Yuji Teramoto

Solubilization of a novel isoflavone glycoside-hydrolyzing β-glucosidase from Lactobacillus casei subsp. rhamnosus

A novel isoflavone glycoside-hydrolyzing β-glucosidase produced by Lactobacillus casei subsp. rhamnosus IFO 3425 was solubilized by ultrasonic disruption of the cells in the presence of 2-mercaptoethanol and sorbitol as stabilizer. The β-glucosidase from L. casei subsp. rhamnosus specifically hydrolyzed soybean isoflavone glycosides, namely, daidzin and genistin, converting them to daidzein and genistein, respectively. By contrast, a commercial preparation of almond emulsin β-glucosidase could not hydrolyze these soybean isoflavone glycosides. The undesirably bitter and astringent isoflavone glycosides in soybean were decomposed for the first time with this novel β-glucosidase, an enzyme which has hitherto been considered difficult to solubilize, produced by a lactic acid bacterium.

Hydrolysis of isoflavones in soybean cooked syrup by Lactobacillus casei subsp. rhamnosus IFO 3425

Abstract A novel cheese-like fermented food, designated soybean cooked syrup cheese (SCSC), was produced by lactic acid fermentation of soybean cooked syrup (SCS) generated during production of natto (a Japanese fermented soybean preparation). SCS contains two characteristic compounds, daidzin (35.1 mg/100 g SCS) and genistin (40.5 mg/100 g SCS), which originate in soybean seeds and have an unpleasant taste. These two isoflavone glycosides were properly decomposed during fermentation by every lactic acid bacterium tested. In particular, Lactobacillus casei subsp. rhamnosus IFO 3425, which produces β-glucosidase, showed significant hydrolytic activity against the isoflavone glycosides in the SCS. Thus, a useless industrial byproduct was converted to a cheese-like fermented food by an economical and uncomplicated procedure.

A Novel Raw-Starch-Digesting Yeast α-Amylase from Lipomyces starkeyi HN-606

An amylolytic yeast strain, isolated from Thai Loogpang Lauw and identified as Lipomyces starkeyi HN-606, was found to produce a novel yeast α -amylase characteristically showing raw-starch digestibility almost to the same extent as the commercial amylolytic Aspergillus , but with a lower culture temperature of 15°C rather than 25°C as optimal for growth. The yeast α -amylase (MW 56,000) was adsorbed onto raw corn-starch and could digest it to form glucose, maltose and maltotriose. α -Cyclodextrin at less than 10 mM completely inhibited the raw-starch adsorption and digestion with a K l value of 0.38 mM, but could hardly inhibit gelatinized-starch hydrolysis.

Batchwise ethanol fermentation with shochu distillery waste.

Abstract A novel vacuum distillation procedure at low temperature (35–40°C) was applied to shochu distillation to produce a shochu with a mild aroma. The resulting kome (rice) shochu distillery waste contained a large amount of viable yeast (7 × 10 6 cells/ml), glucoamylase activity (70 U/ml), acid protease activity (720 U/ml), and neutral protease activity (420 U/ml). Secondary ethanol fermentation of the mash composed only of glucose as a carbon source and kome or mugi (barley) shochu distillery waste was properly effected. About 10% of ethanol (v/v) was produced in the fermented mash at 30°C within 3 d. In contrast, distillery waste discharged by conventional distillation at high temperature (55–60°C) could not be used for secondary ethanol fermentation at all. The filtrate of secondarily-fermented distillery waste, containing ethanol and possessing a fine aroma fortified with higher alcohols and volatile esters during ethanol fermentation, could be useful for the production of a mirin -like liquor for cooking, Akazake , a characteristic red-colored, sweet alcoholic beverage produced in Kumamoto prefecture only, and a bath additive containing ethanol, a fine aroma, and enzymes. The solid cake of the fermented mash could be used in the same way as conventional sake-kasu, sake -cake. Here, a novel system of utilizing shochu distillery waste, conventionally treated as wastewater, was established economically using a simple vacuum distillation procedure without a need of any complicated process.

Design of microbial processes and manufactures based on the specialities and traditions of a region: A Kumamoto case

Efforts have been made to produce two types of ancient and/or novel alcoholic beverages as follows. (i) Sprouting-rice wine, a legendary and mysterious alcoholic beverage that dates back to antiquity in Japan, was successfully reproduced using sprouting rice as a saccharifying agent. (ii) Red-rice wine, a novel alcoholic beverage, was made from red-rice by ethanol fermentation without cooking. Attempts were also made to utilize by-products of the brewing process and from food industries as starting materials for new products. (i) Shochu distillery waste was successfully used for production of various alcoholic beverages with red-rice bran and chrysanthemum flowers (Higo-giku) and for semicontinuous ethanol fermentation. (ii) Soybean cooked-syrup, discharged from a natto factory, was successfully used for production of a cheese-like food and a yogurt-like drink. Characteristic alcoholic beverages and foods closely related to the brewing and food industries in Kumamoto Prefecture were produced from an example of cooperation of bioindustry, public research institution and educational institution. Attempts were also made to utilize industrial by-products and waste as materials for new products with the intent of developing regional biorecycling systems for the brewing and food industries.

Improvement of the quality of aromatic red rice wine

Abstract The aromatic red rice wine produced economically by uncooked ethanol fermentation of aromatic red rice (Oryza sativa var. Indica, Tapol) using a glucoamylase preparation AN-2 (produced by Aspergillus niger) contained a larger amount of aromatic components such as isobutyl alcohol and ethyl acetate than rice wine made from a mixture of glucose and aromatic red rice without glucoamylase AN-2. The red color of rice wine made from aromatic red rice using glucoamylase AN-2, however, was not as brilliant as that of rice wine produced without glucoamylase AN-2. Spectrophotometric analysis revealed that the specific absorbance at 530 nm of the aromatic red rice pigment was drastically decreased in the rice wine produced with glucoamylase AN-2. The red pigment of the aromatic red rice wine was partially decolorized enzymatically with the liberation of glucose by the action of β-glucosidase contained in the glucoamylase AN-2. Sumizyme (a glucoamylase produced by Rhizopus sp.) containing a lower amount of β-glucosidase, however, did not decolorize the characteristic red color of aromatic red rice wine. The aromatic red rice wine made with Kyokai no. 9 yeast was judged to have an excellent quality by organoleptic testing and was found to contain a 1.6 times higher amount of ethyl acetate by gas chromatographic analysis. Here, the brilliant red-colored, aroma fortified, wine-like alcoholic beverage was newly developed with aromatic red rice, Sumizyme glucoamylase, and Kyokai no. 9 yeast.

Practical soy sauce production using a mixed Koji-making system

Abstract In order to produce raw soy sauce, a mixed culture of 3,600 kg defatted soybean, 3,600 kg wheat grain, and 3.8 kg mixed tane-koji was prepared with Aspergillus oryzae K2 (length of conidiophores, about 350 μm) and a late-conidiating strain, A. oryzae HG (length of conidiophores, about 2,500 μm). The resulting mixed culture showed high glutaminase activity (5.5 units/g dry koji) compared with a monoculture of strain K2 (1.8 units/g dry koji). In addition, the number of conidia contained in the mixed culture (2.5 × 107/g dry koji) drastically decreased compared with those in the monoculture of strain K2 (1.3×108/g dry koji), thus resolving the serious problem of conidia dust contaminating the working environment during the koji-making process. The mixed culture was then combined with 13,000 l of 23% NaCl solution and fermented for 180 d. The glutamic acid content of the raw soy sauce made with mixed culture was 1.25 times higher than that of the raw of soy sauce made by the conventional soy sauce making process.

Ethanol Fermentation of Aromatic Red Rice without Cooking, Studies on Red Rice Wine Brewing (Part 1)

Abstract Using aromatic red rice (Oryza sativa var. Indica, Tapol), which contained anthocyanin pigments, as a raw material, fermentation without cooking was done at pH 3.5 and 30°C to produce a novel type of alcoholic beverage designated as aromatic red rice wine. The final ethanol concentration achieved during fermentation was 9.3% by volume. Aromatic red rice wine was rich in a fruity aroma and had a characteristic sour taste by gas chromatographic analysis and organoleptic test. Fermentation without cooking was effective for conservation of the red pigment and aroma components of aromatic red rice. The uncooked ethanol fermentation of aromatic red rice in this work has been proven by experiment to be suitable for economical production of a novel type of rose-wine-like alcoholic beverage.

Rice wine brewing with sprouting rice and barley malt

Abstract Though alcoholic beverages are widely made with barley malt in Western countries, as well as in Asiatic countries today, alcoholic beverages are rarely made with sprouting rice. Rice wines were obtained from cooked nonglutinous rice using sprouting rice and barley malt as saccharifying agents with compressed bakers yeast and Kyokai no. 9 yeast, and a comparative study was conducted of the resulting rice wines. The saccharifying activity of barley malt was higher than that of sprouting rice. The amounts of ethyl alcohol, volatile aromatic components, and reducing sugars in the rice wine made with barley malt were higher than those in the wine made with sprouting rice. The rice wine made with barley malt was faintly brownish in color and had heavy, complicated and vulgar characteristics. By contrast, sprouting rice wine was colorless and had light, simple and refined characteristics in terms of both aroma and taste. Sprouting rice wine made with Kyokai no. 9 yeast contained about 8% ethanol with an acidity of around 4.1. Sprouting rice was found to be applicable as a saccharifying agent for ethanol fermentation, as is barley malt. The quality of the sprouting rice wine was further improved through the use of Kyokai no. 9 yeast.

Production and characteristics of sprouting rice wine

Rice grain (Oryza sativa var. Japonica, Reiho) was soaked in running water overnight and incubated at 25°C for 7–8 d to prepare sprouting rice. A novel and/or ancient alcoholic beverage designated as sprouting rice wine was properly made from various starchy materials using sprouting rice powder as a saccharifying agent. Sprouting rice wine containing 9–15% (v/v) ethanol had a characteristic aroma just like Japanese sake and a rather sour taste as judged by organoleptic testing. The rice wine was colorless or faintly yellow and the acidity was around 5.0. Larger amounts of volatile compounds such as higher alcohols and esters were found to be contained in the rice wine by gas chromatographic analysis. As the starchy materials fed to the initial mash were increased, the amounts of ethanol and dextrin contained in the rice wine also increased, and the quality of the rice wine was improved. Though the origin of ancient Japanese sake is still unclear and the evidence for the production of sprouting rice wine in ancient times is insufficient, the legendary and mysterious alcoholic beverage of antiquity made with sprouting rice was reproduced.