Characterising Ripening in UF-Cheese

It is possible to manufacture several varieties of cheese from milk concentrated by uitrafiltration (UF-cheese). Often, the UF-cheese types are divided into three categories: (1) cheese from maximum two-fold concentrate, (2) cheese from approximately five-fold concentrate, and (3) cheese from fully concentrated milk. The most fundamental characteristic of UF-cheese is its content of whey protein. UF-cheese in category 1 ripens more or less similarly to traditionally produced cheese. It is well known, however, that the ripening of UF-cheese from five-fold or fully concentrated milk proceeds much more slowly. This means that protein breakdown and flavour development are retarded relative to traditional cheese, even though the overall composition of the cheese (total solids, TS, fat in dry matter, FDM) is the same. Many studies on this phenomenon have demonstrated that this is due mainly to a very slow breakdown of beta-casein in the UF-cheese. The primary hydrolysis of beta-casein is catalysed partly by plasmin. Much evidence suggests that the action of plasmin in UF-cheese is inhibited by beta-lactoglobulin and that this is one of the reasons for the slower ripening of UF-cheese. An understanding of the reasons for the slower ripening of UF-cheese opens up the possibility of improvhtg flavour development in such cheeses. Studies have shown that it is possible to influence flavour development by using starter strains selected for this purpose, by addition of the correct amount of rennet, by addition of proteolytic enzymes or attenuated starters or by increasing the available amount of plasmin by the addition of a plasminogen activator.