Other Membrane Applications Related to Cheese Making
Even though studies on milk concentration by reverse osmosis and nanofiltration have demonstrated that acceptable quality cheese can be obtained from retentates (Barbano and Bynum, 1984; Mucchetti et al., 2000), several concerns are present that have limited application in the dairy industry. The main issue is excessive retention of concentrated whey into the curd, which leads to higher amounts of lactose and minerals in cheese. This causes abnormal fermentation patterns and foreign flavors, such as metallic and sour. Even though the problem could be resolved by applying diafiltration, concentration of milk by RO is currently performed only in ice-cream manufacturing, as an alternative to the evaporation techniques.
A microfiltration process has been patented that allows the separation of milk fat globule to two fractions: small globules (<2 p) and large globules (>2 p). The two fractions are obtained by microfiltering whole milk, fat enriched milk, or cream on a 2 p ceramic membrane, and present different rheological properties. Small fat globules give creams with finer texture than those containing large fat globules.
Applications to drinking milks, yogurts, sour cream, camembert, Swiss cheese, and butters have been carried out: the use of the small globule fraction yields more unctuous products. The observed results were ascribed to the ability of fat globule membrane components to bind water and to the difference in triglycerides composition. Possible advantages of membrane separation of fat are a reduction in energy consumption and less damage to the fat globule membranes, resulting in enhanced stability of cream and improved sensory properties. A main disadvantage is currently the cost (Goudedranche et al., 2000).
Ultrafiltration of milk whey for the production of whey protein concentrate (WPC) is the classical way to reduce the environmental impact of dairy wastes and gain an economical benefit. Powdered WPC has a wide market in various fields, but the desiccation process cannot be easily performed at the dairy level. Reintroducing the concentrate in the cheese-making cycle can be a possible solution for small and medium dairies to make economically sustainable the implementation of an UF plant for treating whey. Addition of denatured UF whey retentates to milk in order to incorporate whey proteins in cheese has been deeply investigated. Most studies report a detrimental effect on cheese quality, with few exceptions. Better results can be obtained if the whey proteins in the concentrate are subjected to particulation by contemporary heating aggregation and shearing (Hinrichs, 2001; Mead & Roupas, 2001). UF whey concentrate has been successfully employed in the making of ricotta since the end of the 1970s. The protocol introduced by Maubois & Kosikowsky (1978) allowed the process to be continuous without any detrimental effect on the characteristics of the product. A more recent study performed on ovine ricotta concluded that the fortification of fresh whey with UF retentate improves the extent of heat-induced protein aggregation during the thermal coagulation process, allowing better protein recovery and increased yield (Salvatore et al., 2014).