Synthetic Milk for the Study of Cheese Making. I. Preparation of a Casein Sol in Semblance of Skimmilk

Abstract

A method of preparing a casein sol similar in salt composition to skim-milk is described. The success of the method depends upon a definite order of combining salt components with purified casein at low temperature. The preparation of the synthetic skimmilk observes certain conditions: the order of salt addition permits precipitation of the ion components of the least soluble salts in stable colloidal form in the presence of soluble caseinates, and does not cause irreversible changes in casein; the order of salt incorporation controls pH to minimize casein hydrolysis; temperatures used increase solubility of the less soluble milk salts, including proteinates, without decreasing chemical reaction rates to an impractical point, and minimize casein hydrolysis; and mass transfer is accelerated by agitation. Electrophoretic patterns of casein recovered from the sol show the method does not have a detrimental effect upon casein. The casein sol reacts with rennet like skimmilk in that it shows a similar coagulation rate and curd tension development. The casein sol resembles milk in that its curd tension is not affected by adding limited amounts of lactose but is decreased by adding whey protein and emulsified butter fat. These properties of the sol suggest that it should be useful for studies of milk-coagulating enzymes, milk fermentations, and curd-making processes.