Diacetyl Studies. II. Formation and Prevention of Diacetyl in Beer

Burger, Martin; Glenister, Paul R.; Becker, Kurt

doi:10.1080/00960845.1957.12006517

Cited by 4 publications

(2 citation statements)

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“…Shimwell and Kirkpatrick (26) studied diacetyl formation in beer and concluded that the causative agent was not a member of the genus Pediococcus but was in the genus Streptococcus. More recently, Burger et al (3) reported that yeast cells produced diacetyl as a by-product during fermentation of wort used in beer manufacture. They also claimed that Lacto-bacillus pastorianus, a common bacterial contaminant in beer during the lagering stage, produced diacetyl.…”

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Enzymatic Removal of Diacetyl from Beer

Thompson¹,

Shovers²,

Sandine³

et al. 1970

Applied Microbiology

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Diacetyl removal from beer was studied with whole cells and crude enzyme extracts of yeasts and bacteria. Cells of Streptococcus diacetilactis 18-16 destroyed diacetyl in solutions at a rate almost equal to that achieved by the addition of whole yeast cells. Yeast cells impregnated in a diatomaceous earth filter bed removed all diacetyl from solutions percolated through the bed. Undialyzed crude enzyme extracts from yeast cells removed diacetyl very slowly from beer at its normal pH (4.1); at a pH of 5.0 or higher, rapid diacetyl removal was achieved. Dialyzed crude enzyme extracts from yeast cells were found to destroy diacetyl in a manner quite similar to that of diacetyl reductase from Aerobacter aerogenes, and both the bacterial and the yeast extracts were stimulated significantly by the addition of reduced nicotinamide adenine dinucleotide (NADH). Diacetyl reductase activity of four strains of A. aerogenes was compared; three of the strains produced enzyme with approximately twice the specific activity of the other strain (8724). Gel electrophoresis results indicated that at least three different NADH-oxidizing enzymes were present in crude extracts of diacetyl reductase. Sephadex-gel chromotography separated NADH oxidase from diacetyl reductase. It was also noted that ethyl alcohol concentrations approximately equivalent to those found in beer were quite inhibitory to diacetyl reductase.

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“…2Present address: Del Monte Corporation Research Center, Walnut Creek, Wis. 94598. 3 Present address: Charles Pfizer & Co., Inc., Milwaukee, Wis. 53212.…”

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Enzymatic Removal of Diacetyl from Beer

Thompson¹,

Shovers²,

Sandine³

et al. 1970

Applied Microbiology

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Control of Sulphury Impurities in Beer Aroma

Thorne¹,

Helm²,

Svendsen³

1971

Journal of the Institute of Brewing

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Volatile sulphur compounds, particularly hydrogen sulphide and mercaptans, are normal products of yeast metabolism. Although they tend to be purged out of beer during fermentation and maturation, it is not uncommon for finished beer to retain enough of them—up wards of 0·02 ppm as sulphur—to impair its aroma. The addition of a small amount of copper sulphate to sulphury beer cleanses its aroma by transforming volatile sulphur into non‐volatile copper sulphide and mercaptides, but since a considerable proportion of this added copper is liable to be inactivated by complexing with nitrogenous constituents of the beer, the removal of sulphur may necessitate the addition of so much copper as to threaten the shelf life of the beer. It has been found that not only may traces of copper be dosed electrolytically into beer with great precision but that the copper so dosed reacts nearly quantitatively with the volatile sulphur present, thus abolishing the latter with no appreciable increase in the net copper content of the beer. The process has given satisfactory results on an industrial scale, improving the flavour of beers without prejudice to their other characteristics.

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Diacetyl-a Review: Part I-Analytical and Biochemical Considerations: Part Ii-Brewing Experience

Wainwright¹

1973

Journal of the Institute of Brewing

116

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Diacetyl and 2,3-pentanedione are normal products of yeast metabolism and are formed in every brewery fermentation.The desired level in the final beer depends on the particular flavour aimed for but, in all types of beer, flavour defects are caused by excessive concentrations of diacetyl and many brewers might be happy to have no diacetyl in the beer.Recent improvements in analytical techniques show that many of the problems associated with diacetyl are due to the occurrence of compounds which can give rise to diacetyl in the finished beer. These compounds include the so-called "precursor," acetolactic acid, but possibly other compounds such as the bisulphite addition com pound of diacetyl are also involved.Study of the factors affecting diacetyl formation and removal by yeast shows how the concentration of diacetyl in beer can be controlled, and the processes at present used to regulate the diacetyl concentration in beer are described. The yeast strain used, the condition of the pitching yeast, the wort composition, the detailed management of the fermentation and the treatment of the beer during packaging and storage can all affect the diacetyl content of the beer.

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Diacetyl Studies. II. Formation and Prevention of Diacetyl in Beer

Cited by 4 publications

References 1 publication

Enzymatic Removal of Diacetyl from Beer

Enzymatic Removal of Diacetyl from Beer

Control of Sulphury Impurities in Beer Aroma

Diacetyl-a Review: Part I-Analytical and Biochemical Considerations: Part Ii-Brewing Experience

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