VARIATION IN OAT GROATS DUE TO VARIETY, STORAGE AND HEAT-TREATMENT .1. PHENOLIC-COMPOUNDS

Low molecular weight phenolic compounds present in heat processed oats (Avena sativa L) were analysed. The oat grains were of three varietie s (Kapp, Mustang and Svea), stored at different relative humidities (3 0, 55 or 80%) and periods (3.5 or 15.5 months) and processed with or w ithout hulls. Eleven UV-absorbing compounds detected by High performan ce Liquid Chromatography were subjected to univariate and multivariate statistical analysis. The selected compounds included caffeic acid, p -coumaric acid, ferulic acid, vanillic acid, p-hydroxybenzaldehyde, va nillin, coniferyl alcohol, three avenanthramides and one unidentified substance. The levels of vanillic acid, vanillin and, especially, p-co umaric acid, p-hydroxybenzaldehyde and coniferyl alcohol increased sig nificantly in samples processed with hulls, but not in samples process ed without hulls. Ferulic acid increased in both processes, while caff eic acid and the avenanthramides were found to decrease during process ing. Storage of unprocessed samples for 1 year generally increased the levels of phenolic acids and aldehydes. For the phenolic acids (excep t ferulic acid), this increase was most pronounced after storage at hi gh relative humidity (80%). The avenanthramides were present at their highest levels in Mustang, caffeic acid in Svea and Mustang, the unide ntified compound in Svea, while all the other compounds studied were p resent predominantly in the variety Kapp. (C) 1996 Academic Press Limi ted