Microencapsulation of Red Grape Juice by Freeze Drying and Application in Jelly Formulation
Integrated Center for Research, Expertise and Technological Transfer in Food Industry, Faculty of Food Science and Engineering, Dunarea de Jos University of Galati, 111 Domnească Street, 800201 Galați, Romania
Received: 26 June 2019
Accepted: 25 February 2020
anthocyanin microencapsulation, freeze drying, whey protein isolate-chitosan matrix, grape juice, jelly, in vitro digestibility
The aim of this work is to obtain new food products enriched with bioactive compoundsfrom concentrated grape juice microencapsulated by freeze drying using a wheyprotein isolate- chitosan system. The obtained powder showed an encapsulation efficiencyof (86.1±4.0) %, with an anthocyanin mass fraction (expressed as cyanidin-3-O-glucosideequivalent) of (1.4±0.2) mg/g, while the total polyphenolic (expressed as gallic acid equivalents)and flavonoid (expressed as catechin equivalents) mass fractions were (3.3±0.6) and(1.6±0.5) mg/g, respectively. The confocal laser microscopy revealed the presence of theflavonoid pigments wrapped inside the matrix, whereas the anthocyanins were groupedinto large and compact clusters. The microencapsulated powder was used for jelly formulation.The new food formulations have a satisfactory anthocyanin mass fraction rangingfrom (0.03±0.01) to (0.12±0.02) mg/g, while no significant differences were observed inflavonoid content. All the value-added jelly showed appreciable antioxidant activity. Thein vitro digestibility results confirm a slow release of anthocyanins from the food matricesduring simulated gastric digestion and a significant release of the bioactive compoundsinto the gut. The addition of microencapsulated powder caused a significant decrease infirmness, cohesiveness and springiness, leading to the destabilization of the gel structure,while reducing the attraction forces between the matrix components. The sensorial analysisindicated that the panellists preferred the sample with grape juice the most.