title: Quantitative evaluation of haze formation of koji and progression of internal haze by drying of koji during koji making.
abstract: The construction of an experimental system that can mimic koji making in the manufacturing setting of a sake brewery is initially required for the quantitative evaluation of mycelia grown on/in koji pellets (haze formation). Koji making with rice was investigated with a solid-state fermentation (SSF) system using a non-airflow box (NAB), which produced uniform conditions in the culture substrate with high reproducibility and allowed for the control of favorable conditions in the substrate during culture. The SSF system using NAB accurately reproduced koji making in a manufacturing setting. To evaluate haze formation during koji making, surfaces and cross sections of koji pellets obtained from koji making tests were observed using a digital microscope. Image analysis was used to distinguish between haze and non-haze sections of koji pellets, enabling the evaluation of haze formation in a batch by measuring the haze rate of a specific number of koji pellets. This method allowed us to obtain continuous and quantitative data on the time course of haze formation. Moreover, drying koji during the late stage of koji making was revealed to cause further penetration of mycelia into koji pellets (internal haze). The koji making test with the SSF system using NAB and quantitative evaluation of haze formation in a batch by image analysis is a useful method for understanding the relations between haze formation and koji making conditions.
authors.affiliation: Industrial Technology Center of Okayama Prefecture, 5301 Haga, Kita-ku, Okayama 701-1296, Japan. Electronic address: kazunari_itou@pref.okayama.lg.jp.
authors.forename: Kazunari
authors.initials: K
authors.lastname: Ito
authors.affiliation: Department of Bioindustrial Informatics and Genomics, Graduate School of Agricultural Sciences, Tohoku University, 1-1 Tsutsumidori-Amamiya-machi, Aoba-ku, Sendai 981-8555, Japan.
authors.forename: Katsuya
authors.initials: K
authors.lastname: Gomi
authors.affiliation: Fujiwara Techno-Art, 2827-3 Tomiyoshi, Kita-ku, Okayama 701-1133, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kariyama
authors.affiliation: Industrial Technology Center of Okayama Prefecture, 5301 Haga, Kita-ku, Okayama 701-1296, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Miyake
mesh_terms: D000434:Alcoholic Beverages / Q000382:microbiology; D001236:Aspergillus oryzae / Q000378:metabolism; D003890:Desiccation; D005285:Fermentation; D005511:Food Handling; D025282:Mycelium / Q000378:metabolism; D012275:Oryza / Q000382:microbiology*; D015203:Reproducibility of Results
keywords: Aspergillus oryzae; Haze formation; Internal haze; Koji drying; Koji-making