PROPERTIES OF DISPERSIONS OF SOYA AND WHEY PROTEINS - A TECHNOLOGICALAPPROACH

Soya protein, after extraction and isolation from soya beans, does not readily disperse in aqueous media or dairy-like systems. A procedure was developed for preparation of milk-like and concentrated milk-like dispersions containing particles of soya protein instead of casein mic elles. Stable dispersions of whey powder and commercially available so ya protein isolate in water could be prepared with a homogenizer at pr essures over 5 MPa. Dispersion stability, assessed by particle size an d amount of sediment in a mild centrifuging test, was improved by rais ing pH, increasing temperature, emulsifying fat and, under some condit ions, by increasing homogenizing pressure. It was hardly affected by N a+, whereas Ca2+ had a detrimental effect. Concentrated dispersions co uld only be prepared with demineralized whey powder. Creaming stabilit y of emulsions of soya and whey proteins was heavily dependent on mass ratio of protein to fat and homogenizing pressure. Heat stability of dispersions of soya and whey proteins was good. Concentrated (evaporat ed) milk-like dispersions could be heated for a prolonged time at 130- degrees-C. Dispersion stability and creaming stability of dispersions of soya and whey proteins and of emulsions were not so good as of (ski m-)milk and concentrated milk, whereas heat stability was better.