High-Temperature-Short-Time Sterilized Evaporated Milk. IV. The Retardation of Gelation with Condensed Phosphates, Manganous Ions, Polyhydric Compounds, and Phosphatides

Abstract

Summmary Polyphosphates, manganous salts, polyhydric compounds, and phosphatides are important additives for prolonging the storage life of high-temperature-short-time sterilized milk concentrates. A sixfold and threefold increase in the storage life of 3 to 1 and 2 to 1 concentrates was, respectively, obtained by adding per 100g milk 0.05g sodium polyphosphate containing an average of 4.8 P atoms per chain; and a similar increase was obtained by adding approximately the same quantity of MnSO 4 . In concentrations greater than about 1g per 100g milk solids, the polyphosphate conduced to age-thickening. The polyphosphates function also as stabilizers against heat coagulation during sterilization. The antigelation activity of the polyphosphates increased with increasing concentration and chain length. The cyclic tetrametaphosphate and adenosine triphosphate were more effective than the corresponding linear polymer and sodium tripolyphosphate, respectively. Added orthophosphates were found to conduce to gelation. Nearly a twofold increase in storage life was brought by the incorporation in 2 to 1 concentrates of 9.6g per 100g product of either lactose, sucrose, dextrose, or sorbitol. At higher concentration levels specific effects were met which limited the activity of the sugars, but not that of sorbitol. In stabilizing the lipid phase, added phosphatides stabilize HTST sterilized milk concentrates both against heat coagulation during sterilization and gelation during storage. Theoretical considerations postulating the existence of two kinds of micellar structures, one active in gelation phenomena, the other in heat coagulation, served as a guide in the selection of the additives used in the present study.