Studies on ATP, ADP, and AMP Concentrations in Yeast and Beer

Abstract

The bioluminescence adenosine triphosphate (ATP) assay has been used to study the yeast and medium ATP content and changes thereof during growth of 36 different ale, lager, and miscellaneous yeasts at 12°, 18°, and 23° C on brewery wort. Significant species-to-species differences were noted for these variables and for the influence of temperature on them. The contrasting patterns of changes in medium ATP levels for ale and lager yeasts, particularly at the lower temperatures, have been suggested as a means of yeast classification and differentiation. Adenosine diphosphate (ADP) and adenosine monophosphate (AMP) assays, based on the stepwise enzymatic conversion of these compounds to ATP and subsequent assay of the ATP by the aforementioned method have been developed. These assays were used to survey the adenine nucleotide concentrations in Canadian beers. Ale ATP, ADP, and AMP levels were generally much higher and covered a wider range than those for lagers. AMP levels in all types of beer examined were more than ten times higher than the ADP or ATP levels. These assays were also used to monitor yeast and medium adenine nucleotide concentrations during several brewery and laboratory fermentations. Significant increases in medium adenine nucleotide levels were observed in the early stages of ale fermentations, followed by gradual decreases in the latter period. The above data were used to derive yeast energy charge (EC) in terms of the ratio of adenine nucleotides. The EC values at various stages of yeast metabolism and fermentation are used to propose several potential practical applications of EC determinations in brewing research and development.