Physical and Flavor Stability of Frozen Milk Dialyzed Against Simulated Ultrafiltrates

Frozen milk and its 3:1 concentrate were stored 30 wk at 15 F without cascinate instability by conditioning their composition as follows:(a) About 50~ lactose was removed by dialysis against a simulated milk ultrafiltrate of average composition devoid of lactose.(b) Soluble calcium partially removed by dialysis against an ultrafiltrate devoid of calcium.Method (b) gave a stable product for 30 wk at 15 F even in the presence of 20% lactose.Partial relnoval of phosphorus promoted instability, indicating that precipitation of Ca:,(P0~)~ in frozen milk and its interaction with the caseinate micelle is not the main factor responsible for instability.Delaetosed milk had a flat flavor that can he corrected by adding the balance of lactose upon reconstitution.Milk with part of its calcium removed by dialysis against an ultra~ltrate had a flavor comparable to normal milk.Delactosed milk did not have the strong oxidized flavor developed in regular nfilk and its concentrate.This is due to removal of proxidant copper by dialysis.Adding 1 ml 0.00045 5~ neocuproine to chelate copper prevented the development of oxidized flavor in nondialyzed milk.