Abstract: Objective: Our research focused on the effects of additives on the short-term and long-term retrogradation of sweet potato starch (SPS) in order to provide a theory foundation on improving the quality of its starch noodles.Method:The variety trend of viscosity of a mixture of SPS and additives was assayed during heating and cooling by rapid viscosity analysis (RVA) in order to analyse the properties of gelatinization and short-term retrogradation of the mixture system. Its gel firmness by texture analysis and the To, Tp, Tc, ΔH of the mixture system after crystallization by differential scanning calorimetry (DSC) were also assayed in order to analyse the effect of additives on the property of long-term retrogradation of SPS. Finally the quality of sweet potato starch noodles (SPSN) after being added additives was evaluated. Result:The RVA parameters of sweet potato starch paste and texture quality indexes of its noodles increase with adding additives in a certain extent, especially alum, Artemisia sphaerocephala Krasch (ASK), konjak glucomannan (KGM), and xanthan in terms of the increased extent. The DSC thermogram of retrogradated sweet potato starch with polysaccharide gums shows two peaks. One is melted amylopectin, and another one is an exothermic peak (87～105 ℃), which results from recombination of polysaccharide gums and SPS. Conclusion: The melting temperature of retrogradated SPS increases or decreases with adding polysaccharide gums, but the enthalpy increases. The exothermic peak occurs because polysaccharide gums re-melte and become free at this temperature, compete with a few lipids in SPS, preferentially recombine with amylose in SPS, and then form a firm system. The quality of SPSN added 1% (on the basis of total starch weight) of KGM and ASK (0.95:0.05) is similar to that of mung bean starch noodles and SPSN containing alum.

Key words: additives, polysaccharide gums, sweet potato starch, retrogradation, quality of starch noodles