O-10
Astringent evaluation methods of beverages using a quartz-crystal
microbalance. Although astringency plays an important role in beer taste, body and
smoothness, there have been very few reports on the measurement method for beer
astringency. The aim of this study is to develop objective evaluation methods
for the astringency of beverages using a quartz crystal microbalance (QCM). It
has been thought that stimuli of the complexes of tannins with salivary proteins
to the oral membrane cause the astringent sensations such as drying, shrinking,
drawing and puckering of the epithelium. We tried to develop two measuring
methods for the astringency of beverages using the QCM, a measurement of
reactivity of tannins with proteins using the protein-immobilized QCM and a
measurement of the interaction of tannin/peptide complexes with a lipid membrane
using the lipid-coated QCM. We found that polyphenols specifically bind with
gelatin and that the adsorption of astringent tannins on the lipid membrane
significantly increases in the presence of peptides, while NaCl (salty taste),
tartaric acid (sour taste), quinine-sulfite (bitter taste), isohumulones (bitter
taste), sucrose (sweet taste), and glutamic acid (umami taste) had no effect. It
seems that the adsorption of tannin-peptide complexes on the oral lipid membrane
could be involved the astringent sensation. The adsorption of red wine, Japanese
green tea or beer on the lipid membrane in the presence of bovine serum albumin
or gelatin successfully agreed with the astringent intensity in the sensory
evaluation.
Hirotaka Kaneda graduated from Kyushu University in 1984 with a M.S., and
then joined Sapporo Breweries, Ltd. He is currently a senior researcher in the
Brewing Research Laboratories. He worked on beer stability and received his
Ph.D. at Nagoya University in 1994. He studied human-brain function in gustation
and olfaction in the National Institute of Bioscience and Human-Technology from
1996 to 2000. He received the Eric Kneen Memorial Award from the American
Society of Brewing Chemists in 1995 and the Technical Award from the
Agricultural Chemical Society of Japan in 2000.
HIROTAKA KANEDA (1), Junji Watari (1), Masachika Takashio (1), and Yoshio
Okahata (2). (1) Brewing Research Laboratories, Sapporo Breweries, Ltd.,
Yaizu-City, Shizuoka, Japan, and (2) Department of Biomolecular Engineering, Tokyo
Institute of Technology.