Impact of an in vitro dynamic gastrointestinal digestion on phenolic compounds and antioxidant capacity of apple treated by high-pressure processing

Abstract

The aim was to evaluate the effect of an in vitro dynamic gastrointestinal digestion (GID) on the recovery index and bioaccessibility, the stability of phenolic compounds, and the changes in antioxidant capacity (AC) of apples 'Golden Delicious' treated by high-pressure processing (HPP-treated). All the phenolic compounds decreased during GID in untreated and HPP-treated apple and in consequence a decrease in the antioxidant capacity (DPPH, ABTS+, TP-FC and FRAP) and in the effect on the inhibitory capacity of lipoxygenase (LOX) and xanthine oxidase (XO) activities was also observed. The dynamic-GID increased the release of quercetin-aglycone and led to low quercetin-glycosides bioaccessibility (~10%). HPP-treated compared to untreated-apple presented higher recovery index for hydroxycinnamic acids (~67% and 52%) and higher bioaccessibility for hydroxycinnamic acids (40% and 31%) and dihydrochalcones (30% and 19.5%). The bioaccessible fraction of HPP-treated apple showed a high retention of the undigested AC: 24% (DPPH), 14% (ABTS+), 86% (TP-FC), 48% (FRAP) and the 68% and 100% of XO and LOX inhibitory capacities. Industrial relevanceThe consumer is willing to pay for added value in functional foods or ingredients that represent a substantial improvement in terms of quality of life and health. Therefore, functional food industries need to find valid methods to guarantee that the bioactive compounds present in the functional food or ingredient are effective and should do the biological action for which they were designed. The functional food industry relies more and more on the technology implemented in in vitro digestion models that simulate gastrointestinal digestion, to assess the bioaccessibility of bioactive compounds as the first step to investigate their bioavailability. The current study provides relevant information for the use dynamic gastrointestinal models instead of the more frequently employed static models to obtain more exact data about the bioaccessibility of phenolic compounds of a functional apple ingredient obtained by high-pressure processing of apples pieces with peels.These results should provide realistic information to the functional food industry about the amounts should be consumed of a certain functional food or ingredient to achieve the promised biological effect. This information can suppose an added value to these functional foods which will revert in the economic improvement and the prestige of the food industry.