P-20
Application of compact high-performance ESR for malt quality
estimation. The application of a compact high-performance electron spin resonance (ESR)
instrument for quality control during malting was studied. The ESR can analyze
not only liquid but also solid samples without any complicated procedures. The
malting of 90 kg barley samples were performed under several conditions using
the pilot malting plant in the Brewing Research Laboratories. The green malt was
lyophilized before its analysis. Five whole grains or 0.2 g of ground samples
were used for the analysis. The ESR spectrum of the green malt or malt was
measured using Mn(^2+) as an internal standard with a compact high-performance
ESR spectrometer (ES-10, Nikkiso Co., Ltd., Tokyo). Routine malt quality tests
were also carried out according to the methods of the EBC. Barley, green malt
and malt showed one peak signal derived from a stable organic radical (g =
2.005). The signal intensity of the green malt or malt increased with the
increasing steeping degree and/or germination periods. The signal intensity of
the malt showed a correlation with several parameters indicating malt
modification, such as the Kohlbach index, Hartong index at 45°C, diastatic
power, viscosity, friability, and beta-glucan contents. Therefore, it was
expected that the ESR analysis could be used as a simple quality control
technique in malting.
KIYOSHI TAKOI graduated in 1989 from Tohoku University with an MS in
agricultural chemistry and joined the Brewing Research Laboratories of Sapporo
Breweries, Ltd. He is currently Lead Biochemist in the Brewing Technology Dept.
at Sapporo. He has worked in the pilot malting and brewing since 1999.
KIYOSHI TAKOI (1), Hirotaka Kaneda (1), Toru Kikuchi (1), Junji Watari (1),
Masachika Takashio (1), Junko Yoshimura (2), Naoko Nishita (2), Hiromi Yamazaki
(2), and Junzo Yana (2). (1) Sapporo Breweries Ltd., Brewing Research
Laboratories, and (2) Nikkiso Co., Ltd., Research & Development Center.