Supercritical fluid extraction of hops

Abstract

Five cultivars of hop were extracted by the method of supercritical fluid extraction using carbon dioxide (SFE-CO2) as extractant. The extraction (50 g of hop sample using a CO2 flow rate of 97.725 L/h) was done in the two steps: 1. extraction at 150 bar and 40°C for 2.5 h (sample of series A was obtained) and, after that, the same sample of hop was extracted in the second step: 2. extraction at 300 bar and 40 °C for 2.5 h (sample of series B was obtained). The Magnum cultivar was chosen for the investigation of the extraction kinetics. For the qualitative and quantitative analysis of the obtained hop extracts, the GC-MS method was used. Two of four themost common compounds of hop aroma (α-humulene and β- caryophyllene) were detected in samples of series A. In addition, isomerized α-acids and a high content of β-acids were detected. The α-acids content in the samples of series B was the highest in the extract of the Magnum cultivar (it is a bitter variety of hop). The low contents of α-acids in all the other hop samples resulted in extracts with low α-acids content, i.e., that contents were under the prescribed α-acids content.