H. IMASHUKU (1); (1) Asahi Breweries, Ltd., Suita, Osaka, Japan

Poster

At the 2008 World Brewing Congress and 2011 ASBC Annual Meeting, I reported our original equipment named Pre-Isomeriser & Evaporator (PIE). It is a small kettle for boiling hops with hot water, separately from wort. We used it for removal of excessive and undesirable hoppy flavors when we reduced the total evaporation ratio during wort boiling for energy saving. In this presentation, I report another application of PIE to aroma hops added at the end of wort boiling. It improves utilization of alpha-acids and varies the characters of hop aroma in the final product. Before adding to cast wort, aroma hops were incubated in PIE, with hot water at 90–99°C, in non-boiling state, for 30–60 min. Isomerization of alpha-acids was greatly improved, therefore hop usage was reduced by 12–36%. The composition of hop terpenes was not much effected by the incubation. However, in a sensory evaluation, the aroma of final products with pre-incubated hops was evaluated as more gentle and was preferred to the control with raw hops.

Hisato Imashuku graduated with a degree in agricultural chemistry from the University of Yamaguchi, Japan. He began employment with Asahi Breweries, Ltd. in 1989 as a technical staff member in the brewing section. After he had worked at several breweries and in the laboratory, he was transferred to the Ibaraki R&D Promotion Office in 2001. He has been working at the Suita R&D Promotion Office, Production Technology Center, Asahi Breweries, Ltd. since September 2012.

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