Varietal and annual variations in pasting properties of sweet potato starch

To analyze the varietal and annual variations in starch pasting properties in sweet potato storage roots, twenty cultivars and strains were grown in b oth 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 amon g cultivars and strains, and the amylose content ranged between 13.3 and 17 .2 %. The correlation coefficients of the pasting temperature, peak viscosi ty, 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 % level for the pasting temperature, setback, amylose content and starch cont ent. The differences among strains and years were significant at 1 % level for the pasting temperature, peak viscosity and breakdown. The estimated he ritability values of the pasting temperature, peak viscosity, setback, amyl ose content and starch content were 0.80, 0.49, 0.77, 0.88 and 0.85, respec tively. The amylose content showed significant positive correlations in bot h years with the pasting temperature, the peak viscosity temperature and th e setback. The starch content did not show any significant correlation with the pasting properties and the amylose content. These results indicate tha t it is possible to breed for the improvement of the starch pasting propert ies in sweet potato.