Effect of in vitro gastrointestinal digestion on the antioxidant properties of fruit and vegetable powdered smoothies reinforced with WPC80

Abstract

The development of novel powdered smoothies obtained by spray-drying (SD) technology can contribute to revaluing fruits and vegetables from seasonal surplus. The aim of this study was to evaluate the effect of in vitro gastrointestinal digestion (GID) on the retention, activity and bioaccessibility of key antioxidants of two smoothies elaborated with fruits (apple, orange and banana) or vegetables (pumpkin, apple and carrot), fortified with whey protein concentrate 80 g/100g (WPC80) and spray-dried. α-Tocopherol, ascorbic acid, polyphenol and flavonoid contents, and antioxidant capacity were determined in the smoothies reconstituted with water or semi-skimmed milk. Bioaccessibility and remaining antioxidant capacity after digestion was calculated. This study demonstrated contained smoothies were rich in sugar, protein and fibre. These smoothie powders retained most antioxidant properties intact. The reconstitution of smoothies with semi-skimmed milk means higher flavonoids and vitamin E content. In vitro GID showed a positive effect on the antioxidant properties of these smoothies by improving the bioaccessibility of TPC and favouring the scavenging ABTS radical, although the content of flavonoids and tocopherol was decreased. These results confirmed that powdered smoothies show high nutritional values and considerable antioxidant activity as a health-enhancing fortified food. Digestive simulations provide information on the potential bioaccessibility of antioxidants.