Fractionation of milk fat by falling film layer crystallization

Abstract

Falling film layer crystallization (FFLC) is a promising approach to milk fat fractionation into oil and plastic fat fractions and can be an alternative to the conventional suspension melt crystallization (SC). The fractionation of milk fat by means of the FFLC process was investigated. Efforts were focused on the maximization of the stearin yield with satisfactory separation efficiency. The performance of the FFLC was also compared with that of the SC process. The experimental runs were conducted at varied Reynolds numbers ranging from 5 to 75, crystallization temperatures from 28 to 32°C, and sweating temperatures from 36 to 39°C, at a constant cooling rate (0.1°C/minute) and a crystallization time of 3 hours. The sweating step was necessary and acted as a refinement step to remove low-melting triglycerides that adhered to crystals. A difference in dropping (melting) points of stearin and olein fractions of 12°C and a stearin yield of 20% were obtained at a crystallization temperature of 30°C, Reynolds number of 12, and sweating temperature of 36°C. The dropping point of the stearin fraction reached 45°C compared with 31°C for the olein fraction, and 33°C for milk fat. Falling film layer crystallization and SC processes were comparable in terms of solid yield, as well as physicochemical properties of the fractions.