Physico-chemical properties of potato starches
2011
Alvani, Kamran | Qi, Xin | Tester, Richard F. | Snape, Colin E.
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 52.6–66.2mg 100g⁻¹. High performance size-exclusion chromatography (HPSEC) fractionation of isoamylase debranched amylopectin showed that the amylopectin molecules were less branched and consisted of more B1, but less A-chains, than cereal starches. Gelatinisation onset (Tₒ), peak (Tₚ) and conclusion (Tc) temperatures of the native potato starches ranged from 58.7 to 62.5°C, 62.5 to 66.1°C and 68.7 to 72.3°C, respectively, whilst the gelatinisation enthalpies ranged from 15.1 to 18.4Jg⁻¹. The gelatinisation temperatures of the starches increased in common with the amounts of short and intermediate sized amylopectin chains. The ¹³C magic angle spinning nuclear magnetic resonance (¹³C 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 (20.6–30.9μm mean diameter). Overall, these data reveal the subtleties of cultivar specific variation against a background of constant environmental conditions.
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