Oxalate and Oxalate Oxidase in Malt

Makoto Kanauchi¹, Jérôme Milet² and Charles W. Bamforth^2,3
¹ Department of Food Management, Miyagi University, 2-2-1 Hatatate Taihaku-ku Sendai Miyagi, 982-0215 Japan.
² Department of Food Science & Technology, University of California, Davis, CA 95616-8598, USA.
³ Corresponding author. E-mail:cwbamforth@ucdavis.edu.
A preliminary report of this work was made at the World Brewing Congress, Hawaii, 2008.

Makoto Kanauchi1, Jérôme Milet2 and Charles W. Bamforth2,3 | VIEW ARTICLE

ABSTRACT
Barley kernels contain a single oxalate oxidase located in the embryo and aleurone. It is already present in substantial quantities in unmalted grain and increases in activity during germination. It displays a very broad pH optimum: the optimum was at pH 4.0, but the enzyme still displayed more than 50% of its activity at pH 7. Oxalate oxidase is highly resistant to heat. However, its low affinity for oxygen suggests that it probably does not play a major role in the consumption of oxygen in mashing. The decrease in oxalic acid levels late in germination may be a result of oxalate oxidase action. Oxalic acid was not detected in raw barley.

Key words:
barley, malting, mashing, oxalate oxidase, oxalic acid.