Varietal and Annual Variations in Pasting Properties of Sweet Potato Starch.

Abstract

To analyze the varietal and annual variations in starch pasting properties in sweet potato storage roots, twenty cultivars and strains were grown in both 1996 and 1997. The starch pasting properties were investigated using a Rapid Visco-Analyzer (RVA), and the amylose content and starch content were also examined. The pasting properties showed wide ranges of variation among cultivars and strains, and the amylose content ranged between 13.3 and 17.2%. The correlation coefficients of the pasting temperature, peak viscosity, setback, amylose content and starch content between the two years were 0.867***, 0.654**, 0.784***, 0.902*** and 0.864*** respectively. Analysis of variance showed that the varietal differences were significant at 0.1% Ievel for the pasting temperature, setback, amylose content and starch content. The differences among strains and years were significant at 1% Ievel for the pasting temperature, peak viscosity and breakdown. The estimated heritability values of the pasting temperature, peak viscosity, setback, amylose content and starch content were 0.80, 0.49, 0.77, 0.88 and 0.85, respectively. The amylose content showed significant positive correlations in both years with the pasting temperature, the peak viscosity temperature and the setback. The starch content did not show any significant correlatioui with the pasting properties and the amylose content. These results indicate that it is possible to breed for the improvement of the starch pasting properties in sweet potato.