ABSTRACT
High hydrostatic pressure is an alternative to thermal processing to inactivate spoilage and pathogenic microorganisms. Cashew apple juice has a pleasant flavor and is rich in vitamin C. Studies to determine the effect of high pressure on microorganisms in cashew apple juice are still lacking. In this study, the inactivation of natural micropopulation and inoculated Escherichia coli by high pressure was evaluated in fresh cashew apple juice. The microbiological stability of pressure-treated juice was also evaluated. The applied high pressure levels ranged from 250 to 400 MPa for periods of 3 to 7 min. Treatments with 350 MPa for 7 min and 400 MPa for either 3 or 7 min reduced the aerobic mesophilic bacteria count to a level below the detection limit. Pressure treatments were also efficient in inactivating yeast and filamentous fungi. The inoculated E. coli (10(6) CFU/mL) was reduced to below 10 CFU/mL after a pressure treatment of 400 MPa for 3 min. The inactivation of this microorganism followed a 1st-order reaction kinetics. The decimal reduction time (D-value) ranged from 1.21 to 16.43 min, while pressure resistance value (z-value) was 123.46 MPa. Neither natural micropopulation growth nor E. coli repair was observed in postprocessed (400 MPa for 3 min) cashew apple juice kept under refrigerated storage (at 4 degrees C) during 8 wk. The results of this study demonstrated the efficacy of high-pressure treatment for preserving cashew apple juice.
