Processing Technology And Quality Evaluation Of Instant Rice For Room Temperature Storage

The instant rice present have disadvantages of high circulation cost and poor quality,which limited the further development of instant rice.In order to solve the problems of instantrice mentioned above, a new kind of instant rice was prepared, which have good ediblequality and can be stored at room temperature. The processing was as follows: the raw ricewas elutriated and soaked. After mixed with palm oil and other ingredients, the rice wascooked and then was vacuum packed with dishes and sterilizated.The quality evaluation method of instant rice for room temperature was established usingmethods of sensory and texture analysis. It was found that the hardness and adhesiveness oftexture have significant relativity with sensory quality, which can be used as main parametersof the texture analysis of instant rice. Compared with sensory assess, it was found that sampletasted delicious when hardness value was between350and390, was under300g,adhesiveness was between2.7and3.2.The processing of instant rice for room temperature was investigated in this study.Hardness, adhesiveness and sensory score were used as targets. The optimized soakingprocessing conditions were soaking time60min, and soaking temperature25oC and the1:1.4ratio of water-to-rice. The edible quality of instant rice was improved with addition of8%（w/w） palm oil. The best quality was obtained with1:1.1ratio of water-to-rice and30mincooking time. X-ray diffraction results showed that palm oil changed the A-type crystal of therice starch into VII-type crystal Furthermore, comparing the controls with and test groupsstorage for21days under the condition of4oC, the addition of8%（w/w） palm oil reduced theretrogradation enthalpy change of instant rice from7.4J g^-1to5.1J g^-1.The effect of storage at room temperature （25±1oC） for180days on the quality of instantrice for room temperature was studied. The hardness and retrogradation enthalpy valueincreased, while the adhesiveness decreased. The hardness and adhesiveness andretrogradation enthalpy value during storage had a significant relevance. Good flavorcompounds of instant rice decreased gradually. Among that, esters decreased by30%. Whilebad flavor such as aldehydes increased by8%. The results indicated that addtion ofantioxidant TBHQ into the palm oil increased the oxidation resistance significantly and oilrancidity did not occurred within180days. During storage at room temperature, the colordifference was not significant.Instant rice for room temperature in this study was compared with the commercialsimilar products. The results showed that the instant rice obtained in this study had a goodacceptability.