Research of Extraction of Biologically Active Substances From Grape Pomace by the Subcritical Water

The process of extracting biologically active substances from the grape pomace of grape variety Moldova has been studied. The presence of gallic acid and furfural was identified. It is shown that the temperature of the extraction process has the greatest influence on the yield of biologically active substances from grape pomace. The influence of process parameters of extraction (the size of the fraction of dry grape pomace, temperature, pressure, liquid-solid ratio) on the antioxidant activity of the extracts, the yield of dry matter, the total yield of polyphenols, tartaric (wine) compounds, reducing substances is determined. It was established that the use of dry grape pomace of 3 mm fraction ensures the maximum yield of target products. Rational parameters of this process are determined. The maximum yield of dry substances during the SCW extraction of GP is provided by the following process parameters: T=150–160 ºC, τ=90 min, P=12 MPa and liquid-solid ratio of 1:10. Rational process parameters of SCW extraction of GP during the extraction of total polyphenols: T=100–110 ºC, τ=60 min, P=12 MPa and liquid-solid ratio of 1:10. The extracts obtained with these parameters have a high antioxidant activity – 94.01 %. Rational process parameters of SCW extraction of GP during the extraction of reducing substances: T=150–160 ºC, τ=90 min, P=12 MPa and liquid-solid ratio of 1:10. These parameters provide extraction of up to 50 % of reducing substances. The high titrated acidity of the extracts obtained (6.649, 0.1 mol/l NaOH per 1 g of extract, ml) is provided by the extraction of GP with the following process parameters: T=150–160 ºC, τ=90 min, P=12 MPa and liquid-solid ratio of 1: