Effects of Ultra-High Pressure Homogenization on the Cheese-Making Properties of Milk

Abstract

The effects of single- or 2-stage ultra-high pressure homogenization (UHPH; 100 to 330 MPa) at an inlet temperature of 30 degrees C on the cheese-making properties of bovine milk were investigated. Effects were compared with those from raw, heat-pasteurized (72 degrees C for 15 s), and conventional homogenized-pasteurized (15 + 3 MPa, 72 degrees C for 15 s) treatments. Rennet coagulation time, rate of curd firming, curd firmness, wet yield, and moisture content of curds were assessed. Results of particle size and distribution of milk, whey composition, and gel microstructure observed by confocal laser scanning microscopy were analyzed to understand the effect of UHPH. Single-stage UHPH at 200 and 300 MPa enhanced rennet coagulation properties. However, these properties were negatively affected by the use of the UHPH secondary stage. Increasing the pressure led to higher yields and moisture content of curds. The improvement in the cheese-making properties of milk by UHPH could be explained by changes to the protein-fat structures due to the combined effect of heat and homogenization.

Pre-treatment of cheese milk: principles and developments

“…The adsorption of caseins onto the fat globules has the following implications for cheese-making characteristics of milk: (1) casein surface area in milk is increased, but the amount of micellar casein is reduced; (2) two types of particles with a casein micelle surface layer exist: native casein micelles and casein-covered fat globules; (3) when adsorbed, casein micelles tend to spread over the surface of the fat globule and hence increase in effective surface area but with reduced surfacedensity of κ-casein. The rennet coagulation time (RCT) of unhomogenised milk is generally lower than that of homogenized milk [57,62,135,149]. This is probably related to the larger casein surface area in homogenized milk, as well as the lower surface density of κ-casein.…”

“…The former increases the probability of interactions between particles, whereas the latter, for a subclass of particles, reduces the amount of κ-casein that needs to be hydrolyzed before micellar flocculation is induced. Conflicting reports exist on the influence of homogenization on the rate of rennet-induced gel formation; both homogenization-induced increases [57,62,149] and decreases [135] therein have been reported. Zamora et al [149] reported that, on high-pressure homogenization (100-330 MPa), the rate of gel formation may be either increased or decreased, with no clear trend as a function of homogenization pressure, but large differences in the pH of samples hinder a clear and unequivocal interpretation of these data.…”

“…Cheese curd from homogenized milk shows poor syneresis [32,46,62] and, as a result, has high moisture content. Furthermore, cheese curd prepared from homogenized milk is also often characterized by a coarse and brittle structure [46,135,149].…”

High hydrostatic pressure technology in dairy processing: a review

“…It has been observed that denaturation of whey proteins is due to applied pressure and results in interaction between denatured whey protein and casein, which in turn increases the retention of former within casein matrix of cheese. Thus, these changes result in modifying the technological parameters of milk to make cheese, improving the rennet coagulation properties and yield of cheese (Trujillo et al 1999, San Martin-Gonzalez et al 2004, Zamora et al 2007.…”

Opportunities for Ultra-High-Pressure Homogenisation (UHPH) for the Food Industry

“…3). Upon UHPH, these main peaks merge into a single peak between 0.1 and 0.3 lm depending on the homogenising pressure [93]. It has been observed that milk inlet temperature has a significant effect on the reduction of fat globule size [14,29,81].…”