Comparison of Malts for Nuclease and Nucleobase Potentials¹

1 Presented at the 49th Annual Meeting, Nashville, TN, April 1983.

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Abstract

In evaluating malts as suppliers of nucleic acid precursors, 14 malting barleys and one feed barley were malted and analyzed for conventional malt characteristics. Activities of the enzymes deoxyribonuclease, ribonuclease, phosphomonoesterase, phosphodiesterase, 3′-nucleotidase, 5′-nucleotidase, adenosinase, and uridinase, which are concerned with nucleic-acid degradation, were measured. Levels of nucleic acid nitrogen bases in worts from representative malts were also measured. Activities of all enzymes increased during germination, but response to gibberellic acid varied. Considerable nuclease and related enzyme activity of germinated barley resided in the roots, which normally are discarded after kilning. Most malts that showed good performance with regard to the conventional malt characters had high activity of enzymes that degrade nucleic acids, and these malts provided high levels of nucleic acid precursors for yeast. Several barley varieties had good malting characteritistics but were considered only marginal suppliers of nucleic acid degradation products. The levels of nucleic acid bases in worts reflected the activities of the malt enzymes associated with conversion of nucleic acids to nitrogen bases.

• Brewing
• Malts
• Nucleic-acid precursors
• Yeast nutrition