Optimization Of Vacuumizing And Cold Processing And Qualities Of Pear Pulp

Pear was poor resistant to storage, easy to dehydration dry and spoilage. The technology of traditional concentrated pear juice was complicated, in addition to the inactivation of enzymes, witch needed to go through 3 steps of pasteurization, leading to excessive heating casuing browning and flavor loss seriously. The shelf life was short and the juice rate was low. The way to solve the problem was oxygen-isolated, cold beating and minimal thermal inputs, Of cause, the fresh pear puree can preserve the original flavor, color and nutrients maximally. This study was to optimize the conditions vacuumizing and cold processing of puree and storage tempreture, providing a theoretical basis for pear puree in actual production and commercial application. The results were:The comprehensive evaluation value was the summary of the normalized and weighted Total Number Of Colonies, the activities of polyphenol oxidase(PPO), peroxidase(POD), pectin methyl esterase(PME), Color and Ascorbic Acid(Vc), which was used to reflect the overall quality of the pear pulp for the first time. The results showed gas type was the key factor for the comprehensive evaluation value the pear puree. The optimum parameter of the vacuumizing and cold processing was:beating at 10? in vacuum and pasteurizating at 90? for 7min with the comprehensive evaluation value of (38.21±1.59)%.The production equipment can not reach the vacuum environment, so the trial production of beating environment was in the air. And the process parameters for fresh pear puree was:cleaning pipeline 5min with hot water in CIP system, washing pear with some hypochlorite, beating with small screen and 7%o Vc, enzyme inactivation at 80? for 3min, pasteurizating at 90? for 5min. CIP cleaning with hot water and hypochlorite can decrease the number of microorganisms in pear pulp significantly, the qualities of enzyme inactivation pear pulp is better.Enzyme inactivation and low temperature storage were beneficial to the preservation of nutrient, color and flavor for pear pulp. It can be known that the flavor loss of pear pulp under storage at 25? was higher than that under storage at 4? by means of PEN, in addition, the flavor loss rate of the pear pulp treated enzyme inactivation was higher than that without enzyme inactivation in the same storage temperature.The shelf life of pear puree treated with enzyme inactivation was higher.The shelf life of non-inactivation enzyme pear puree was 23 days, the shelf life of inactivation enzyme puree was 27 days, extended for 4 days under storage at 25?; And the shelf life of non-inactivation enzyme pear puree was 39 days, the shelf life of inactivation enzyme puree was 46 days, extended for 7 days under storage at 4?.