REVERSED-PHASE HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY OF OAT PROTEINS- APPLICATION TO CULTIVAR COMPARISON AND ANALYSIS OF THE EFFECT OF WET-PROCESSING

Oat protein fractions were characterized by reversed-phase high-perfor mance liquid chromatography (RP-HPLC). Salt-soluble, alcohol-soluble, and alkali-soluble protein fractions were extracted with 1.0 M NaCl, 5 2% ethanol, and 1% sodium dodecyl sulfate (SDS) in 0.05 M borate buffe r (pH 10), respectively. RP-HPLC analysis conditions were first optimi zed for column performance, concentration of ion-pairing reagent (trif luoroacetic acid [TFA]), protein reductive state, and elution temperat ure. These analysis conditions were used to characterize five Finnish oat cultivars (Puhti, Ryhti, Veli, Nasta, and Virma). In addition, eff ects of processing on oat protein composition were analyzed in high-pr otein oat flour and steamed oat goats derived from the oat starch proc ess. Wet processing only slightly influenced RP-HPLC separation profil es of protein fractions. The greatest difference between high-protein oat flour and groats was the amount of salt-soluble components eluting during the first 15 min. Prolamin patterns of Puhti, Ryhti, and Virma clearly differentiate these cultivars. Prolamin patterns of cultivars Veli and Nasta were similar; half the genome in these cultivars is fr om the same parent. For all cultivars, RP-HPLC separations of salt- an d alkali-soluble proteins were similar. However, quantities of some co mponents differed, particularly those in the alkali-soluble fraction. RP-HPLC reproducibility was generally good, although replicate alcohol extractions revealed some components not consistently present. These were probably due to the extractant (52% ethanol). Other trials sugges ted that 70% ethanol may be a more reliable oat prolamin extractant fo r RP-HPLC analysis. These results emphasize the importance of thorough ly optimizing RP-HPLC analysis conditions for protein characterization .