title: Characterization of factors that transform linoleic acid into di- and trihydroxyoctadecenoic acids in mash.
abstract: The qualities of beer are deteriorated by the presence of either di- or trihydroxyoctadecenoic acids, which reduce the beer 'head' and produce an astringent flavor. In this study we found that native extracts of malt mash transformed linoleic acid into di- and trihydroxyoctadecenoic acids, but this transforming activity and lipoxygenase activity were inactivated by heating the mash at 70 degrees C for 30 min. Recombinant barley lipoxygenase 1 was not able to transform linoleic acid into di- and trihydroxyoctadecenoic acids. The transforming activity of mash extract heated at 70 degrees C for 30 min could be restored by the addition of recombinant barley lipoxygenase 1; in contrast, the activity of boiled mash extract was not substantially restored by the recombinant enzyme. These results indicate that di- and trihydroxyoctadecenoic acids are generated from linoleic acid by both lipoxygenase and a heat-stable enzymatic factor present in the mash.
authors.affiliation: Brewing Research Laboratories, Sapporo Breweries Ltd., 10 Okatome, Yaizu, Shizuoka 425-0013, Japan. Hisao.Kuroda@sapporobeer.co.jp
authors.forename: Hisao
authors.initials: H
authors.lastname: Kuroda
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Kobayashi
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Kaneda
authors.forename: Junji
authors.initials: J
authors.lastname: Watari
authors.forename: Masachika
authors.initials: M
authors.lastname: Takashio