Composition and properties of starches extracted from tubers of different potato varieties grown under the same environmental conditions

Twelve commercially relevant potato cultivars were grown in a field plot in Perthshire (UK) in 1996. Starches were extracted from these tubers and their physico-chemical properties were investigated with a particular focus on aspects of granule order and corresponding gelatinisation characteristics. There was little variation in (average) granule diameter (21.4±1.6 µm), amylose content (28.7±1.9%) or phosphorus (0.54±0.16 µg mg-1) content. Structural elements of amylopectin were essentially constant in terms of unit distributions and chain lengths (average DP 28±2) with long (F1) and short (F2) chains with average DP of 56±2 and 19±1, respectively. The structures of the (debranched) ß-limit dextrins of the amylopectin molecules were also very similar with the average DP of the two major fractions (F1ß and F2ß) being 48±3 and 37±2, respectively. Peak gelatinisation temperatures (Tp) and enthalpy (¿H) were also correspondingly similar (63.2 °C±1.2 and 18.6 °C±0.8, respectively). The constancy of physico-chemical properties for these starches is in marked contrast to variation in different parameters induced by environmental factors, especially growth temperature.