title: Characterization of factors involved in the production of 2(E)-nonenal during mashing.
abstract: To characterize the factors involved in the production of volatile aldehydes during mashing, a model mashing experiment was done. After we inactivated the endogenous lipoxygenase (LOX) activity in the mash by mashing at 70 degrees C for 30 min, further incubation with recombinant barley LOX-1 stimulated the accumulation of 2(E)-nonenal; however, this effect was significantly reduced by boiling the mash sample. The result suggests that both LOX-1 and a heat-stable enzymatic factor are involved in the production of 2(E)-nonenal during mashing. Malt contained fatty acid hydroperoxide lyase-like activity (HPL-like activity) that transformed 9-hydroperoxy-10(E), 12(Z)-octadecadienoic and 13-hydroperoxy-9(Z), 11(E)-octadecadienoic acid into 2(E)-nonenal and hexanal, respectively. Proteinase K sensitivity tests showed that they are distinct factors. 9-HPL-like activity survived through the mashing at 70 degrees C for 30 min but was inactivated by boiling, suggesting it will be the heat-stable enzymatic factor found in the model mashing experiment.
authors.affiliation: Frontier Laboratories of Value Creation, Sapporo Breweries Ltd., 10 Okatohme, Yaizu, Shizuoka 425-0013, Japan. Hisao.Kuroda@sapporobeer.co.jp
authors.forename: Hisao
authors.initials: H
authors.lastname: Kuroda
authors.forename: Shigeki
authors.initials: S
authors.lastname: Furusho
authors.forename: Hideo
authors.initials: H
authors.lastname: Maeba
authors.forename: Masachika
authors.initials: M
authors.lastname: Takashio
mesh_terms: D000447:Aldehydes / Q000378:metabolism*; D001515:Beer; D005285:Fermentation; D001467:Hordeum / Q000201:enzymology; D008084:Lipoxygenase / Q000378:metabolism
chemical_list: D000447:Aldehydes; C013166:2-nonenal; D008084:Lipoxygenase