Fresh cut pineapple cubes inoculated with 104h5 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 0È270 MPa using 0É5-s and 10-s pulses. Inoculated treated and untreated samples were held at 4¡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 \240 CFU g~1 yeast and bacteria counts for up to 60 days. Step-pulsed pressure treatments for 100 s at 0È270 MPa using 0É5-s (200 pulses) and 10-s pulses (10 pulses) were more e †ective than a 100-s static 270-MPa treatment.
Step-pulsed pressure treatments (300 and 600 s) using 0É5-s pulses (600 and 1200 pulses) and 10-s pulses (30 and 60 pulses) were as e †ective as 9000-s static pressure treatments at 270 and 340 MPa. This storage study conÐrmed the superiority of step-pulsed over static pressure treatments.
1998 SCI.