Interaction Between Sodium Chloride and Paracasein as Determined by Water Sorption

The model system, salt-paracasein-water, for binding interactions that influence ripening of salted cheeses was investigated. The amount of salt interacting with protein was calculated from water sorption data in the range 0.76-0.95 aw for the system and for pure salt and protein. Calculations showed that the components did not behave independently in that the system behaved less like salt and more like paracasein than expected, evidencing interaction between salt and protein. The amount of interacting salt increased with added salt, decreasing aw, moisture content during preparation and drying the system. At 0.85 aw the amount of interacted salt was 0.08 g/g protein when the salt added was 0.30; the maximum interacted salt was about 0.11.