Pre-treatment of cheese milk: Principles and developments

Classically, very few pre-treatments are applied to milk for cheese-making, with some cheese varieties simply made from raw whole milk, but most made from pasteurised milk of which the composition (e.g., fat:protein ratio) may have been standardized. However, there has been consistent interest in more novel and sophisticated strategies for pre-treatment of cheese-milk. Approaches explored include the use of alternative processing technologies (e.g., membrane filtration, high-pressure treatment, homogenisation, heat treatments more severe than pasteurisation) or addition of sources of protein or milk solids (e.g., milk powders, whey protein products) or enzymes. The principal reasons for such pre-treatments of cheese-milk are: (1) to control the microbiology of the raw milk and the resulting cheese better than is possible by pasteurisation (e.g., inactivation or removal of spores, control of non-starter lactic acid bacteria); (2) increasing the yield of cheese, e.g., through heat- or pressure-induced incorporation of whey proteins, or enhancing sensory properties of reduced fat cheese by direct addition of microparticulated whey proteins; (3) manipulation of cheese ripening, e.g., reducing the likelihood of off-flavour development by inactivation of enzymes or accelerating ripening through increasing enzyme-substrate interactions; or (4) improving the texture and other functional properties, e.g., melting. Finally, the considerations for manufacture and ripening of different cheese varieties, or sub-classes of specific varieties (e.g., low-fat cheese) will clearly differ and add to the complexity of the technological options available. This article will review the key principles for pre-treatment of cheese-milk, as summarised briefly above.