The objectives of this research were 1) to determine the optimum condition for the production of β-limit dextrin having various average molecular weights from mung bean starch by using α- and β-amylase, 2) to study the chemical and physical properties of the β-limit dextrin and 3) to study the relationship between the flow behavior and average molecular weight of β-limit dextrin. The results showed that the optimum condition of mung bean starch hydrolysis by α- amylase in liquefaction stage was pH of 5.0 and temperature of 90°C and that by β-amylase in saccharification stage was pH of 5.5, temperature of 60°C and the ratio of β-amylase to dry starch of 12.86 KU/100 grams for 48 hours. There conditions were used for β-limit dextrin production. To produce β-limit dextrin, 20 g/dl mung bean starch suspension was liquefied with α- amylase and for 30 minutes using the ratio of α- amylase to dry starch of 3.32, 6.64, 9.96, 13.28 and 16.60 KNU to 100 grams. Then, the liquefied starch was saccharified with β-amylase resulting in dextrin mixture. To obtain β-limit dextrin, the dextrin mixture was dialyzed at molecular weight cut off 12,000. The β-limit dextrin had the number average molecular weight of 277363, 23588, 22645, 17784 and 17738, the dextrose equivalent of 11.50, 11.90, 11.80, 13.90 and 13.40 and the intrinsic viscosity 11.39, 9.70, 8.89, 7.62 and 7.33 ml/g, respectively. The yield of β-limit dextrin was 20-30% on dry basis. At 25°C, the 10 g/dl β-limit dextrin solution was found to be Bingham plastic fluid having the yield stress of 703.28, 316.87, 216.91, 165.77 and 143.59 mPa. And the viscosity index of 6.69, 3.50, 3.41, 2.79 and 2.53 mPa.s for the number average molecular weight of 277363, 23588, 22645, 17783 and 17738, respectively.
