Effects of extraction conditions on bioactive anthocyanin content of Vaccinium corymbosum in the perspective of food applications

摘要

Bioflavonoids, in particular anthocyanins have made the topic of many scientific research, mainly for two reasons: their beneficial effects on human health and applications as potential sources of natural food dyes. Natural extracts of these pigments may also find useful application for textiles dying, as an eco-friendly alternative to synthetic dyes. The aim of the present paper was to apply conventional extraction procedures in order to isolate an enriched crude extract of pigments from highbush blueberries (Vaccinium corymbosum L.). Water, hydroalcoholic solution and acidified alcoholic solvent were tested to extract anthocyanins by a discontinuous process. Also, temperatures of 4 °C, 30 °C and 50 °C at 2 hours time of extraction, and storage at -18 °C were tested. Concentration of monomeric anthocyanins was performed by the spectrophotometric pH differential method. Added hydrochloric acid in ethanol system was found more efficient than acetic acid regarding the extraction yield. The highest recovered anthocyanin content was obtained with 50 % ethanol (148.51 mg 100 g"' FW), while the lowest one was obtained with water (3.24 mg 100 g~(-1) FW). The applied elevated temperatures showed better extraction yield as diffusion rate and solubility of analytes in solvents are greater. Storage of fresh materials at freezing temperature showed an increase of the initial content of anthocyanins. Through the assessment of the influence of solvents and extraction temperatures, our results showed that anthocyanin extraction from Vaccinium corymbosum should be conducted under the following conditions: temperature of 50 °C, extraction time 2 hours, with solvent containing 50 % ethanol, and protection against light.