Carbon stable isotopes of glucose during the degradation of rice by the koji fungus .

Glucose, a key component of traditional Japanese fermented foods, is derived from rice starch via saccharification by hydrolytic enzymes produced by . The C value of glucose reflects that of its rice source. However, the influence of saccharification parameters (glucose concentration, degradation temperature, and reaction time) on glucose C values is unclear.

Quantitative determination of vanillin and its detection threshold in sake.

Vanillin is naturally occurring in various food products, including alcoholic beverages; however, its contribution to the aroma of sake is unclear. In this study, an HPLC-MS/MS quantification method was developed and validated by linearity, precision, and recovery, and it was applied to 115 bottles of highly diversified sake. Furthermore, the odor detection threshold of vanillin in sake was determined.

Supported Noble Metal Catalysts and Adsorbents with Soft Lewis Acid Functions.

Heterogeneous noble metal catalysts exhibit various functions. Although their redox functions have been extensively studied, we focused on their soft Lewis acid functions. Supported Au, Pt, and Pd catalysts electrophilically attack the π-electrons of soft bases such as alkynes, alkenes, and aromatic compounds to perform addition and substitution reactions.

Targeted Mutations Produce Divergent Characteristics in Pedigreed Sake Yeast Strains.

Modification of the genetic background and, in some cases, the introduction of targeted mutations can play a critical role in producing trait characteristics during the breeding of crops, livestock, and microorganisms. However, the question of how similar trait characteristics emerge when the same target mutation is introduced into different genetic backgrounds is unclear. In a previous study, we performed genome editing of , , , and on the standard sake yeast strain Kyokai No.

Identification of 2-furanmethanethiol contributing to roast aroma in honkaku shochu and awamori.

Honkaku shochu and awamori are traditional Japanese spirits. 2-Furanmethanethiol (2FM), a volatile thiol, was identified as a roast aroma compound in honkaku shochu and awamori. The detection threshold of 2FM in 25% (v/v) ethanol water solutions was determined as 1.

Isolation of Aspergillus oryzae mutants producing low levels of 2,4,6-trichloroanisole.

Musty or moldy off-odor in sake severely reduces its quality. Such off-odor is caused by 2,4,6-trichloroanisole (TCA), a compound that is produced by Aspergillus oryzae during sake production by O-methylating the precursor 2,4,6-trichlorophenol (TCP). TCP suppresses the growth of fungi, including A.

Genome Editing to Generate Sake Yeast Strains with Eight Mutations That Confer Excellent Brewing Characteristics.

Sake yeast is mostly diploid, so the introduction of recessive mutations to improve brewing characteristics requires considerable effort. To construct sake yeast with multiple excellent brewing characteristics, we used an evidence-based approach that exploits genome editing technology. Our breeding targeted the , , , and genes.

Mutagenesis, breeding, and characterization of sake yeast strains with low production of dimethyl trisulfide precursor.

Dimethyl trisulfide (DMTS) is one of the main components responsible for hineka, the aroma associated with deteriorated Japanese sake during storage. The molecule 1,2-dihydroxy-5-(methylsulfinyl)pentan-3-one (DMTS-P1) has been previously identified as a major precursor compound of DMTS. Furthermore, it had been suggested that the yeast methionine salvage pathway is involved in the production of DMTS-P1.

Awamori fermentation test and 1-octen-3-ol productivity analysis using fatty acid oxygenase disruptants of Aspergillus luchuensis.

1-Octen-3-ol is a major aroma component of awamori, a traditional distilled liquor produced in Okinawa Prefecture, Japan. As 1-octen-3-ol is thought to affect the sensory properties of awamori, it is important to fully characterize the compound's biosynthetic pathway and control mechanism. We previously reported that the fatty acid oxygenase ppoC (ppo: psi-produced oxygenase) of Aspergillus luchuensis is directly involved in the production of 1-octen-3-ol in rice koji (Kataoka et al.

Characteristic analysis of the fermentation and sporulation properties of the traditional sake yeast strain Hiroshima no.6.

General sake yeasts (e.g., Kyokai no.

Selective adsorption of 1,3-dimethyltrisulfane (DMTS) responsible for aged odour in Japanese sake using supported gold nanoparticles.

Gold (Au) nanoparticles (NPs) supported on SiO (Au/SiO) were prepared by a practical impregnation method and applied as an adsorbent for 1,3-dimethyltrisulfane (DMTS), which is responsible for an unpleasant odour in drinks, especially Japanese sake. Compared with a conventional adsorbent, activated carbon, Au/SiO selectively reduced the DMTS concentration in Japanese sake without decreasing the concentrations of other aromatic components. DFT calculations revealed that the selective adsorption of DMTS occurred through the formation of a stable intermediate.

The potential aroma and flavor compounds in Vitis sp. cv. Koshu and V. vinifera L. cv. Chardonnay under different environmental conditions.

Background: Koshu, a hybrid of Vitis vinifera L. and V. davidii Foex, is the most popular indigenous cultivar for wine production in Japan.

Characteristic features of the unique house sake yeast strain Saccharomyces cerevisiae Km67 used for industrial sake brewing.

For several decades, almost all sake has been brewed with sake yeast Saccharomyces cerevisiae Kyokai no. 7 (K7) group strains. Although the widespread use of these strains has contributed to sake quality improvement, it may have lessened the diversity of sake gustatory properties brought about by house sake yeast (indigenous yeast of sake brewery).

Construction of sake yeast with low production of dimethyl trisulfide precursor by a self-cloning method.

Dimethyl trisulfide (DMTS) is the primary component responsible for "hineka", the stale aroma of Japanese sake. Deletion of the MRI1 or MDE1 gene of sake yeast, encoding 5'-methylthioribose-1-phosphate isomerase and 5'-methylthioribulose-1-phosphate dehydratase, respectively, has been reported to greatly reduce the amount of DMTS precursor (DMTS-P1) in sake and to suppress the formation of DMTS during storage. In this study, we constructed sake yeast strains lacking MRI1 gene function by a self-cloning method.

Identification of 4-mercapto-4-methylpentan-2-one as the characteristic aroma of sake made from low-glutelin rice.

The grassy characteristic aroma perceived in brewed sake made from low-glutelin rice (Oryza sativa L. Mizuhonoka) was examined by gas chromatography-olfactometry and gas chromatography-mass spectrometry. By comparing the odor properties and Kovats retention indices to those of standard compounds, 4-mercapto-4-methylpentan-2-one (4MMP) was found to contribute to the characteristic aroma.

Relationship between medium-chain fatty acid contents and organoleptic properties of Japanese sake.

Medium-chain fatty acids (MCFAs) and ethyl esters are considered to contribute to some organoleptic properties, such as fatty odor and bitterness in Japanese sake. However, the relationships between these compounds and the organoleptic properties of sake remain unclear. Here, we quantified MCFAs and ethyl hexanoate in ginjo sake using gas chromatography with a flame ionization detector (GC-FID).

Gas chromatography/mass spectrometry based component profiling and quality prediction for Japanese sake.

Sake is a Japanese traditional alcoholic beverage, which is produced by simultaneous saccharification and alcohol fermentation of polished and steamed rice by Aspergillus oryzae and Saccharomyces cerevisiae. About 300 compounds have been identified in sake, and the contribution of individual components to the sake flavor has been examined at the same time. However, only a few compounds could explain the characteristics alone and most of the attributes still remain unclear.

Yeast cell lysis enhances dimethyl trisulfide formation in sake.

The present study showed that the lysis of yeast cells and subsequent release of cell contents in sake mash accelerated dimethyl trisulfide (DMTS) formation. Among these, heat unstable and relatively high molecular weight compounds were assumed to be enzymes; thus, enzymatic reactions probably contribute to DMTS formation.

Statistical analysis of sake-preparation conditions and dimethyl trisulfide formation.

Dimethyl trisulfide (DMTS) is known to be responsible for hineka, an off-flavor that develops during storage, in sake. Previous studies have attempted to elucidate the mechanism of DMTS formation during sake storage, but the mechanism underlying DMTS formation remains unclear. In this study, we determined the sake-preparation conditions that affect DMTS formation.

Involvement of methionine salvage pathway genes of Saccharomyces cerevisiae in the production of precursor compounds of dimethyl trisulfide (DMTS).

Dimethyl trisulfide (DMTS) is one of the components responsible for the unpalatable aroma of stale Japanese sake, called "hineka". Recently, a precursor compound of DMTS, 1,2-dihydroxy-5-(methylsulfinyl)pentan-3-one (DMTS-P1), was identified. It was speculated that the yeast methionine salvage pathway (MTA cycle) might participate in the formation of DMTS-P1, because the chemical structure of DMTS-P1 was similar to one of the intermediate compounds of that pathway.

Contribution of 1,2-dihydroxy-5-(methylsulfinyl)pentan-3-one (DMTS-P1) to the formation of dimethyl trisulfide (DMTS) during the storage of Japanese sake.

Dimethyl trisulfide (DMTS) is involved in the unpalatable aroma of stale Japanese sake, called "hineka". Recently, we isolated one of the precursor compounds of DMTS in sake and identified it as 1,2-dihydroxy-5-(methylsulfinyl)pentan-3-one (DMTS-P1), a previously unknown compound. In this work, the contribution of DMTS-P1 to the formation of DMTS was investigated.

Breeding of a low pyruvate-producing sake yeast by isolation of a mutant resistant to ethyl alpha-transcyanocinnamate, an inhibitor of mitochondrial pyruvate transport.

Pyruvate is the key substance controlling the formation of diacetyl, acetaldehyde, and acetate during alcoholic fermentation. Here we report the breeding of a low pyruvate-producing sake yeast by isolation of a mutant resistant to ethyl alpha-transcyanocinnamate, an inhibitor of mitochondrial pyruvate transport. Mitochondrial function was involved in resistance to this substance and in the production of pyruvate by the mutants.

Effects of sulfur dioxide on formation of fishy off-odor and undesirable taste in wine consumed with seafood.

In order to evaluate sensory compatibility of alcoholic beverages with food, beverages and dried squid, namely, "surume", a common Japanese accompaniment, were consumed together. White wine and dried squid pairings had a more undesirable taste and more fishy off-odor than sake and dried squid pairings. The undesirable taste and fishy off-odor appeared to be caused by degradation of unsaturated fatty acids (e.

Screening and identification of precursor compounds of dimethyl trisulfide (DMTS) in Japanese sake.

Dimethyl trisulfide (DMTS) is involved in the unpalatable aroma of stale sake, called "hineka"; however, the mechanism underlying the formation of DMTS during the storage of sake has not been elucidated. This paper investigates the precursors of DMTS in sake. An experiment using [methyl-d(3)]-methionine showed that Strecker degradation of methionine plays a minor role in the formation of DMTS.