VIEW ARTICLE    DOI: 10.1094/ASBCJ-53-0045

Activity of Lipoxygenase Isoenzymes During Malting and Mashing (1,2). Guoshen Yang and Paul B. Schwarz, Department of Cereal Science, North Dakota State University, Fargo, ND. (1) Presented in part at the 59th annual meeting, Tucson, AZ, June 1993. (2) Published with the approval of the Director of the Agricultural Experiment Station, North Dakota State University, Fargo, ND as Journal Series 2230. J. Am. Soc. Brew. Chem. 53(2):45-49, 1995. Accepted August 29, 1994.

The objective of this study was to evaluate the development and stability of the lipoxygenase (LOX) isoenzymes LOX-1 and LOX-2 during malting and mashing. LOX-2 was detected only in germinating barley, while LOX-1 was present in sound grain. The activity of both isoenzymes increased during germination. Total LOX activity, and the ratio of LOX-1 to LOX-2, varied among the three samples used in this study. LOX-1 and LOX-2 activities decreased at similar rates during kilning, and only 1-3% of the total LOX developed remained in the micromalts. The remaining activity was primarily LOX-1. The two commercial malts tested contained higher LOX activities. During mashing, about one third of the total LOX was extracted into the wort. The majority of the activity remained in the grist and was more thermostable than that in the wort. LOX activity was also affected by germination temperature. The addition of gibberellic acid (GA(3)) and abscisic acid (ABA) was determined to have no significant effect on LOX activity. Keywords: Barley, Isoenzyme, Kilning, Lipoxygenase, Malting, Mashing