The Study On The Conductivity Of Rice Cooking Characteristics

Rice is our country’s main food crops,65%of our population take rice as staple food. When consuming cooked rice people will generally focus on the taste, visual effects and softness, so people call this taste from sense. In general, rice quality is the main factor that effects the taste of cooked rice, and the process of cooking is also an important factor. With the improvement of living standards, people demands higher taste quality of cooked rice. And as the technology evolves, we have more measurements for rice in different periods. At present, the research for cooking process is mainly concentrated in the cooking process optimization and the correlation analysis between rice physical properties and taste quality of rice, but the transformation of rice soup in the cooking process is rarely involved. In this paper, the electrical conductivity of rice water and particle size change both in cooking and after the end of the cooking process are analyzed. We aslo explore the feasibility of its application in the evaluation of the palatability.1. Soaking the rice for30minutes before the cooking can significantly affect the conductivity of rice water. Soaking the rice for30minutes before the cooking promots the rice the quality of water-swelling, increases the time the rice in the rice water. It makes the endogenousenzyme of raw rice keep activity in the low-temperature cooking process much longer and increase the degree of the macromolecules’ shydroly sis, and at the same time, increases the electrolyte concentration in the soluble rice water. In the cooking process, the degree of gelatinization is much higher in the rice soaked for30minutes than which is not. The same situation occurs to conductivity, iodine-blue value and the transmittance.2. With the extension of cooking time, the rice water’s conductivity value increases. During cooking, the grains swell, the out-layer starches of rice grain gelatinize earlier than inner-layer, the surface occurs cracks, and the internal part occurs voids. When the braising stage is over, water and solid fill up the cracks on the surface; the amylose, soluble solids and concentration of electrolyte dissolved in rice water are increased.3. Conductivity of rice water has significant negative correlation with springiness, cohesiveness, chewiness, resilience of cooked rice. At the same time conductivity of rice water can be effected by crude protein, crude fat and ash in rice. This shows that rice water conductivity can measure taste quality of cooked rice of different varieties. 4. In ordinary pressure cooking modes, rice water’s conductivity reflect o water amount. Put different water before atmospheric cooking, the conductivity of rice water has significant negative correlation with hardness, adhesiveness, gumminess, chewiness of cooked rice.5. In high pressure cooking modes, rice water’s conductivity reflect to water amount. Changes in the conductivity of the rice water after cooking can’t reflect the changes in the cooking quality of the rice when in the condition of autoclaved cooking and different ratioes of the rice and water. That may be due to in the case of different ratioes of the rice and water, evaporation makes the pot pressure maitain the time in consistency, while the distribution of electrolyte and particle sizes solubled in rice water are unstable.6.Rice water’s conductivity and iodine-blue value exists between the significant correlation, and suggest that in the higher after cooking conductivity, rice water dissolution of the higher concentration of electrolyte, rice soaks raises liquid dissolution of the soluble amylose content is higher, the grain that outer structure more loose.