Production and storage stability of liquid micellar casein concentrate.
American Dairy Science Association
Journal of Dairy Science
microfiltration, micellar casein, shelf life
Micellar casein is a high protein ingredient that can be used as a valuable source of intact casein in process cheese formulations. The objective of this study was to produce a highly concentrated micellar casein (HC-MC) and evaluate its storage stability. Skim milk was pasteurized at 72°C for 16 s and kept at ≤ 4°C until the following day when it was heated in a plate heat exchanger to 50°C and microfiltered with a ceramic GP MF system (0.1μm) in a feed and bleed mode to produce a 3 × MF retentate (1 kg of retentate:2 kg of permeate). Subsequently, the retentate was diluted 2× with soft-water (2 kg of water:1 kg of retentate) and again microfiltered at 50°C to a 3× concentration as described previously. The retentate was then cooled to 4°C, and stored overnight. The following day, the retentate was heated to 65°C and microfiltered in a recirculationmode until the total solid reached approximately 22%. Subsequently, the temperature was increased to 74°C and microfiltration was continued until the permeate flow rate reached less than 5 L/h. The HC-MC retentate was transferred at 74°C to sterilized vials and stored at 4°C. This trial was repeated 3 times using 3 separate batches of raw milk. During microfiltration, the mean cumulative SP removal in the first, second, and third stages was 46, 77, and 83%, respectively. The mean HC-MC at time zero contained 25.42% total solids (TS), 20.20% true protein (TP), 0.09% NPN, 0.55% NCN, 19.80% CN, 2.0% ash, 97.70% CN%TP, and 0.45% SP. The NCN content increased significantly (P < 0.05) from 0.55 to 0.76% during 2 mo of storage. The NPN also increased over time from 0.095% at time zero to 0.12% after 2 mo of storage. The mean aerobic bacterial count in HC-MC at time zero was 2.6 ± 0.16 log cfu/mL and increased to 3.5 ± 0.89 and 4.3 ± 0.97 log cfu/mL after 1 and 2 mo of storage, respectively. Coliform, yeasts, and mold were not detected at any time point. This study determined that HC-MC could be manufactured using ceramic MF membranes with over 25% TS and greater than 95% CN%TP. The impact of the small increase in NCN and NPN during 2 mo of storage on process cheese characteristics will be evaluated in subsequent studies.
Hammam, A. R. A. and Metzger, L. E., "Production and storage stability of liquid micellar casein concentrate." (2018). Dairy Science Publication Database. 1975.