engleski

Winery by-products : anthocyanins recovery from red grape skin by high hydrostatic pressure extraction (HHPE)

INTRODUCTION: The major residues from wine-making industry are represented by organic wastes such as grape pomace, containing seeds, skins and stems. Grape skin has been reported as a rich source of phenolic compounds (e.g. anthocyanins), even though the final recovery is highly dependent on the vinification process and the extraction method used. Anthocyanins present a very high thermal sensitivity thus extraction under lower temperatures is recommended. In this case, high hydrostatic pressure extraction (HHPE), as a novel extraction technique, has been reported as an appropriated method to improve the extractability of bioactive compounds from plant materials under lower temperature. Advantages also include shorter extraction times, higher yields, extract purity, and lower energy consumption. OBJECTIVES: The aim of this study was to investigate the effect of HHPE on the anthocyanin content in freeze-dried red grape skin pomace (cv. Teran). Optimization was carried out to obtain high extraction yields using varying high pressures (300, 400 and 500 MPa), time (3, 6.5 and 10 min), solvent type (ethanol vs. methanol) and solvent polarity (30, 50 and 70%, v/v). METHODS: Experiments were designed as a full factorial randomized experimental design. Dependent variable was total anthocyanin content (TAC), while independent variables were high pressure, time, solvent type and polarity. Individual anthocyanins were analysed by HPLC UV/Vis and expressed as malvidin-3-glucoside equivalents with an external calibration. RESULTS: Higher solvent polarity and higher pressure resulted in higher recovery of TAC, while the optimal time for extraction of TAC was 3 min. CONCLUSION: HHPE has been shown to be an efficient method for TAC recovery from red grape skin and could have potential benefits for the use in different industries.

High hydrostatic pressure extraction ; anthocyanins ; grape skins ; winery byproduct

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