Stability of the phenolic compounds and antioxidant capacity of five fruit (apple, orange, grape, pomelo and kiwi) juices during in vitro‐simulated gastrointestinal digestion

Summary The in vitro digestive stability of phenolic compounds and the antioxidant capacity of five kinds of commonly consumed fruit juices in the daily diet, including apple juice ( AJ ), orange juice ( OJ ), grape juice ( GJ ), pomelo juice ( PJ ) and kiwifruit juice ( KJ ), were studied. Following in vitro digestion, the total phenolic ( TP ) content of fruit juices decreased to different extents by 35%, 25.3%, 23.5%, 22.2% and 7.8% for KJ , OJ , PJ , GJ and AJ , respectively. The individual phenolic content showed similar changes to the TP content, showing reductions of naringenin‐trisaccharide in OJ and PJ , epicatechin in GJ , and chlorogenic acid in AJ by 43.74%, 27.59%, 47.11% and 33.28%, respectively. Conversely, the antioxidant capacity of fruit juices during digestion measured by ABTS assay increased from 4.79% to 35.53%, except in KJ , which decreased by 19.34%. These results show the health benefits of fruit juices after processing and contribute towards establishing suitable dietary recommendations.