Effect of starch gelatinization on textural properties of purple waxy rice

Abstract

The present research aimed to investigate the effect of grain starch gelatinization during drying process of paddy rice by fluidized bed system on textural property of the cooked purple waxy rice. The test was initiated by rewetting purple waxy paddy to gain the harvested moisture content of 28.3 and 33.3% (d.b.). The paddy was dried in a fluidized bed dryer at the temperatures of 100, 130 and 150°c until the paddy moisture content was reduced to 22.0% (d.b.). The dried paddy was then ventilated under ambience temperature until the moisture was reduced to 13.0-15.0% (d.b.). It was found that the level of increased gelatinization had a direct relation with the initial moisture of the paddy and drying temperature. The increase in gelatinization of dried paddy lead to the increase of stickiness in contrast to the decrease of hardness in the cooked rice. As a result, drying paddy under different temperatures by fluidized bed system could be used to improve the textural properties of cooked purple waxy rice. To produce cooked purple wazy rice with more tender and sticky texture, the harvested paddy shoude be dried with the drying temperature of 150°c.