Preservation under pressure (hyperbaric storage) at 25°C, 30°C and 37°C of a highly perishable dairy food and comparison with refrigeration

Abstract

Hyperbaric storage (HS) under mild pressure of requeijo, a traditional Portuguese whey cheese, as a case study of a highly perishable dairy food, was evaluated as a possible energy costless alternative to refrigeration. Whey cheese was stored for 4 and 8 hours, at different pressure levels (0.1, 100 and 150 MPa) and temperatures (25C, 30C and 37C), and the results were compared with refrigeration (4C). Microbial analyses showed that storage for 4 hours at 100 MPa was able to maintain microbial counts similar to refrigeration and initial load, 3 Log 10 CFU/g, at all tested temperatures. By increasing the pressure to 150 MPa and the storage time to 8 hours, microbial loads were reduced to undetectable counts, with the exception for total aerobic mesophiles that were reduced to about 1 Log unit. HS in general maintained pH, water activity and lipid oxidation values, at levels similar to that in refrigeration.