EFFECT OF THE ANTIOXIDANT 2''-O-GLYCOSYLISOVITEXIN FROM YOUNG GREEN BARLEY LEAVES ON ACETALDEHYDE FORMATION IN BEER STORED AT 50-DEGREES-C FOR 90 DAYS

Beer samples were stored at 50 degrees C for 90 days, and the amount o f acetaldehyde in the samples was measured periodically by gas chromat ography. Acetaldehyde in the beer sample was derivatized to 2-methylth iazolidine with cysteamine and quantitatively analyzed with a gas chro matograph equipped with a fused silica capillary column and a nitrogen -phosphorus detector. All beer samples contained acetaldehyde ranging from 30 to 80 mu M before storage. The concentration of acetaldehyde i n beer samples increased by 873% after 90 days of storage. Significant formation of off-flavor was observed in these samples. When a beer sa mple was stored at 50 degrees C for 10 days with 1 1 mu g/mL of 2 ''-O -glycosylisovitexin and butylated hydroxytoluene, the acetaldehyde con tent was reduced by 60 and 15%, respectively. On the other hand, addit ion of 1 mu g/mL of alpha-tocopherol increased the acetaldehyde conten t by 18%.