VIEW ARTICLE    DOI: 10.1094/ASBCJ-42-0047

Lipoxygenase and Hydroperoxide Isomerase Activity of Malting Barley. P. B. Schwarz and R. E. Pyler, Department of Cereal Chemistry and Technology, North Dakota State University, Fargo 58105. J. Am. Soc. Brew. Chem. 42:0047, 1984.

The lipoxygenase and hydroperoxide isomerase activities of 10 malting barley varieties and advanced breeding lines were measured in mature barley and in corresponding malts. Significant variability in the lipoxygenase and hydroperoxide isomerase activities of barley was due to variety and growth location. The levels of both enzymes increased markedly over a five-day germination period. Exogenous gibberellic acid did not affect the level of activity in three-day green malts. The level of lipoxygenase activity in five-day green malt was significantly affected by variety, but poor correlations were found between levels in barley and malt. Hydroperoxide isomerase activity in five-day green malts was not significantly affected by any of the factors studied. Lipoxygenase activity was largely destroyed by kilning, but hydroperoxide isomerase was not greatly affected. Hydroperoxide isomerase extracts were moderately heat stable, but this activity was not extractable under mashing conditions. A small amount of lipoxygenase was extracted and was active during the initial stages of mashing, but this activity disappeared when the mash temperature reached 70° C.

Keywords: Barley, Hydroperoxide isomerase, Lipoxygenase, Malt