| The sweet potato starch and its modification and application in noodles were studied in this paper.Firstly,moisture adsorption/desorption isotherm were determined and several models(Peleg,Smith,Oswin,Halsey and Henderson model)were used to fit sorption data.The results showed that the Peleg model has comparable excellent performance for fitting of sorption data.When starch samples were stored in an environment which temperature was lower than 30 ? and aw<0.60,its equilibrium moisture content could be kept below 14%and this storage condition was predicted by Peleg model.Then the sweet potato starches were subjected to heat treatment(HMT)and a combination of acid and heat-moisture treatment.Avrami equation was used to model starch retrogradation.The results showed that the solubility,swelling power,light transmittance and the content of rapidly digestible starch(RDS)of sweet potato starch were lower than native starch and decreased with the increase of initial water content during HMT.The content of slowly digestible starch(SDS)and resistant starch(RS)increased.HMT reduced the rate of starch retrogradation.During a combination of acid and heat-moisture treatment,the content of RS of Acid-HMT-4 reached 27.87%,which was higher than that of HMT samples.The light transmittance and apparent amylose content decreased.It was difficult for starch to swell after it was treated by a combination of acid and heat-moisture treatment and gelatinization viscosity of starch was decreased.The potato starch and corn starch had a minimal effect on the estimated glycaemic index(EGI)of the noodles when the supplementation was 10%.HMT-30 and konjac flour could decrease the EGI value of noodles.When noodle contained 10%of HMT-30 and 15%of konjac flour,the sensory quality was good and the EGI value was reduced to 73.29(>55 but<75).This noodle belonged to medium EGI value of food and it can be used as a complementary food for diabetes patients. |
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