Hop pellets type 90: Influence of manufacture and storage on losses of α-acids

Hop pellets type 90 are the most frequent hop products used in brewing. They are usually manufactured by drying hop cones, temporary storage of dry and pressed cones, milling and pelletising. Other possibility is a complete integration of hop harvest, cone drying, milling and pelletising in continuous process without temporary storage of pressed cones. The paper deals with the losses of bitter substances (primary α-acids) during hop cones drying, their pelletisation by two manufacturing procedures and storage in different conditions. The results of this study show that integrated procedure of hop pelletising decreases the total loss of α-acids compared to the usual procedure. During storage of hop pellets (produced by integrated procedure) the highest decrease (loss) of α-acids content was observed in pellets stored at 21 °C in the presence of air and the lowest under inert atmosphere (N 2 ) at 4 to 7 °C, respectively.