P-14
Development of novel barley with improved beer foam and flavor stability—The impact of lipoxygenase-1-less barley in brewing industry
Presenter: Kiyoshi Takoi, Sapporo Breweries Ltd., Yaizu, Shizuoka, Japan
Coauthors: Naohiko Hirota, Sapporo Breweries Ltd., Ota, Gunma, Japan; Hisao Kuroda, Sapporo Breweries Ltd., Yaizu, Shizuoka, Japan; Takafumi Kaneko, Sapporo Breweries Ltd., Ota, Gunma, Japan; Hirotaka Kaneda, Sapporo Breweries Ltd., Yaizu, Shizuoka, Japan; Ikuya Yoshida, Sapporo Breweries Ltd., Yaizu, Shizuoka, Japan; Masachika Takashio, Sapporo Breweries Ltd., Yaizu, Shizuoka, Japan; Kazutoshi Ito, Sapporo Breweries Ltd., Ota, Gunma, Japan; Kazuyoshi Takeda, Okayama University, Kurashiki, Okayama, Japan

We have shown that the flavor and foam of beer can be improved by using a barley line lacking lipoxygenase-1 (LOX-1) as malt. However, we did not know the direct screening method of LOX-1-less trait for breeding and other applications of the LOX-1-less barley (LOX-less barley) in brewing. Here, we report the molecular basis of LOX-1 deficiency in the barley line, and the brewing performance of the LOX-less barley as adjunct. A genomic sequence of the LOX-1 gene isolated from the LOX-less barley line (SBOU2) was determined. The sequence at the splicing donor site of the fifth intron of the clone was mutated from the consensus sequence (GT) to AT. The replacement of the base forms a new stop codon. RT-PCR analysis showed that the amplified fragment of the LOX-1 cDNA from SBOU2 was longer than that of the nonmutant barley. The cDNA clone contains the whole fifth intron sequence. Therefore, based on these results, we conclude that the molecular basis of the LOX-1 deficiency in SBOU2 line is attributed to a single nucleotide mutation at the splicing donor site of the fifth intron, which causes splicing disorder and forms a functional stop codon. To evaluate the brewing performance of a LOX-less barley line as adjunct, samples were prepared from two F5 populations derived from the same cross: LOX-plus and LOX-minus. Trial brewing was carried out with these samples as adjunct. The THOD content in the LOX-minus beer (happo-shu) was reduced to 33% of that in the LOX-plus beer. Moreover, the NIBEM value, an index of beer foam stability, was prolonged for 17 s. After storage at 37°C for 1 week, the trans-2-nonenal level of the LOX-minus beer was lower than that of the LOX-plus beer by 44%. In the sensory evaluation, well-trained panel members recognized a significant superiority of the LOX-minus beer in terms of "flavor" and "total aging" (significant at the 5% probability level). The results of the trial brewing suggest that the LOX-less barley can be effectively used not only as malt but also as adjunct to improve flavor and foam stability of beer. These satisfactory results in the trial brewing indicate that the LOX-less barley will become one of the powerful tools to improve the flavor and foam stabilities of beer. We are incorporating the LOX-less trait into several advanced barley varieties worldwide.

Previously presented at the 30th Congress of the European Brewery Convention on May 14–19, 2005, in Prague, Czech Republic.

Kiyoshi Takoi graduated in 1989 from Tohoku University with an M.S. degree in agricultural chemistry and joined the Brewing Research Laboratories of Sapporo Breweries Ltd. He is currently general manager in the Production & Technology Development Center at Sapporo. He has been engaged in the pilot malting and brewing since 1999.