Abstract #W146

# W146
Evaluation of a Centritherm evaporator for concentrating micellar casein.
Anil Kommineni1, Dustin Grossbier*1, Steven Beckman1, Ananya C. Biswas1, Lloyd E. Metzger1, 1Midwest Dairy Foods Research Center, Dairy Science Department, South Dakota State University, Brookings, SD.

Micellar casein is produced by micro-filtering skim milk. In a typical skim milk microfiltration (MF) process the retentate produced has approximately 10% protein and 12% total solids. After MF this retentate can be further concentrated before spray drying. In previous research we determined that micellar casein could be concentrated to approximately 25% solids using a falling film vacuum evaporator. However, concentration beyond 25% solids was challenging due to the high water binding and film forming characteristics of micellar casein. As compared with falling film evaporation, a Centritherm evaporator (CTE) is a thin film vacuum evaporator that can be used to concentrate highly viscous products. In a CTE the feed tube distributes product on the underside of a rotating heating cone through a feed nozzle. Steam is injected on the opposite side of the cone thereby heating the product stream through conduction. Centrifugal force of the rotating cone creates a thin, turbulent layer, which gives a residence time of 1sec with a high heat transfer coefficient. The objective of this study was to evaluate the CTE for concentrating micellar casein. In this study, 3 replicates of micellar casein with 12% solids were manufactured by micro filtration of skim milk and then used as feed for the CTE. Initial trails were conducted to find the optimum evaporation conditions for minimal fouling. The heating temperature of 80°C, boiling temperature of 50°C and feed rate of 50 L/h were determined as optimal. Each replicate of micellar casein was passed through the CTE 3 times. The average water evaporation rate in each pass and the total solids of the concentrate was determined. The total solids content of the final micellar casein for each replicate was 22.49, 21.92, and 22.93%. The mean water evaporation of each pass was 6.17, 5.92, and 3.83% respectively for pass one, 2, and 3. The decreasing water evaporation rate with each pass may be a result of increased water binding as the solids content of the micellar casein increased. The results indicate that the CTE concentrated micellar casein similar to falling film evaporation.

Key Words: micellar casein, Centritherm evaporator