The ultrafiltration (UF) method for white cheese production was introduced in the early 1970s and has been widely used ever since. Membrane filtration is an established and proven technology for nearly any dairy process, and Tetra Pak Filtration Solutions has supplied and installed more than 30 UF plants for white cheese production around the world. The UF process offers a number of advantages.
With traditional cheese making in vats, only the casein and fat is retained in the cheese. With the UF method, whey proteins as well as casein and fat is retained. In consequence, the UF method requires approximately 20% less milk per kilo cheese.
The need for rennet addition is to a great extent related to volume. In the traditional vat process, it is necessary to rennet the entire milk volume, whereas in the UF method, only the concentrate volume needs renneting. The concentrate volume is typically 5 times less than the milk volume. Accordingly, the rennet consumption will be considerable lower when using the UF method.
The same UF plant can produce concentrate with a wide variety of compositions i.e. fat in dry matter, and dry matter in concentrate. Product change from one type to another can be handled in fully automatic process control systems via recipe handling. At the same time, the possibility to switch recipes on the same plant offers an excellent opportunity to introduce new products without having to invest in new equipment.
In the traditional vat process, virtually all protein in the cheese is casein; in the UF process, the protein in the cheese consists of both casein and whey proteins. The nutritional value of whey protein is higher than that of casein. Hence, the total nutritional value of the finished product is higher when made by UF.
The traditional cheese making process in vats is by nature a batch process. The UF method is a true continuous process; standardised and pasteurised milk is fed into the UF plant, and concentrate leaves the plant in a continuous flow. The UF process is extremely fast, requiring an average of less than 10 minutes from the milk enters until the concentrate leaves the plant.
Cheese vats used in traditional process are open or semi open and as such sensitive to contamination from microorganisms in the air, especially yeast and mould. The UF process is a fully closed system and therefore not subject to airborne contamination. The benefit is prolonged product shelf life and less waste due to spoilage.
The traditional cheese making process in vats is very sensitive to several process parameters: temperature, milk acidity, rennetability, coagulum cutting, mechanical stirring and time in the vat. All those parameters are controlled by the cheese maker and based on his knowledge and experience. The UF process eliminates some of the variables with a fully automatic process control system ensuring a uniform concentrate at all times.