Technical Session 04: Hops II Session
Seiichi Takishita, Asahi Breweries, Ltd.
Co-author(s): Hisato Imashuku, Asahi Breweries, Ltd., Japan; Martin
Krottenthaler, Hochschule Weihenstephan-Triesdorf, Germany; Thomas
Becker, Technische Universität München, Germany
ABSTRACT: Our colleague, Hisato Imashuku, presented PIE
(pre-isomerizer and evaporator) at WBC 2008. This is a system in which
hops are boiled with hot water separately from the wort. By using this
system, we can save energy, improve the hop alpha-acids utilization, and
so on. In this study, further improvement of the alpha-acids
utilization using PIE was investigated, and the bitter quality of beer
was evaluated. First, optimization of hop pellet PIE treatment
conditions at the laboratory scale was conducted. In consequence,
boiling 60 min under pH 8.0 using KOH (at the onset of boiling) was the
best condition. Secondly, some brewing trails with 70% malts and 30%
syrup adapting the abovementioned PIE condition were done at a 60-L
scale pilot plant. The influence of the time when PIE-boiled hops are
dosed to wort/beer, the influence of aged hops, and the influence of
different hop varieties were the focus of the study. Concerning the time
of dosing PIE-boiled hops, there was no significant difference in
alpha-acids utilization with different dosing time, during boiling, at
the beginning of fermentation and at the beginning of maturation.
Maximum alpha-acids utilization was approx. 67%, which was only approx. 2
and 10% lower than using isomerized kettle extract and isomerized
extract, respectively, and >1.5 times higher than conventional hop
dosing. There was no significant difference in the bitter quality of
beer, in spite of the different dosing times for PIE-boiled hops.
Concerning the influence of aged hops and different hop varieties, there
was no significant difference in the rating of bitter quality between
using PIE and the conventional method. Nevertheless the character of
bitterness changed slightly, and we presume that it is related to the
amount of non-isohumulone bittering compounds in the beer. As a result,
this could make it possible to control the character of bitterness in
beer.
Seiichi Takishita graduated in 1999 with a master’s
degree in agricultural and life sciences from the University of Tokyo,
Japan. He began employment with Asahi Breweries, Ltd. in 1999 as a
technical staff member in the brewing section. After he had worked at
several of the breweries and Development Laboratories for alcoholic
beverages, he worked as a visiting researcher at the Technology
University of Munich from 2010 to 2012.
VIEW PRESENTATION 11
