Effect of high-pressure processing on microbial quality of skimmed milk

Abstract

High pressure processing (HPP) is an alternative to traditional thermal treatment and can be used in the dairy industry for increasing the microbiological safety of milk and for preserving its biologically active substances. HPP effectiveness in providing microbiological quality of product is still under discussion; thus, the aim of the study was to evaluate the effect of HPP technology on microbiological quality of skimmed milk. Raw, pasteurised (78 oC, 15-20 s), HPP treated (250 MPa, 15 min; 400 MPa, 3 min; 400 MPa, 15 min; 550 MPa, 3 min) and skimmed milk, processed by combining pasteurisation and HPP were analysed and compared. The total plate count (LVS ISO 4833-1:2013) and presence of coliforms (LVS EN ISO 16654:2002) were determined in analysed skimmed milk samples. Significant decrease (p < 0.05) of colony forming units (CFU) was observed in samples processed by combining two treatment types: pasteurisation and HPP. The minimum treatment parameters for shelf-life extension of skimmed milk were determined: pressure not less than 400 MPa and holding time at least 15 minutes.