High pressure treatment of bovine milk: effects on casein micelles and whey proteins

Abstract

Effects of high pressure (HP) on average casein micelle size and denaturation of α-lactalbumin (α-la) and β-lactoglobulin (β-lg) in raw skim bovine milk were studied over a range of conditions. Micelle size was not influenced by treatment at pressures <200 MPa, but treatment at 250 MPa increased micelle size by ∼25%, while treatment at [ges ]300 MPa irreversibly reduced it to ∼50% of that in untreated milk. The increase in micelle size after treatment at 250 MPa was greater with increasing treatment time and temperature and milk pH. Treatment times [ges ]2 min at 400 MPa resulted in similar levels of micelle disruption, but increasing milk pH to 7·0 partially stabilised micelles against HP-induced disruption. Denaturation of α-la did not occur [les ]400 MPa, whereas β-lg was denatured at pressures >100 MPa. Denaturation of α-la and β-lg increased with increasing pressure, treatment time and temperature and milk pH. The majority of denatured β-lg was apparently associated with casein micelles. These effects of HP on casein micelles and whey proteins in milk may have significant implications for properties of products made from HP-treated milk.

High hydrostatic pressure technology in dairy processing: a review

“…With the application of HHP the size and number of casein micelles increases (as casein micelle dissociates into submicelles due to weakening of hydrophobic and electrostatic interactions between sub micelle and further aggregation of sub micelle to big cluster) as spherical particles change to form chains or clusters of sub-micelles (Huppertz et al 2006). This reduces the rennet coagulation time.…”

Effects of high pressure on functionality of whey protein concentrate and whey protein isolate

“…Higher pressures (above 300 MPa) have irreversible and extensive effects on proteins, including denaturation due to unfolding of monomers, aggregation and formation of gel structures [5]. The extent of high-pressure-induced denaturation of whey proteins increases with treatment time [21,22], treatment temperature [17] and pH [2]. The application of pressure has a disruptive effect on intramolecular hydrophobic and electrostatic interactions.…”

Effects of High-Pressure Technology on the Functional Properties of Milk and Fermented Milk Products

“…Acidification of yoghurt milk with GDL (glucono-δ-lactone) at 200 MPa for 20 min resulted in fine coagulum, homogeneous gel than that of heat treated milk [19,22,36].…”

“…Thus, these changes could lead to modifications of the technological parameters of milk used in cheese-making to improve the rennet coagulation properties and cheese yield (Fig. 2) [19,36]. …”

“…In dairy food processing HHP is used for milk stabilization and to define the pressure-induced structural modifications of the main milk constituents (caseins, whey proteins, fat globules, enzymes), inactivation of microorganisms, depression of freezing point of water, and recovery of lactose and proteins from dairy waste water (nutraceuticals, drugs, food additives [1,7,11,[19][20][21][22].…”