ANTIOXIDANT CHARACTERISTICS OF METHANOL AND ETHANOL EXTRACTS OF SELECTED VARIETIES OF HUMULUS LUPULUS

Abstract

Hops are an important ingredient in beer composition. In recent times, attention has been focused on the positive effects of hops as a plant with a high content of substances with antioxidant properties. Knowing the total concentration of polyphenols or the total antioxidant capacity of individual hop varieties could contribute to the creation of the so-called functional beer with a high content of biologically active substances. The results showed a connection between the content of α-bitter acids and the total content of polyphenols in hops. The highest concentration of polyphenols, corresponding to 2.52 g/dm³ of gallic acid, was the ethanol extract of the Polaris variety, prepared at a temperature of 100 °C from cryo-pulverized hops, whose content of α-bitter acids is up to 20 %. With the use of the ABTS cationic radical higher antioxidant activity, on average, was determined in the methanolic extracts, on the other hand, with the use of the DPPH radical, the ethanolic extracts showed a higher antioxidant activity. Using the ABTS method, the highest total antioxidant capacity was determined in the methanol extract of the Polaris variety, prepared from pulverized hops at a temperature of 100 °C, namely 25.50 mmol/dm³ Trolox equivalents. The DPPH method had the highest antioxidant efficiency, 94.9 %, determined in the methanol extract of the Polaris variety prepared from cryo-pulverized hops by extraction at a temperature of 100 °C. By comparing the results of analyzes of several hop varieties, the Polaris variety appears to be suitable for the preparation of functional beer.