Pilot scale production process of micellar casein concentrate powder

Micellar casein concentrate (MCC) powder, a new milk protein product produced by a combination of processes including membrane separation, evaporation and spray drying has potential applications in cheese making, whipped topping, coffee whitener and yogurt making. It is becoming more and more popular in the food processing industry, but currently China depends on imported MCC mainly from developed countries. The main objective of this study was to successfully develop a pilot scale production process for micellar casein concentrate powder and facilitate its rapid adoption and manufacturing in China's dairy plants. Preliminary studies involved the selection of a suitable hollow fiber ceramic membrane for the separation of casein micellar and serum protein between 100 nm and 40 nm pore size hollow fiber ceramic membranes (InoCep, Hyflux Ltd, Singapore). The 40nm pore size hollow fiber ceramic membrane, which had better separation performance, was chosen for further investigation on optimum operating parameters, mainly temperature and pressure. A four-stage diafiltration process was employed, in which chemical composition and flux changes were measured at the end of every stage in the production line. Finally, the micellar casein concentrate powder made after evaporation and spray drying process was compared with commercial MCC (Proteinco Inc., Quebec, Canada) in terms of their physical characteristics and chemical compositions. The yield rate and the production costs were also calculated. The results showed that: (1) the permeate of 100 nm pore size membrane was cloudy but the permeate of 40 nm pore size membrane was clear in appearance and the proportion of casein in the true protein of the permeate for the 100 and 40 nm pore size membrane were 40.03% and 17.48%, respectively. Therefore, the 40nm pore size membrane was found to be more suitable for the separation of casein micellar and serum protein and its average permeate flux during a 3×concentration at the optimal operating conditions (temperature 50℃, pressure 2×105 Pa) was above 60 L/(m2·h); (2) the best time for adding water during the whole diafiltration process was when the volume concentration factor was equal to 3, which reduced membrane fouling and enhanced average stage flux. After four stages of the continuous diafiltration process, the casein micellar purity and the pure protein content (on a dry basis) reached 93.34% and 88.15%, respectively; (3) at the end of the diafiltration process, the water flux declined by 39.98%, and when a biological-enzyme cleaning agent was used, water flux recovery was 98.02% of the initial; (4) The solubility of the pilot scale produced MCC was significantly different from that of the commercial MCC. The solubility was better in the pilot scale produced than commercial MCC, which may be due to the difference of the inlet temperature of spray drying. Additionally, the particle morphologies of the pilot scale-produced MCC, as observed by a scanning electron microscope, appeared spherical and smaller in size, whereas the commercial MCC had wrinkled particle surfaces and large particle sizes. (5) From the chemical analyses, determinations of total solids, lactose, minerals, total protein, true protein, casein protein and serum protein content were done but there were no significant differences (p<0.05) between the pilot scale produced and the commercial MCC. (6) In order to produce 1 kg MCC, 46.24 L raw milk was required and the production cost of MCC was calculated as 244.58 Yuan/kg, which was deemed profitable and therefore can be transformed to the industrialized production stage. The methods and data stated in this study are valuable and useful to the industry and as a benchmark for further studies. They can also be used both as a reference and guide for MCC production in China.