Effects of Salts on Mechanical Properties of Heated Rice Grains

Abstract

The effects of sodium ion and calcium ion on hardness of rice grains such as Koshihikari, Yukinosei and Akihikari, were investigated using breaking stress and weight uptake measurements, and inner structures of the samples were observed via scanning electron micrographs. When the same rice species was heated in the deionized water, sodium chloride aqueous solution and calcium chloride aqueous solution, the magnitude of breaking stress became higher in a order: the deionized water < sodium chloride aqueous solution < calcium chloride aqueous solution. In the same kind salt solution, the magnitude became higher in a order: Koshihikara < Yukinosei < Akihikari. The value of weight uptake of the same rice grains was larger in a order: calcium chloride aqueous solution < sodium chloride aqueous solution < the deionized water. The circumference structures of rice grains heated in aqueous sodium chloride and calcium chloride solution looked more compact and had finer texture than those heated in the deionized water.