Effects of Encapsulation and In Vitro Digestion on Anthocyanin Composition and Antioxidant Activity of Raspberry Juice Powder

Abstract

Microbeads of raspberry extract were produced using encapsulation matrices alginate + pea protein isolate + psyllium mucilage, alginate + pea protein isolate + psyllium mucilage + okra, and alginate + pea protein isolate + psyllium mucilage + Aloe ferox gel + gallic acid using freeze-drying method. The microbeads were characterised and assessed for their effectiveness on the release, bioaccessibility, of anthocyanin components and antioxidant activities during in vitro digestion. Alginate + pea protein isolate + psyllium mucilage + Aloe ferox gel + gallic acid matrix showed the highest encapsulation efficiency of 91.60% while the lowest encapsulation efficiency was observed in alginate + pea protein isolate + psyllium mucilage + okra (69.94%). Scanning electron microscope images revealed spherical shapes and varying surface morphologies for different encapsulation matrices. Despite the differences observed in Fourier transform infrared spectra, microbeads showed similar thermal degradation patterns. X-ray diffractograms showed amorphous structures for different encapsulation matrices. Comparatively, alginate+ pea protein isolate + psyllium mucilage + Aloe ferox gel + gallic acid microbeads exhibited the highest bioaccessibility for total phenols (93.14%), cyanidin-3-O-sophoroside (54.61%), and cyanidin-3-O-glucoside (55.30%). The encapsulation matrices of different biopolymer combinations (alginate+ pea protein isolate+ psyllium mucilage, alginate + pea protein isolate + psyllium mucilage + okra, and alginate + pea protein isolate + psyllium mucilage + Aloe ferox gel + gallic acid) enhanced anthocyanin stability and protected it against in vitro degradation of bioactive compounds.