Changes in the Level of Endogenous Abscisic Acid in Barley During Germination and Use of Abscisic Acid in Malting. K. Yamada, Kirin Brewery Co., Ltd., Brewing Science Laboratory, Miyahara, Takasaki, Gunma, 370-12, Japan. J. Am. Soc. Brew. Chem. 42:0079, 1984.

Changes in the level of endogenous abscisic acid (ABA) in barley during malting were studied. On the basis of the results obtained, a new malting technique with ABA and gibberellic acid (GA₃) was developed. Barley was extracted with acetone, and the ethyl acetate-soluble acidic fraction obtained from the acetone extract was subjected to Sephadex LH-20 column chromatography, silicic-acid partition column chromatography, the silica gel thin-layer chromatography. The fraction corresponding to ABA was collected and methylated. ABA was measured in a gas chromatograph equipped with an electron capture detector. Malting and brewing were performed in a pilot plant. Endogenous ABA was found in barley. Its level decreased greatly during steeping and then gradually increased during germination. On the basis of these observations, we studied the effects on malt quality of ABA and GA3 added to barley during malting. With appropriate combinations of ABA and GA₃, high yields of a malt with a high extract, high diastatic power, moderate wort color, and good fermentability was obtained. Normal beer was resulted from the brewing of such malt.

Keywords: Abscisic acid, Barley, Bromate, Germination, Gibberellin, Malting