Effects Of Pulse Mode High Pressure Processing On Sterilization And Qualities Of Food During Storage

In this paper, the effects of pulse mode high pressure processing on sterilization of E. coli (ATCC 25922) in carrot juice and qualities of carrot juice during storage was investegated. Enumeration was carried out in brain-heart infusion agar (BHIA) and violet-red bile agar (VRBA) to differentiate between surviving cells with and without injury. Pulse mode high pressure destruct kinetics were evaluated. The shelf life of carrot juice was evaluated at different temperature by detecting different index such as color and pH. This paper also investigated the effects of high pressure processing on sterilization and qualities of salted vegetables. The main results are as follows:1. Pulse mode high pressure treatment has strong effects of injuring E. coli.2. Pulse mode high pressure treatment has strong effects of killing E. coli and higher pressure or more pulse makes better effects.3. A linear model was build up between logND (ND was defined as the number of pressure pulses required for achieving one decimal reduction in microbial population) and pressure:logND=-0.00435P+1.78, R2=0.952, ZP=230MPa.4.°Brix in untreated, HPP-treated and pasteurized carrot juice fell off slightly during storage, but°Brix in HPP-treated and pasteurized carrot juice is little more stable. The pH values of untreated, HPP-treated and pasteurized carrot juice decreased gradually but the pH values of HPP-treated and pasteurized carrot juice decreased more slowly. Both the HPP treatment and pasteurization can extend the shelf life of carrot juice.5. L values in HPP-treated carrot juice is larger than in pasteurized carrot juice. Compared to pasteurized carrot juice, HPP-treated carrot juice generated less precipitation during storage period. HPP treatment does better in maining the quality of carrot juice during storage period.6.600MPa 5min treatment or 600MPa 2pulses can replace the pasteurization to make sure the safety of salted radish and for salted cucumber 400MPa 5min is enough.7. Compared to the pasteurization, high pressure processing make the salted vegetables keep the original color, flavor and mouthfeel.