Properties of antioxidants extracted by non-conventional methods from jostaberry grown in Moldova

Abstract

This research aimed to evaluate the quantitative profile and antioxidant activity (AA) of the biologically active compounds (BAC), the color parameters of the extracts obtained from frozen (FJ), freeze-dried (FDJ) and oven-dried (DJ) jostaberry by ultrasound-assisted extractions (UAE) and microwaves-assisted extractions (MAE).Jostaberry is a local product, from the south of the Republic of Moldova. After harvesting jostaberry was subjected to pretreatment processes in order to preserve the fruits by freezing, freeze-drying and oven-drying. Pretreated jostaberry was ground and mixed with hydroethanolic solution with a concentration of 60% (v/v). To establish the optimal extraction conditions, BACs were extracted by two unconventional methods: UAE with time variation, and MAE with magnetron power and time variation. The AA of jostaberry extracts was determined based on their ability to inhibit the free radical 2,2-diphenyl-1-picrylhydrazyl hydrate (DPPH) and the free radical cation 2,2-azinobis-3-ethylbenzothiazoline-6-sulfonate (ABTS). Total anthocyanins (TA) in

jostaberry extracts were measured spectrophotometrically, by the differential pH method, and color parameters were elucidated using a Chroma Meter CR-400. The results showed that non-conventional extraction methods are less destructive to anthocyanins. Oven-drying of berries reduced TA by 99.4% compared to FJ, regardless of the extraction method. Pretreatment of berries by freeze-drying and oven-drying contributed to the

AA reduction of jostaberry extracts. In all extraction conditions, the ABTS assay recorded AA values (mg TE/g DW) between 35.64 and 109.17 for FJ extracts, 45.73 and 82.22 for FDJ and 34.04 and 52.20 for DJ extracts. AA (mg TE/g DW) by the DPPH method varied between 17.70 and 35.26 for FJ, 7.50 and 7.96 of FGJ, 6.31 and 7.40 of DJ. Jostaberry pretreatment led to significant changes in all color parameters. The red tone predominates in the FJ and FDJ extracts, and the orange tone in the DJ ones. The obtained results demonstrate that jostaberry is a valuable raw material for obtaining extracts that can later be used in the food industry as natural dyes with significant antioxidant properties and high coloring capacity.