Fragmentation of oat and barley starch granules during heating

The structural differences between oat and barley starches were investigate d by analysing starch polymers released from the granules and the granule r esidues during heating. When the temperature was increased from 85 to 97 de grees C the amount of leached carbohydrates increased from 6.1-8.7% to 36.1 -37.4%. Concurrently, the lysophospholipid content of the granule residues decreased from 0.87-1.0% to 0.35-0.46%, indicating that lysophospholipids w ere also present in the solubilised fraction. Oat and barley starch dispers ions preheated to 95 degrees C were further fractionated by sequential cent rifugation. After the first centrifugation of both starches, 68-70% of the carbohydrate in the supernatant was amylose. After recentrifugation, an ins oluble fraction with a high amylose to lipid ratio was obtained. Oat and ba rley starches showed similar fractionation behaviour, but the molecular wei ght of the solubilised oat starch was somewhat higher. (C) 1999 Academic Pr ess.