Publication : National Conference
Preheat Treatment, Enzyme-Substrate Ratio and Hydrolysis Time Affecting on Dextrose Equivalent and Viscosity of Sinlek Brown Rice
AbstractSinlek is nutritious rice and contains high amount of iron. An approach to increase a valuable product of Sinlek rice is to use as an ingredient for beverage powder. However, with its viscosity, it cannot be prepared at high concentration. The way to solve this problem is to hydrolyze the starch to reduce the viscosity. In this research, the main objective is to investigate preheat treatment, enzyme-substrate ratio and hydrolysis time on dextrose equivalent and viscosity of the products. Sinlek brown rice was milled and sieved before hydrolysis. Alphaamylase (Termamyl SC) was introduced to hydrolyze starch in Sinlek rice. Reducing sugar was analyzed in order to calculate the dextrose equivalent (DE). The viscosity of hydrolyzed product was measured by Brookfield Viscometer. The results showed that preheating temperature (90-95ºC) and time (0-15 minutes) of rice flour before adding enzyme did not affect on the DE of the amylase-hydrolyzed products. With increasing in enzyme/substrate ratio (0.04-0.1 %) and hydrolysis time, DE of the products increased. The viscosity of hydrolyzed products (E/S = 0.01- 0.1:100 and hydrolysis time for 90 min.) at a concentration of 20% was in the range of 88-372 cps. From the experiment, it could be concluded that preheat treatment of rice flour at a temperature of 90-95ºC for 0-15 minutes can applied for heating flour before adding alphaamylase with no significant difference on DE. A desirable DE and viscosity of the hydrolysis product could be prepared by adding a specified amount of enzyme at a certain ratio of E/S and hydrolysis time.
AdviserAsst. Prof. Doungjai Thirathumthavorn, Ph.D.

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