Convenient Porridge Development And Mechanism Of Gelatinization Retrogradation

Based on the exploring of quality properties of rice material, the processing of instant rice soup has been studied. The test indicates that:1. The suitable processing condition is as follows: Rice of low amylose content ( <16%=, after washing , is soaked in the mixed solution of 0. 2% sodium triphosphate and 0. 4% glucopyrone at room temperature for Ihr. Then it is leached, cooked for 5 min in 6 times boiled water immediately, followed by cooking at 90癈 for 25 min, during which mixture of sucrose fatty acid ester and monoglycerid must be added to the cooking water. When the gelatinization is over , the rice is leached and soaked with 5 times 0.05% pectinase(w%) solution for 90 min, then washed with cool water(15癈) immediately until the surface of grain is not sticky. After soaking the grain in 70% ethanol solution for 5 sec. and drying it by microwave oven (450W, 25min), we get the instant rice soup .which possesses good remoistening property and has no rigid core, with insipid and refreshing taste similar to the common rice soup. The test of quality of the product by TA proves that the above process is reasonable and feasible.The quality of the product can be markedly improved by being modified with addition of 0. 2% (on the basis of total weight) rice essence, 0. 05% mix of CMC and agar(2:l), and 5~10% potato starch.2. The difference of the methods for soaking, enzyme treating and drying affects directly the internal structure of the instant rice soup product, which has great effect on even water-adsorbing, remoistening rate and the occurance of retrogradation that influence such quality index as mouthfeel and quality of instant rice soup.The results from SEM observation can provide theoretical supports for pratical study.3. The occurance of retrogradation is due to the self - organizing phenomenon of starch molecules and resulting in crystal formation during storage of gelatinized starch, which causes the reduction of viscosity and transparency, droping of the molecular flexibitity, coagulating ofsolution and phase-seperating or increasing of the hardness of the precipated gel. Analysis of different rice material hy dynamic rheometer, DSC and TA indicates that: the northeast japonica rice is suitable for instant rice soup making; starch retrogradation is proportional to the time and slight retrogradation can still take place in the starch product prepared by common gelatinizing processing.The re-crystallization of amylopectin could be Inhibited effectively by enzyme trealment such as beta-amylase.