Experimental Study On Preservation Snap Beans Based On Ice Storage

Snap beans is a specific variety of beans with high quality in the northeast China. As a variety of green vegetable, snap bean is of advantages of nutrition, delicious flavor and health care. But compared with other fruits and vegetables, the snap bean has the features of strong regionalism, seasonality, and decay, so it is difficult for storage, transportation and sales, which results in the contradiction of supply and demand. Therefore, it is urgent to resolve the problem of storage and preservation of snap beans.In North China, the summer is short, while the winter is long and the weather is cold, so there is rich resource of natural cooling. In winter the cooling capacity is stored by the form of ice, and then is released by the the phase change from ice to water in summer. The cooling capacity can be used to preserve fruits and vegetables in summer and autumm. Therefore, it is a good means for protecting environment, saving energy, relieving power shortage and reducing carbon displacement.In this research, the preservation process of snap bean was analyzed. The results suggested that the preservation process was consist of seven stages, which was havesting-grade, pack, precooling, other treatments, transportation, preservation and sale respectively. Comparing with other stages, the precooling was the most important stage. The ice-storage building on snap beans is accordant with the needs. Maple bean was selected as the experimental sample, and the quality index of snap bean and the environment parameters were determined. Cooling load of ice storage building on snap beans was computed. And both of the economic and environmental benefits of snap bean preservation by the ice storage building were analyzed.The model of cold storage of snap bean preservation and the control system of environmental parameters were designed. By LabVIEW software, the automatic control for the temperature, relative humidity and carbondioxide was realized. The content of ethylene was controlled by ethylene detector. According to the automatic control method, the precision and stability of environmental parameters in the ice storage building was improved, and the accuracy of experimental data was ensured.The preservation period of snap bean is researched based on experimental method. The effect of storage temperature, relative humidity and carbondioxide on hardness, brittleness and weight loss rate of snap beans was obtained. The results suggested that the influences of the storage temperature, relative humidity and carbondioxide on hardness, brittleness and weight loss rate were significant, while ethylene content had no effect on every index. The best conditions of preservation were 7~12℃storage temperature, 80%~94% relative humidity and 0.5~3% carbondioxide.A responding surface methodology (RSM) design was employed to optimizate the experimental parameters. The experimental factors were storage temperatures, relative humidity and carbondioxide. According to Design Expert softerware, the regression model of hardness, brittleness and weight loss rate were established, and the effect of each experimental factor and their interactions on hardness, brittleness and carbondioxide were analyzed. The results showed when the optimum processing parameters was 7~10℃of storage temperature, 87~92% of relative humidity and 3% carbondioxide, high hardness and brittleness, and low weight loss rate of snap beans were obtained.