Technical Session 13: Hops III Session
Hiromasa Yamauchi, Suntory Business Expert Ltd., 57 Imaikami-cho, Nakahara-ku, Kawasaki, Japan
Co-author(s): Yuri Mukouzaka, Susumu Furukubo, Kazuhiko Nakashima,
and Takayuki Taniguchi, Suntory Business Expert Ltd., Kawasaki, Japan;
Masami Harada, Suntory Holdings Ltd., Tokyo, Japan
ABSTRACT: Hop is one of the key raw materials affecting
beer quality, and the correct identification of hop varieties is very
important. Generally, hop varieties are identified by differences in
cone structures, sensory analysis, and the content of substances such as
alpha-acids and essential oils. However, these methods have limitations
because the content of the substances in hop can be variable depending
on cultivation conditions and pelletized hop cannot be identified by
observation of external appearance. Several DNA analysis techniques have
been developed for the identification of hop varieties, e.g., SSR
method, RAPD method, RFLP method, AFLP method, etc., which generally
utilize the polymorphism of PCR-amplified products or restriction
enzyme-digested fragments of hop DNA. These methods are generally
complicated and have limitations to detection of mixing of other
varieties. Analysis of SNPs (single nucleotide polymorphisms) in genome
DNA can be a powerful tool for the identification of varieties. However,
in order to obtain sufficient SNP positions for the identification of
many varieties, large amounts of DNA sequences should be needed. In
recent years, high throughput DNA sequencing technology has been
developed using a so-called “next generation sequencer.” Using this
technique, we tried to develop SNP-based identification method for hop
varieties. Large amounts of DNA sequence data in several European hop
varieties were obtained using the next generation sequencer. By
comparing DNA sequences between the varieties, several SNP-rich DNA
regions in hop genome were selected as candidates for identification
markers. DNA sequences of these regions in other European hop varieties
were also determined using the traditional Sanger method, and it was
evaluated whether these regions could be DNA markers for the
identification of all varieties tested. As a result, 14 hop varieties
could be identified by using four SNP-rich DNA regions. Moreover, it was
studied whether a mixture of two varieties could be correctly evaluated
by this method. A hop pellet sample of one variety was mixed with that
of another variety at various ratios (0, 5, 10, 50, and 100%), and their
DNA was extracted to sequence the DNA marker regions. By observing the
electropherogram of SNP positions, it was suggested that the mixture of
with the other variety at a 5% level could be detected. A quantitative
determination method of mixture rate can be expected using DNA
techniques, such as quantitative real-time PCR, etc. Because this method
utilizes the DNA sequence itself, it could be a simple and reproducible
tool for the identification of hope varieties.
Hiromasa
Yamauchi received his doctor of agriculture degree from the University
of Tokyo in 1991. In 1978, he began employment with Suntory Ltd. as a
researcher in the Institute for Alcoholic Beverages, and later, in the
Institute for Fundamental Research. He conducted research on bacteria,
yeast, fungi, and plant genetics and biochemistry. In 1996, he attended
the 62nd ASBC Annual Meeting and made a presentation on “Rapid Methods
of Detecting Beer Spoilage Yeasts by Using Polymerase Chain Reaction.”
Since April 2001, he has served in the Quality Assurance Division, in
which he has developed several identification techniques for plant and
living organisms using DNA analysis.
VIEW PRESENTATION 44
