Processing of phosphocasein dispersions by dynamic high pressure: Effects on the dispersion physico-chemical characteristics and the binding of I+/--tocopherol acetate to casein micelles

Dispersions of phosphocaseins (PCs) containing (w/w) 2.5% proteins at pH 6.7 were processed using a ~ 15 L/h homogeniser with a high-pressure valve immediately followed by cooling devices. The effect of dynamic high-pressure (or ultra-high pressure homogenisation, UHPH) at 100-300 MPa and two initial temperatures (T sub(in) = 14 degree C or 34 degree C) was investigated on (i) casein micelle size distributions, (ii) the turbidity and viscosity of PC dispersions, and (iii) the binding efficiency of alpha -tocopherol acetate ( alpha -TA) to casein micelles ( alpha -TA:PC molar ratio ~ 1:1). A significant and gradual decrease of casein micelle sizes was observed after UHPH up to 300 MPa at T sub(in) = 14 degree C. The decrease in micelle sizes was less extensive after UHPH at T sub(in) = 34 degree C. Notably, the binding efficiency of alpha -TA significantly (p < 0.001) increased after processing, suggesting combined effects of temperature and dynamic high-pressure. Industrial relevance: Industrial operators in food, cosmetic and pharmaceutical areas are currently interested in developing encapsulating systems to delivery bioactive compounds, generally hydrophobic, unstable and sensitive to light, temperature or/and oxygen. The present study suggests that processing of casein micelle dispersions by dynamic high pressure at greater than or equal to 200 MPa could modify casein micelle organisation with an enhancement of the binding of hydrophobic ligand ( alpha -tocopherol acetate) to the newly UHPH-formed neo-micelles. Here is a potential application for UHPH, a physical technology that offers the added advantage of notably reducing the microbial load of processed samples.