Abstract: The relation between survivors of microorganisms and processing pressure and holding time in UHP treatment tostrawberry juice was investigated. The microorganisms including natural microflora and yeast and mold and E. coli, were is demandedto check up by National Food Hygienic Standard of China (NFHSC). Selected processing pressure was between normal pressureand 500MPa, with holding time range between 0 and 15min. In this experiment. Results showed that under the environmentaltemperature 29℃, E. coli was very sensitive to pressure, which subjected to UHP treatment at 350 MPa for holding time of3minutes could be completely killed; whereas yeast and mold could stand well to press use higher than the E. Coli, whichcould be all killed subjected to UHP treatment at 350 MPa for holding time of 10min. There were a variety of microorganismsin infected microflora of strawberry juice as some was very pressure-resistant. These were lowered to 30cfu/ml of microflorain strawberry juice, subjected to UHP treatment at 500 MPa for holding time of 15min. The measures could meet the criterionof NFHSC.

Key words:  strawberry juice, ultra high pressure, sterilization, microflora, yeast and mold, E. coli