GELATINIZATION AND SOLUBILITY PROPERTIES OF COMMERCIAL OAT STARCH

Gelatinization and solubility characteristics of starch contribute to unique functionality in foods. Corn and oat starch viscoamylographs (3 5g db) showed peak viscosities of 400 and 390B.U., respectively. Oat s tarch had a more rapid (89.7 vs 85.6 degrees C) and higher set back (7 90 vs. 740B.U.) than corn. Data on soluble components of cooled (85 de grees C) starch pastes, as collected and analyzed by high-performance size exclusion chromatography (HPSEC), suggest that amylopectin plays a significant (P<0.05) role in oat paste set back; for corn starch, am ylose is the dominant factor. Solubilities and apparent molecular weig hts (MW) of oat starch heated (65-120 degrees C) under shear and subse quent sonication (0-40s) in water or 90% methyl sulfoxide (DMSO) were also determined by HPSEC. An intermediate MW fraction was eluted on th e HPSEC chromatograms only when oat starch was heated in water (100-12 0 degrees C/30min) or DMSO and sonicated, suggesting that this fractio n may not be inherent in the native granule, in water, polymer solubil ity and peak MW increased with temperature (65-120 degrees C), whereas in DMSO, solubility decreased with heating (65-100 degrees C), while peak MW remained basically constant. Aqueous tag) leaching at 75 degre es C solubilized more corn amylose than amylopectin, but amylopectin a nd amylose co-leached from oat starch granules. Aq leaching, at 20 deg rees C above their DSC peak ends (85 and 95 degrees C for oat and corn , resepctively), showed more amylopectin leached from oat starch granu les whereas more amylose was leached from corn starch granules.