Studies On Ultra-high Pressure Treatment On Coconut Puree

The coconut meat is the endosperm of the Cocoanuts.Besides protein, carbohydrate, and fat, coconut meat is also rich of vitamins and minerals. In this study, fresh coconut meat was used as raw material. The treatment of ultra-high pressure sterilization process was studied. The physico-chemical and preservation quality of puree which was treated by ultra-high pressure technology also investigated. Finally, shelf life of the puree was also predicted by establishing a kinetic model. The main results were as follows:1. In this study the colony count was used as a judging parameter. Single factor and orthogonal experiments showed that ultra-high pressure sterilization process had a remarkable effect on sterilization coconut puree. During ultra-high pressure sterilization process pressure affect the sterilization most, pressure keeping time affect the sterilization less and pressure keeping temperature had the least effect on sterilization. The optimum parameter for sterilization of coconut juice is at500MPa,30℃for10min. Under this condition the colony count was45CFU/g, which meets the national food sanitation standard.2. Different methods were used for coconut puree sterilization, and the physical and chemical quality was measured after sterilization. Compared with the heating method, ultrahigh pressure sterilization process left coconut puree a better color, smelling and taste. No much difference for PH,the crude protein content and non-enzymatic browning index of coconut puree was observed between heating method and ultrahigh pressure sterilization process. A lower pressure will increase the oxidation of fat, otherwise it will inhibit the oxidation. Ultrahigh pressure sterilization process can keep all the nutrition qualities of fresh coconut flesh.3. Sterilizing raw coconut puree at the condition of500MPa,30℃for10minutes and then it was stored at4℃for16days. Compared with the controlling group, ultra-high pressure sterilization process can sterilize the microorganism efficiently. No significant change on color and smelling of coconut puree was observed during the storage time of16days. PH increased a little bit, and at the same time it was relatively stable. Conductivity and solid content decreased slowly by ultrahigh pressure sterilization process in a certain way. In sum, ultrahigh pressure sterilization process will slow down the deterioration of coconut puree, extend the storage period. It is a very effective way of preservation.The preservation period of coconut puree treated at the condition of500MPa,30℃for10minutes can be up to more than3months.4. With pH used as an indicator to evaluate coconut puree freshness quality, a Kinetic model for predicting the shelf life of coconut puree was established as below:According to the prediction model, when the pressure was295K,305K and315K, the shelf life was8.28d,4.91d and2.87d, respectively.