Optimization of the Hop Kilning Process to Improve Energy Efficiency and Recover Hop Oils

Abstract

n 2010 the company Wolf Anlagen-Technik GmbH & Co. KG (Geisenfeld) and the VLB Berlin e.V. started a two year project focusing on energy recovery during hop kilning. A heat exchanger was installed in an industrial scale hop kiln in order to decrease the consumption of primary energy. The efficiency of heat recovery using exhaust air of the hop kilning process was determined and potentially saved primary energy calculated. Heat recovery from exhaust air produces certain volumes of condensate. The collected condensate was analysed for eight selected hop oil components which were also determined in green and kilned hops. Before the heat exchange process the exhaust air was forced through a filter cartridge that contained activated carbon material. In the filter material the same eight hop oil components were quantified. For analyses and quantifications of hop oil substances an isotope dilution assay (SIDA) was used. Additionally water content and concentration of alpha- and beta-acids were determined in green and kilned hops.