Rice Koji Research Articles

Identification of 2,4,6-Trichloroanisole (TCA) causing a musty/muddy off-flavor in sake and its production in rice koji and moromi mash

2,4,6-Trichloroanisole (TCA), which has been identified as the main component responsible for the cork taint in wine, was detected in sake samples having a musty/muddy off-flavor by stir bar sorptive extraction (SBSE). We confirmed that TCA is one of the components causing this off-flavor in sake, as in other alcoholic beverages, from a sensory analysis showing the correlation between TCA concentration and the intensity of the musty/muddy off-flavor. We investigated the route of TCA production in the rice koji preparation process and in the moromi mash process for sake brewing. We found that TCA is produced mainly by the biomethylation of 2,4,6-trichlorophenol (TCP) by rice koji in brewing and that TCP originates from the wooden tools used in preparing rice koji.

Cyclopiazonic acid contamination in Japanese commercial rice koji

Cyclopiazonic acid (CPA) contamination in commercial rice koji (molded rice inoculated with koji mold) used for the production of fermented foods in Japan was surveyed using a combination of a clean-up procedure consisting of diethyl ether liquid-liquid extraction and HPLC-UV analysis (quantification limit: 25 μg/kg). Out of 38 koji samples collected from 18 prefectures, one sample was contaminated with CPA at a level of 480 μg/kg. From the CPA contaminated sample, two types of koji mold, one with white colonies and the other with yellowish green colonies, were obtained at equal incidence rates. The presence of CPA in a Japanese commercial rice koji is due to CPA production by the latter type of koji mold.

米麹から分離した乳酸菌が生産するバクテリオシン

米麹から分離した乳酸菌が生産するバクテリオシン

Cloning of a Novel Tyrosinase-Encoding Gene (melB) from Aspergillus oryzae and Its Overexpression in Solid-State Culture (Rice Koji)

Cloning of a Novel Tyrosinase-Encoding Gene (melB) from Aspergillus oryzae and Its Overexpression in Solid-State Culture (Rice Koji)

Antioxidant activity and active compounds of rice koji fermented with Aspergillus candidus

Antioxidant activity of ethyl acetate extracts from rice koji (EAERK) fermented with Aspergillus candidus CCRC 31543 was evaluated, and the antioxidant components in koji were isolated and identified. EAERK (200 μg/ml) showed a 90% inhibitory effect on peroxidation of linoleic as determined by the thiocyanate method. EAERK also showed a marked antioxidant activity on the oxidation of lard determined by using the Rancimat method. EAERK had a strong scavenging effect on the DPPH radical. Silica gel column chromatography was used to separate EAERK into eight fractions (A–H). Fractions C–F possessed significant antioxidant activity and showed more than 88% inhibition of peroxidation of linoleic acid. Fraction C was crystallized and purified to obtain compound 1. Fractions D–F were combined and re-separated by means of column chromatography and the subfraction that exhibited strong antioxidant activity was crystallized to yield purified compound 2. Compounds 1 and 2 were shown to be ergosterol and terphenyllin, respectively, on the basis of UV-vis spectral, MS and NMR analyses. Ergosterol showed no antioxidant activity on the peroxidation of linoleic acid. However, the antioxidant activity of terphenyllin was equal to that of BHA at 200 μg/ml.

有機酸が麹菌のユビキノン生産に与える影響

In order to increase the amount of ubiquinone in rice koji, several organic acids were added in the manufacturing process, resulting in a high level of effect for malic acid. However, when the amount of added malic acid was increased, the quantity of ubiquinone and mycelia in rice koji decreased under the influence of pH. The addition of 10 mmol sodium malate to rice koji showed that, although ubiquinone productivity by koji mold increased at 30%, 40% of the water adsorption rate of rice, it decreased at 50%, 60% of this.

蒸米の消化性が麹の破精に与える影響

蒸米の消化性が麹の破精に与える影響

Release of Ferulic Acid from Rice Koji in Awamori Brewing. — Note — : Masanobu Ishihara, ∗Miho Nerome, Toki Taira, Shinkichi Tawata, and Naotada Kobamoto ( Department of Bioscience and Biotechnology, Faculty of Agriculture, University of the Ryukyus, 1 Senbaru, Nishihara-cho, Okinawa 903-0213) Seibutsu-kogaku 80: 563–567. 2002

Release of Ferulic Acid from Rice Koji in Awamori Brewing. — Note — : Masanobu Ishihara, ∗Miho Nerome, Toki Taira, Shinkichi Tawata, and Naotada Kobamoto ( Department of Bioscience and Biotechnology, Faculty of Agriculture, University of the Ryukyus, 1 Senbaru, Nishihara-cho, Okinawa 903-0213) Seibutsu-kogaku 80: 563–567. 2002

Observations of boiled potato and rice koji by variable pressure SEM

Observations of boiled potato and rice koji by variable pressure SEM

A bacteriocin Produced by Pediococcus sp. NPIB-38 isolated from rice Koji

A bacteriocin Produced by Pediococcus sp. NPIB-38 isolated from rice Koji

ナイシン生産性乳酸菌を利用した米麹及び米味噌の製造方法

[in Japanese]

酵素活性が麹の破精に与える影響

酵素活性が麹の破精に与える影響

焙炒処理を利用したみりん麹の製造法 (第1報)

焙炒処理を利用したみりん麹の製造法 (第1報)

Growth of nisin-producing lactococci in cooked rice supplemented with soybean extract and its application to inhibition of Bacillus subtilis in rice miso.

Lactic acid fermentation of cooked rice and rice koji by supplementation with soybean extract (SBE) and its application to rice miso fermentation were investigated. By supplementing the cooked rice with SBE, lactic acid bacteria (LAB) grew well without any unfavorable effects on the rice such as off-flavor or coloration. Lactococcus lactis subsp. lactis IFO12007 (Lc. lactis, a producer of the bacteriocin nisin) proliferated at 10(8 to approximately 9) cells/g after 24 h of incubation and produced high activity of nisin. The fermented rice with Lc. lactis strongly inhibited not only Bacillus subtilis ATCC19659 but also the other Bacillus strains. While some strains of LAB markedly inhibited the growth of Asp. oryzae, resulting in failure of koji fermentation, Lc. lactis did not affect the growth of these molds. When Lc. lactis was used for rice miso fermentation as a lactic acid starter culture, Lc. lactis rapidly proliferated and produced high nisin activity of 6,400 IU/g, in the steamed rice, resulting in complete growth inhibition of B. subtilis, which had been inoculated at the beginning of the koji fermentation. The rice miso after 12 weeks of aging had a suitable pH, and favorable taste and color. Furthermore, hyposalting of rice miso could be done without difficulty by lactic acid fermentation of both rice and soybeans.

Productivity of Citric Acid of Aspergillus oryzae, Producing Excessive Acids, Isolated from Ina-Koji

Aspergillus oryzae N-1 and N-4 were isolated from ina-koji. Those isolates produced citric acid 4 times much as Aspergillus oryzae RIB-176, using sake making, in rice koji. Using the rice koji of 40% moisture, A. oryzae N-1 produced a great deal of citric acid in polished rice of 73.8% at 32°C and A. oryzae N-4 in polished rice of 53.6% at 37°C.

Isolation and characterization of phytase isozymes produced by Aspergillus oryzae

A mutant strain (KL-38) of Aspergillus oryzae was obtained by UV irradiation. Phytase activity of KL-38 in molded rice (koji rice) was about 2.7-fold of that obtained from the parent strain (BP-1). Phytase activity of KL-38 in the submerged culture was similar to that of BP-1. Two types of phytase were produced from koji culture: phytase I (Phy I) was produced during incubation of both koji and submerged cultures, and phytase II (Phy II) was obtained only from koji culture. Phy II production was increased in KL-38 compared with BP-1, whereas the production of Phy I was similar for both KL-38 and BP-1. This finding indicates that A. oryzae has at least two types of phytase isozyme.

Salt‐free Miso Fermentation Using Ethanol, Sugars, and Polyols

ABSTRACT:Steam‐cooked soybeans mixed with rice koji (2:1, w/w) were ground into a fine paste, combined with NaCl or sucrose, and supplemented with ethanol for miso fermentation at 28 °C for 8 wk. In products containing the same concentrations of NaCl and sucrose, proteolytic activities decreased with an increase in ethanol concentration. At the same level of ethanol (7.5% or 15%), protein hydrolysis was highest in products containing 12.5% sucrose and 0% NaCl and lowest in products containing 0% sucrose and 12.5% NaCl. NaCl enhanced and sucrose reduced the effects of ethanol on inhibition of koji proteases. A salt‐free fermentation was achieved using 15% ethanol and 12.5% sucrose. When sucrose (12.5%) was substituted by glucose, fructose, sorbitol, or glycerol and supplemented with 15% ethanol, prevention of protease inactivation by ethanol was similar to that with sucrose.

Observation of rice koji by confocal laser scanning microscopy : Hiroshige Kojima, 1Hiroshi Hasegawa, 1Tetsuro Magarifuchi, 2 and Hideo Fukuda3 ( Analytical Research Laboratory, Asahi Chemical Industry Co. Ltd., 2-1 Samejima, Fuji, Shizuoka 416–8501 1 and Liquor Technology and Development Department 2 and Sake Taste Research Group, 3 Asahi Chemical Industry Co. Ltd., 632-1 Mifuku, Ohito, Tagata, Shizuoka 410–2321 )

Observation of rice koji by confocal laser scanning microscopy : Hiroshige Kojima, 1Hiroshi Hasegawa, 1Tetsuro Magarifuchi, 2 and Hideo Fukuda3 ( Analytical Research Laboratory, Asahi Chemical Industry Co. Ltd., 2-1 Samejima, Fuji, Shizuoka 416–8501 1 and Liquor Technology and Development Department 2 and Sake Taste Research Group, 3 Asahi Chemical Industry Co. Ltd., 632-1 Mifuku, Ohito, Tagata, Shizuoka 410–2321 )

Simulation and Optimal Control for the Koji Making Process Using Genetic Algorithm

An adaptive optimal control method for koji making process on a laboratory scale was developed. The proposed strategy using the genetic algorithm (GA) consisted of two parts. 1) Estimation of the mycelial content in rice koji and the enzyme activities from current measurement variables using mathematical models. 2) Calculation of the optimal temperature trajectory for maximum activities of α-amylase and glucoamylase at the end of the cultivation time using GA based on the estimated values at step 1). Above two parts were repeatedly performed at every hour during the cultivation. As a result, using this strategy was able to perform the on-line estimate mycelial content in rice koji and adaptive optimal control of koji making process for maximum production of the enzymes.

A novel method for measurement of α-amylase activity in rice koji by capillary isoelectric focusing

A capillary isoelectric focusing (CIEF) method has been developed for the analysis of α-amylase activity in rice koji. The standards of α-amylase and rice koji extracts were successfully separated by CIEF in a large pH gradient. The α-amylase from A. oryzae was found to have pI of 3.7, as determined from the migration times of six standard proteins. A simple method has been developed for the measurement of α-amylase activity in rice koji, and the results were compared with those obtained by the official method. The coefficient of variation (C.V.) of the α-amylase assay was less than 0.5% in both intra-day and inter-day experiments. This CIEF method can be applied to the routine quality control of α-amylase activity in rice koji for the brewing process in sake production.