Chemometric analysis on the stability of bioactive compounds and antioxidant profile of plant-based foods subjected to digestion and different drying treatment

Abstract

This study aimed to investigate the impact of in vitro digestion on phytochemicals with antioxidant activity in four commercial plant-based foods dried with three different methods. Fresh Aloe vera (L.) Burm. f. rinds, Centella asiatica (L.) Urban stem and leaves, Cymbopogon citratus (DC.) Stapf stalks, and Psophocarpus tetragonolobus (L.) DC. pods were subjected to hot air oven drying, microwave drying, and freeze drying prior to in vitro digestion. The total flavonoids, phenolics, tannins, polysaccharides and total antioxidant activities, including ferric reducing antioxidant power and radical scavenging activities of digested plant samples were compared to their non-digested counterparts. In general, the digestion process reduced plant's phenolics, polysaccharides and antioxidant activities by 6 %–94 %, irrespective of plant species and drying methods. Among the digested plant samples, freeze-dried C. asiatica and C. citratus retained the highest flavonoid content. Although the polysaccharide content in freeze-dried A. vera samples decreased by 94 % after digestion, this trend was not seen in the flavonoid and tannin content of hot air-dried P. tetragonolobus samples. Principal component analysis showed that digestion induced 58 % of antioxidant activity variation, while drying contributed to 17 % of total activity variation. Considering the overall antioxidant index and impact of digestion, freeze drying was preferred for A. vera, C. asiatica, and C. citratus, while hot air oven drying was ideal for P. tetragonolobus. The current study has demonstrated the importance of considering the impact of digestion process when evaluating suitable drying methods to yield plant-based foods with optimal antioxidant activity.