good environmental sustainability. Comparison of antioxidant activity and carbohydrate hydrolyzing enzymes inhibitory potential of functional plant-based foods before and after in vitro digestion could reveal the importance of food digestion process in modulating their health benefit. This study shows that in vitro digestion process could produce functional plant-based food products with high antioxidant and carbohydrate hydrolyzing enzymes inhibitory activity which are potential alternatives to control postprandial hyperglycemia in the early stage of type 2 diabetes with minimal side effect. The data could also serve as a reference for both consumers and food manufacturers who favor the use of functional plants as food ingredient, additives, or flavoring in food processing for health promoting purpose.