Obtention of Natural Dyes from Industrial Blackberry Pulp Residues (Rubus sp)

Abstract

The fruit processing industry generates large amounts of waste residues carrying environmental and financial costs. These residues, like a waste of blackberry pulp processing are composed mostly of peels and seeds rich in pigments and antioxidants, representing a potential source of natural dyes. We used complete experimental design and response surface methodology to evaluate how the quantity of solvent (20–50 mL), number of extractions (1–5), and time (10–30 min) affect the anthocyanin yield from blackberry residues (Rubus sp). The optimal conditions were 20 mL of acidified ethanol (0.1% HCI), 3 extractions, and 10 min. Under these conditions, 25.9 mg of cyanidin-3-glucoside were obtained from 100 g of blackberry residue (DW), a 59% yield. Practical Applications The economic efficiency of tropical fruit processing can be improved through the utilization of residues. Residues such as bark, seeds, and unused fruit pieces are generated in various stages of industrial processing. Species of the genus Rubus are natural sources of anthocyanins with high antioxidant capacities and strong pigmentation. The food industry produces dyes, both artificial and natural. Dyes obtained from natural sources have important biological activities and beneficial effects on health connected with antioxidant activity. Many factors influence the extraction process, including time, amount of solvent, and number of extractions. These were optimized in this study to obtain anthocyanins from processed blackberry pulp residues. Increasing the number of extractions gave a higher yield of anthocyanins. These results may be useful for industries wishing to make use of blackberry processing residues. These abundant resources and the cheap production of new food products may have positive economic and environmental impacts.