Ultrafiltration: Partitioning of Milk Constituents into Permeate and Retentate

¹ Department of Nutrition and Food Sciences, Utah State University, Logan 84322

We collected retentate and permeate samples during UF and diafiltration of unacidified and acidified whole milk. After analyzing retentate and permeate, we calculated retention and recovery of fat, total N, rennet clottable N, lactose, Ca, Na, P, and riboflavin. Retention depends on the permeate:retentate ratio of components. Recovery is the component amount in retentate divided by its amount in original milk. Removing permeate from unacidified milk increased retention of total N, Ca, Na, P, and riboflavin. All the fat and rennet clottable N and 1% of lactose were retained. Recovery of these components ranged from 12% for lactose to 100% for fat and rennet clottable N. Retention of lactose, Na, P, and riboflavin was higher during diafiltration than during UF of unacidified milk, but recovery of total N, lactose, Ca, Na, P, and riboflavin was lower. Diafiltration of acidified milk decreased retention of Ca, P, Na, and riboflavin compared with diafiltration of unacidified milk. Changes in constituent retention during UF processes depend on level of concentration, diafiltration, and acidification. Because diafiltration and acidification influence retention and recovery of many milk components, processors can alter pH, rennetability, syneresis, and meltability of cheese (and properties of other derived products).

Key Words: ultrafiltration • retention • permeate

Submitted on December 14, 1990
Accepted on March 26, 1991