Physico-chemical properties of potato starches

Starches were isolated and characterised from 10 potato cultivars grown under the same conditions (with a commercial starch for reference). The chemical composition revealed some differences amongst the starches with protein ranging from 0.30% to 0.34%, amylose 25.2% to 29.1% and phosphorus 52.6-66.2 mg 100 g(-1). High performance size-exclusion chromatography (HPSEC) fractionation of isoamylase debranched amylopectin showed that the amylopectin molecules were less branched and consisted of more 81, but less A-chains, than cereal starches. Gelatinisation onset (T-o), peak (T-p) and conclusion (T-c) temperatures of the native potato starches ranged from 58.7 to 62.5 degrees C, 62.5 to 66.1 degrees C and 68.7 to 72.3 degrees C, respectively, whilst the gelatinisation enthalpies ranged from 15.1 to 18.4J g(-1). The gelatinisation temperatures of the starches increased in common with the amounts of short and intermediate sized amylopectin chains. The C-13 magic angle spinning nuclear magnetic resonance (C-13 CP-MAS NMR) and wide angle X-ray diffraction (XRD) data (30.6%+/- 0.22% crystallinity on average) showed little variance amongst the samples. Particle sizing results, however, revealed more variance (20.6-30.9 mu m mean diameter). Overall, these data reveal the subtleties of cultivar specific variation against a background of constant environmental conditions. (C) 2010 Elsevier Ltd. All rights reserved.