Antioxidant potential of jostaberry phytochemicals encapsulated in biopolymer matrices during storage

Abstract

The jostaberry (Ribes × nidigrolaria) hybrid is a rich source of phytochemicals with high antioxidant activity (AA). However, due to the thick skin and seeds, the whole fruits are rejected by some consumers, and their incorporation into food products may negatively affect the sensory properties. Furthermore, after drying, including freeze-drying, jostaberries become sticky and gummy, making them unsuitable for grinding into powder. In this context, the present study aims to improve the handling properties and evaluate the biological value, antioxidant potential, physicochemical characteristics, and color parameters of biopolymer microparticles enriched with biologically active compounds (BACs) from jostaberry during freeze-drying and subsequent storage in the dark under ambient conditions (22 ± 1 °C, relative humidity ≤ 75%). For this, jostaberry extract (JE) was encapsulated using combinations of biocompatible carriers: maltodextrin-nutriose (resistant dextrin)-pectin and maltodextrin-nutriose-sodium alginate. The encapsulated products were freeze-dried to obtain microparticles (MNPJ and MNAJ) with yields of 87.7% and 88.9%, respectively. It was found that the biopolymer matrix provided superior protection for the encapsulated BACs during freeze-drying compared to the fruit matrix. The AA determined in MNPJ and MNAJ microparticles by DPPH and ABTS assays decreased only 1.1 and 1.5 times, respectively, while in freeze-dried jostaberry, AA showed a decrease of 3.7 times (DPPH) and 2.3 times (ABTS), respectively. Tukey’s post hoc HSD analysis revealed multiple significant differences (p < 0.05) between storage intervals for all measured parameters. While DPPH and ABTS values progressively decreased, total polyphenols (TPC) and anthocyanins concentration (TAC) and their retention efficiency showed changes after specific storage intervals (3, 6 and 12 months). After 12 months of storage, TPC and TAC decreased by 8.2% and 12.2% in MNPJ and by 3.3% and 3.9% in MNAJ, respectively. Therefore, microparticles containing sodium alginate showed the lowest BAC loss during storage. The obtained results reveal that after 12 months of storage, the color and physicochemical properties of the microparticles remained largely stable.