Impact of INFOGEST In Vitro Digestion on the Phytochemical Profile and Antioxidant Activity of Different Parts of Vaccinium myrtillus L.

Vaccinium myrtillus L. (bilberry) is rich in phenolic compounds whose stability may change during digestion. Methanolic extracts of the branches (B), leaves (L), and fruits (F) of two local morphotypes (M1, taller shrub form; M2, low-growing form) and of a commercial fruit sample (CF) were subjected to the INFOGEST static in vitro digestion. Total phenolic (TPC), flavonoid (TFC), and tannin contents and DPPH• and ABTS•+ scavenging activities were determined in the crude extracts and after the oral, gastric, and intestinal phases, and the crude extracts were profiled by LC–MS/MS. Digestion significantly decreased TPC and TFC in all collected samples; intestinal retention ranged from 17.6% (M2B) to 27.4% (M1B) for TPC and from 28.1% (M2B) to 55.4% (M1F) for TFC. M1B retained the highest intestinal TPC (143.28 µg GAE/mg extract), and M1L and M2L had the highest TFC (131.94 and 130.07 µg RE/mg extract). DPPH• activity decreased in leaves and branches but increased in fruits, whereas the ABTS•+ activity of fruits rose from about 10% to 95.44% (M1F). In the digested samples, ABTS•+ activity correlated negatively with TPC (r = −0.71). Quinic and chlorogenic acids predominated. Leaves and branches merit further evaluation as sources of digestion-stable phenolics.