Nonthermal concentration of milk by forward osmosis
Concentration of milk in the dairy industry is typically achieved by thermal evaporation or reverse osmosis (RO). Heat concentration is energy-intensive and leads to cooked flavor and color changes. RO is affected by fouling, which limits its final achievable concentration. The objective of this work was to evaluate forward osmosis (FO) as an alternative method for concentrating milk, and study the effects of fat content and temperature on the process. Pasteurized skim and whole milk were concentrated at 4, 15, and 25 °C, using a benchtop FO unit. Water flux and concentration were monitored, and the quality of the concentrates evaluated. All runs were conducted in triplicate, and data analyzed by ANOVA. Flux decreased with time under all processing conditions. Higher temperatures led to less pronounced flux drops and faster concentration for both skim and whole milk. For skim milk, 40 °Brix was reached after 7h at 25 °C, 8.5h at 15 °C, and 10h at 4 °C. Whole milk concentration was slower, with 30 °Brix achieved after 7h at 25 °C, 8h at 15 °C, and 9h at 4 °C. The sensory quality of FO concentrated and thermally concentrated milk, diluted to single-strength and HTST milk was evaluated by a panel, who did not find significant differences between concentrated and un-concentrated milks. This data suggests FO is a viable nonthermal alternative for concentrating milk.
Food science; forward osmosis; low temperature; nonthermal; skim milk; whole milk; Sensory
Moraru, Carmen I.
O'Brien, Kimberly O.
Food Science and Technology
M.S., Food Science and Technology
Master of Science
dissertation or thesis