Development of UF Applications in the Cheese Industry
MMV Process. (Maubois et al., 1969) Concentrate to 5 - 7 x original milk protein content, add both starter and rennet, incubate until both coagulation and lactic fermentation are complete, and ripen. MMV is most successful for some fresh and soft-ripened cheese varieties which have relatively low total solids and do not require rigorous pH control. It has been most successful for Feta cheese. The chief difficulty is that the MMV process produces close textured cheese which has led to two types of Feta: (1) Structured or conventional Feta and; (2) UF or cast Feta. The MMV process can also be used to manufacture cheese base to extend young Cheddar in process cheese formulations. The amount of UF retentate in process cheese products is limited by the presence of whey protein in the retentate which impairs meltability of the cheese.
The LCR Process. LCR stands for low concentrated retentate. Milk is concentrated 1.5 - 2 x original milk protein content. Cheese is made using minor modifications to traditional procedures. LCR is now the principal process used in French Camembert providing the advantages of slightly higher yields, labour savings, facilitation of continuous cheese making, and increased plant capacity. Most types of hard cheese have been made by LCR principles with varying degrees of success.
UF retentates in the mid range of concentration (2 - 5 x original protein content) have not been successful with the possible exception of Feta. It is possible to produce higher yields of Feta than via conventional means by heat treating retentate at sufficient levels to denature whey proteins. Normally this would impair rennet function, but UF treatment restores rennetability. The result is that denatured whey proteins are incorporated into the rennet gel, thus increasing cheese yield. This permits manufacture of a structured Feta, similar to traditional products, while realizing significant yield improvement. This practice has been successful for Feta but not for most rennet cheese because the whey proteins impair meltability and produce a coarse textured cheese.
TABLE 22.1 Ultrafiltration of whole milk. Typical composition of concentrate and permeate System: polysulfone membrane in tubular configuration, small pilot plant, batch operation at 50C (Glover, 1985).