Ultra-High Pressure Pasteurization of Fresh Cut Pineapple

Ultra-high pressure (200, 270 and 340 MPa), temperature (~4, 21 and 38°C), and time (5, 15, 40 and 60 min) combinations were evaluated as a means to extend the shelf-life of fresh cut pineapple chunks. Cut pineapple obtained from an industrial processor was packed in heat-sealed polyethylene pouches. Triplicate samples were temperature adjusted and treated in an Autoclave Engineers IP2-22-60 isostatic press. Surviving bacteria and total yeast and mold counts were determined using plate count agar (PCA) and acidified potato dextrose agar (PDA), respectively. At the highest pressure (340 MPa) and 15 min, decimal reductions measured by growth on PCA were 3.0 (~4°C), 3.1 (21°C) and >2.5 (38°C). Pressure treated pineapple pieces had PCA counts < 50 colony forming units (CFU)/g. At 270 MPa and 15 min, greater than two decimal reductions were observed only at 38°C. Exposure to pressures of 200 MPa resulted in about one decimal reduction in PCA counts for all temperature and time combinations tested. PDA counts followed a similar behavior for all pressure treatments.