Preservation of high pressure pasteurised milk by hyperbaric storage at room temperature versus refrigeration – Effect on natural microbiota and physicochemical properties

Abstract

Compared to refrigeration (RF), hyperbaric storage (HS) has been applied as a preservation methodology to increase foods shelf-life. The aim of this study was to compare HS at naturally variable uncontrolled room temperature (RT) to RF and evaluate its feasibility to preserve high pressure pasteurised milk (HPP milk), using different pressure levels (50, 75 and 100 MPa), by testing microbial and physicochemical parameters.While RF merely inhibited microbial growth over 40 days, HS/RT (75/100 MPa) maintained pH and gradually reducing all endogenous microorganisms tested to below the detection limit (< 1.0 log CFU/mL) corresponding to at least 2.60 log CFU/mL reduction on total aerobic mesophiles. Additionally, total soluble solids and apparent viscosity could both be kept using HS/RT for at least for 21 days. For 40 days, the total colour difference showed a small but discernible change for RF and HS/RT conditions, being also observed an increase on soluble protein for HS/RT samples, which may have resulted by pressure leading to aggregation of micelle caseins and whey proteins.In conclusion, the present work showed the potential of HS to preserve HPP milk with longer microbial shelf-life compared to RF and with a minor impact on physicochemical properties, being more environmentally friendly and sustainable than conventional RF.