Comparison of static and step-pulsed ultra-high pressure on the microbial stability of fresh cut pineapple

Fresh cut pineapple cubes inoculated with 10(4-5) CFU g-1 Saccharomyces cerevisiae were packed in heat-sealed polyethylene pouches and subjected at ambient temperature to static and step-pulsed ultra-high pressure (UHP) treatments. Static treatments included 100 and 9000 s at 270 MPa and 9000 s at 340 MPa. Step-pulsed pressure treatments included 100, 300 and 600 s at 0-270 MPa using 0.5-s and 10-s pulses. Inoculated treated and untreated samples were held at 4 degrees C for 60 days. Bacteria and yeast counts were determined using plate count agar and yeast extract peptone dextrose agar, respectively. Static treatment at 270 and 340 MPa for 9000 s resulted in