Two 2,3-butanediol dehydrogenases (enzymes 1 and 2; molecular weight of each, 170,000) have been partially purified from Lactococcus lactis subsp. lactis (Streptococcus diacetylactis) D10 and shown to have reductase activity with either diacetyl or acetoin as the substrate. However, the reductase activity with 10 mM diacetyl was far greater for both enzymes (7.0- and 4.7-fold for enzymes 1 and ...

In the title mol-ecule, C(14)H(15)N(3)O(4)S, the pyrazole ring is aligned at a dihedral angle of 55.5 (1)° with respect to the benzene ring; the mean planes of the acetyl substituents are twisted by 13.4 (3) and 30.1 (3)° with respect to the pyrazole ring. Inter-molecular classical N-H⋯O and weak C-H⋯O hydrogen bonding links the mol-ecules, forming a three-dimensional network architecture in th...

Diacetyl (2,3-butanedione) imparts an unpleasant "butterscotch-like" flavor to alcoholic beverages such as beer, and therefore its concentration needs to be reduced below the sensory threshold before packaging. We examined the mechanisms that lead to highly elevated diacetyl formation in petite mutants of Saccharomyces cerevisiae during beer fermentations. We present evidence that elevated diac...

In this study, Candida glabrata, an efficient pyruvate-producing strain, was metabolically engineered for the production of the food ingredient diacetyl. A diacetyl biosynthetic pathway was reconstructed based on genetic modifications and medium optimization. The former included (i) channeling carbon flux into the diacetyl biosynthetic pathway by amplification of acetolactate synthase, (ii) eli...

Obstructive lung diseases including bronchiolitis obliterans have been reported among microwave popcorn production employees. Butter flavourings including diacetyl have been associated with these findings. The present study was initiated at four microwave popcorn production plants to determine if exposure to diacetyl was associated with decrements in pulmonary function. Comprehensive diacetyl e...

In the over-all reaction, one molecule of diacetyl is oxidized to two molecules of acetate, and another molecule of diacetyl is reduced to acetoin. The reaction was shown to require cocarboxylase (DPT).2 Subsequently, Schweet et al. (1951) expanded this finding and pointed out the similarity between the diacetyl reaction and pyruvic acid oxidation, with respect to the metabolism of the "active ...

During malolactic fermentation in wine by Oenococcus oeni, the degradation of citric acid was delayed compared to the degradation of malic acid. The maximum concentration of diacetyl, an intermediary compound in the citric acid metabolism with a buttery or nutty flavor, coincided with the exhaustion of malic acid in the wine. The maximum concentration of diacetyl obtained during malolactic ferm...

Occupational exposure to butter flavoring vapors (BFV) is associated with significant pulmonary injury. The goal of the current study was to characterize inhalation dosimetric patterns of diacetyl and butyric acid, two components of BFV, and to develop a hybrid computational fluid dynamic-physiologically based pharmacokinetic model (CFD-PBPK) to describe these patterns. Uptake of diacetyl and b...

Separate sampling and analytical methods for the determination of diacetyl and acetoin have been developed to assess workplace exposures at a popcorn processing facility have been described. Diacetyl (NMAM 2557) is efficiently recovered from an Anasorb CMS sampler tube when the composition of methanol in the desorption solvent is 1%, and acetoin (NMAM 2558) is efficiently recovered when the con...

The dissociation of diacetyl dilute in krypton has been studied in a shock tube using laser schlieren densitometry, LS, at 1200-1800 K and at two reaction pressures, 55±2 Torr and 120±3 Torr. The experimentally determined rate coefficients show falloff. An ab-initio/Master Equation/VRC-TST analysis was used to determine pressure dependent rate coefficient expressions that are in good agreement ...