Physicochemical and functional proferties of annealing treated sweet potato( Ipomoea batatas) and yam (Discorea species) starches

Abstract

Nowadays, the resistant starch was become more and more popular and known as a healthful carbohydrate, especially in colonic health and glycemic control. Consequ ently, th e purpose of this study was to improve resi stant starch in two kinds of tuber starches including sweet potato and yam starches by u sing annealing method with addin g three different organic acids (aceti d acid, citric acid, lacti c acid). After treatment, th e treated starches were an alyzed to determine the physciochemical properties such as swelling power, solubility, paste clarity, vicosity and resistant s tarch. The swelling power of treated starches was lower than native sweet potato and yam starches while the solubility was higher th an native s tarches ;at the same time th e paste clarity and the viscosity was highly decreased. Espically, the con ten t of resistan t starch (RS) increased significan tly after treament. The RS content in creased from 4.9 ± 0.22 % to 43.6 ± 3.12 % , 41.73 ± 1.35 % ,and 29.56 ± 1.84 % in sweet potato starches with the presence of acetic acid, citric acid, latic acid, respectively. In yam starches, the RS also increased from 7.5 ± 0.81 % to 30.3 ± 2;81 % , 25.2 ± 1.3 %, 27.3 ± 2.86 % with addition of 0.2 M ac eti c acid, citric acic,latic acid, respectively. Because the amount of resi stant starch highly increased, the treated sweet potato and yam starches could be applied in food technology and used as functional food for clinical person related to colonic and diabetic disease. Key words: sweet potato starches, yam starches, resistant starch,annealin g method, organic acids