Extension of the shelf life of prawns (Penaeus japonicus) by vacuum packaging and high-pressure treatment

The present study has investigated the application of high pressures (200 a nd 400 MPa) in chilled prawn tails, both conventionally stored lair) and va cuum packaged. Vacuum packaging and high-pressure treatment did extend the shelf life of the prawn samples, although it did affect muscle color very s lightly, giving it a whiter appearance. The viable shelf Life of 1 week for the air-stored samples was extended to 21 days in the vacuum-packed sample s, 28 days in the samples treated at 200 MPa, and 35 days in the samples pr essurized at 400 MPa. Vacuum packaging checked the onset of blackening, whe reas high-pressure treatment aggravated the problem. From a microbiological point of view, batches conventionally stored reached about 6 log CFU/g or even higher at 14 days. Similar figures were reached in total number of bac teria in vacuum-packed samples and in pressurized at 200-MPa samples at 21 days. When samples were pressurized at 400 MPa, total numbers of bacteria w ere below 5.5 log CFU/g at 35 days of storage. Consequently, a combination of vacuum packaging and high-pressure treatment would appear to be benefici al in prolonging freshness and preventing spotting.