LAUSR

Abstract The grape pomace extract obtained by microwave-assisted extraction (1000 W × 10 min) was encapsulated by spray drying and freeze drying using dispersions with mixtures of whey protein isolate (WPI), gum Arabic (GA) and pectin as wall materials. Fourier transform infrared spectra analysis revealed that the microencapsulation occured, however without chemical reaction between the wall materials and the bioactive compounds from grape pomace. Thermogravimetric analysis indicated that the interactions between the wall materials resulted in powders with suitable thermal stability. The powders obtained by spray drying and freeze drying containing mixtures of WPI and GA presented the highest phenolic compounds retention (2.66 and 2.42 mg g−1 of GAE), total monomeric anthocyanins (0.346 and 0.353 mg g−1 of malvidin-3,5-diglycoside equivalent), antioxidant activity by ABTS (8.23 and 8.32 μmol g−1 of TE) and DPPH (12.64 and 10.92 μmol g−1 of TE). However, accelerated storage stability tests (at 35 and 55 °C; 75 and 90% HR), indicated that powders containing WPI, GA and pectin were more stable. Simulated gastrointestinal digestion assays demonstrated that the powders containing WPI and GA as wall materials had higher releases of anthocyanins in the intestinal phase.