title: Factors affecting phenolic acid liberation from rice grains in the sake brewing process.
abstract: Phenolic acid (ferulic and p-coumaric acid) liberation from rice grains was examined using rice samples containing phenolic acid at different levels, using two sake mash simulated digestion tests to elucidate influencing factors. Phenolic acid levels in a digest made from steamed rice using dialyzed rice koji enzymes were smaller than levels in a rice koji self-digest. Differences in phenolic acid levels among rice samples in the rice koji self-digest were larger than levels in a digest of steamed rice. In the rice koji self-digest, phenolic acid levels in the ingredient rice grains or in the formed digest related to feruloylesterase (FE) activity in the rice koji. Addition of exogenous FE to rice koji self-digestion increased phenolic acid levels, while addition of xylanase (Xyl) showed weak effects. A concerted effect of FE and Xyl was not clearly observed. Addition of ferulic acid to koji made from α-rice grains raised FE activity, but it did not increase the activity of other enzymes. A similar phenomenon was observed in an agar plate culture of koji mold. These results indicated that ferulic acid levels in ingredient rice grains correlate with FE activities of koji, as a resulut, they affect the phenolic acid levels in sake mash.
authors: Department of Biological Resource Sciences, Akita Prefectural University, Nakano Shimoshinjyo, Akita 010-0195, Japan.
authors: Toshihiko
authors: T
authors: Ito
authors: Department of Biological Resource Sciences, Akita Prefectural University, Nakano Shimoshinjyo, Akita 010-0195, Japan.
authors: Nobukazu
authors: N
authors: Suzuki
authors: Department of Biological Resource Sciences, Akita Prefectural University, Nakano Shimoshinjyo, Akita 010-0195, Japan.
authors: Airi
authors: A
authors: Nakayama
authors: Department of Biological Resource Sciences, Akita Prefectural University, Nakano Shimoshinjyo, Akita 010-0195, Japan.
authors: Masaya
authors: M
authors: Ito
authors: Department of Biological Resource Sciences, Akita Prefectural University, Nakano Shimoshinjyo, Akita 010-0195, Japan. Electronic address: hashizume@akita-pu.ac.jp.
authors: Katsumi
authors: K
authors: Hashizume
mesh_terms: D000434:Alcoholic Beverages / Q000032:analysis*; D002265:Carboxylic Ester Hydrolases / Q000378:metabolism; D003373:Coumaric Acids / Q000378:metabolism / Q000494:pharmacology; D043364:Endo-1,4-beta Xylanases / Q000378:metabolism; D062385:Hydroxybenzoates / Q000378:metabolism*; D012275:Oryza / Q000201:enzymology / Q000378:metabolism*; D011422:Propionates; D013227:Steam
chemical_list: D003373:Coumaric Acids; D062385:Hydroxybenzoates; D011422:Propionates; D013227:Steam; C004999:ferulic acid; D002265:Carboxylic Ester Hydrolases; C070196:feruloyl esterase; D043364:Endo-1,4-beta Xylanases; C017616:phenolic acid; C495469:p-coumaric acid
keywords: Feruloylesterase; Koji; Phenolic acid; Rice; Sake