Properties Analysis And Optimization Of Cooking Process Of Zongzi

ZongZi are widely popular with the consumers in the south of the Yangtze River.However, there are some problems of Zongzi with four corners in process including largedifferences in densities, long cooking time, large energy consumption and difficulty ofcontrol and so on. This paper aimed at those above-mentioned problems and explored theoptimized process parameters of cooking and sterilization of ZongZi of certain packagedensities under the laboratory condition. Feasibility of optimized process was verified at theperspective of product qualities and cost. In addition, effects of temperature and particle sizeof glutinous rice on qualities of Zongzi were also studied in this paper to obtain best eatingqualities.1. In order to study the effect of package densities on the cookingcharacteristicsofZongZi,this paper investigated the effect of different package densities onthe cooking of ZongZi and the product quality. Result showed that: in the process ofcooking, the average moisture content of ZongZi with different package densities raisedrapidly at first, then increased gradually, stabilized at last.Ultimate moisture content showeda negative linear correlation with package density. Moisture content of product can becontrolled by changing package density of ZongZi.A linear correlation was also showedbetween cooking time and package density of ZongZi.2. Under the laboratory condition, this paper explored the optimized process ofcooking and sterilization for certain package densities ZongZi and verified feasibility ofoptimized production process at the perspective of product quality and cost. Result showedthat: at the early stage of the processing of pre-cooking, the moisture content of ZongZiincreased rapidly, and thenrose gradually, stabilized at last. After pre-cooking for30min, themoisture content of ZongZi was almost stable and the center temperature of ZongZialmostreached the top. Themoisture content of ZongZi with high temperature after pre-cookingrapidly rose at first, and then increased gradually, stabilized at last after been put into thecold water. After soaking for12min, themoisture content of ZongZi achieved the level ofnormal process cooking for90min.Orthogonal experiment results showed that the order of three factors: the pre-cooking time>soaking time in cold water> sterilizing time. Theoptimized process of cooking and sterilization under the laboratory condition was:pre-cooking for30min, soaking in cold water8min, sterilizing under121℃for35min.Theproduction cycleof the optimized process was shortened significantly (about1h), but thephysicochemical indexes and eating quality were no difference with normal process.Themoisture content of the product with optimized process can be controlled through controlthe soaking time.Finally, we accounted for the cost of theoptimized process. The cost ofoptimized process under the laboratory condition was less than normal process, and wouldsave144.56RMB/ton under the condition of the optimal.3. The cooking kinetic of ZongZi was studied. Results showed that cooking rate ofZongZi accords with the first-order kinetics equation during the cooking process. Threecooking rate constants were observed of all ZongZi with different package densities. Therewere three stages in cooking process of ZongZi. The cooking rate of first and second stageassociated with package density, but the third stage didn’t. What’s more, the fact that therewere three cooking rate constants of normal process as against four of optimized processemphasized the benefits of soaking ZongZi in cold water before cooking.4. This paper investigated the effect of different temperatures and particle sizes ofglutinous rice on texture and sensory qualities of ZongZi. Cooking quality of lard in ZongZiwas also studied. Results showed that temperature had a significant effect on texturequalities of ZongZi. As the temperature raised, hardness of ZongZi decreased. Similarly,temperature had a significant effect on the sensory qualities of ZongZi. When temperaturewas37℃, ZongZi would get the best sensory qualities of good appearance and taste.Meanwhile, particle size of glutinous rice had a great effect on quality and structurecharacteristics of ZongZi. The particle size of glutinous rice showed an obvious linearcorrelation with texture indexes of ZongZi. With the decrease of the particle size ofglutinous rice, hardness, adhesiveness and chewiness of ZongZi increased, but adhesivenessand springiness fell. The smaller the particle size of glutinous rice was, the higher thehardness was. In addition, the relationship between hardness and C value of the lard in ZongZi followed the following formula (x-C value, y-hardness, g): y=5139e-0.01x (R~2=0.992).