Pasting Behaviour of Starches from Different Origins in Sodium Hydroxide Solution

Abstract

Starches of potato, wheat, corn and rice were pasted in aqueous sodium hydroxide at room temperature, and the pasting behaviour was examined in relation to the concentration of the alkali. Two types of micellar structures were recognized in starch granules. One of them is the weak micells dissociable by the alkali above a definite critical concentration, and the other is the stable ones which bind amylopectin molecules with each other to hold the granular structure of starches even in the alkaline paste.The nature of the alkaline thin paste of starches is essentially determined by the quantity and the distribution of the stable micells in the starch granules in respect to the turbidity, swelling capacity and viscosity through the properties of the swollen granules of the starches. However, the weak micells are considered to be merely a factor affecting the critical concentration of the alkali for the pasting.