Multifunctional-separation-mode ion chromatography method for determining major metabolites during multiple parallel fermentation of rice wine.

Facile and effective analysis methods are desirable for elucidating the behaviours of metabolites during fermentation reactions. Herein, a multifunctional-separation-mode ion chromatography (MFS-IC) method was developed for the simultaneous monitoring of major metabolites during multiple parallel fermentation, including those related to central carbon metabolism (saccharification, glycolysis, alcoholic fermentation, and the tricarboxylic acid (TCA) cycle). The use of two types of sulfo-modified size-exclusion columns and phthalic acid as the eluent allowed the separation of oligosaccharides (disaccharides, trisaccharides, and tetrasaccharides), glucose, pyruvate, and major organic acids during the TCA cycle (-aconitate, citrate, -citrate, malate, fumarate, and succinate but not α-ketoglutarate) from other non-target analytes.

Reduction of the alcohol-stimulative taste of Japanese pot-distilled spirits.

The Japanese traditional pot-distilled spirit shochu has various tastes that are produced by variations in the manufacturing processes. In this study, an alcohol-stimulative taste was organoleptically evaluated using shochu samples, and the chemical components and proton nuclear magnetic resonance (H NMR) spectra were measured. In some shochu samples, the alcohol-stimulative taste was weaker than that of the standard 15% (v/v) EtOH-HO mixture, and the water-ethanol hydrogen-bonding structure was stronger compared to a water-ethanol solution.

Effects of solutes on the alcohol-stimulative taste of vodkas.

Quantitative analyses of chemical components and sensory tests were carried out on vodka samples to test for stimulative taste of ethanol. Proton nuclear magnetic resonance (H NMR) spectra of the vodkas were measured with 600 MHz NMR. The effects of salts on the alcohol-stimulative taste were investigated for 15% (v/v) EtOH-HO solution.

Hydrogen bonding of water-ethanol in alcoholic beverages.

An alcoholic beverage is a type of water-ethanol solution with flavor and taste. The properties of the hydrogen bonding of water-ethanol in alcoholic beverages have not been clarified sufficiently. We investigated factors that could affect the hydrogen-bonding structure of water-ethanol on the basis of proton nuclear magnetic resonance (1H NMR) chemical shifts of the OH of water-ethanol and Raman OH stretching spectra.

Proton nuclear magnetic resonance and Raman spectroscopic studies of Japanese sake, an alcoholic beverage.

The hydrogen-bonding property of water--ethanol in Japanese sake, a kind of brewage, was examined on the basis of both (1)H NMR chemical shifts of the OH of water--ethanol and the Raman OH stretching spectra. In 20% (v/v) EtOH-H(2)O solution, amino acids as well as organic acids caused low-field chemical shifts, i.e.

Hydrogen bonding in alcoholic beverages (distilled spirits) and water-ethanol mixtures.

The hydrogen-bonding properties of water-ethanol of alcoholic beverages and water-ethanol mixtures of the corresponding ethanol contents were examined on the basis of OH proton NMR chemical shifts and the Raman OH stretching spectra of water and ethanol. Japanese shochu, an unaged distilled spirit of 25% (v/v) alcoholic content made from various grains, was provided for the samples; it is a high-purity spirit as it contains only small amounts of dissolved components, like typical vodka, gin, and white rum. The hydrogen-bonding structure in shochu containing some acids was found to be different from that of the water-ethanol mixture with corresponding ethanol content.

Solute effects on the interaction between water and ethanol in aged whiskey.

The hydrogen-bonding structure of water-ethanol in whiskey was examined on the basis of (1)H NMR chemical shifts of the OH of water and ethanol. Phenolic acids and aldehydes (gallic, vanillic, and syringic acids; vanillin and syringaldehyde) exhibited their structure-making effects regardless of the presence or absence of 0.1 or 0.