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

摘要

Dispersions of phosphocaseins (PCs) containing (w/w) 2.5% proteins at pH 6.7 were processed using an approx. equal to 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_in=14 degrees C or 34 degrees 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 approx. equal to 1:1). A significant and gradual decrease of casein micelle sizes was observed after UHPH up to 300 MPa at T_in=14 degrees C. The decrease in micelle sizes was less extensive after UHPH at T_in=34 degrees 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 >=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