Rennet coagulation of heated milk: A review

Mild heat treatments, such as thermisation or pasteurisation, are applied to milk to prevent microbiological problems occurring during or after cheese manufacture. Heating milk in more severe conditions induces the denaturation of serum protein and increases cheese yields. However, the rennet coagulation properties of milk are severely impaired by high heat treatments. Cheeses made from heated milk tend to have a higher moisture content and may show defective body, texture or flavour. The challenge for cheese-makers is to increase yields while minimising the undesirable changes in milk coagulation and cheese quality. This paper reviews the mechanisms of rennet-induced coagulation of milk and the detrimental effects induced by heat. Methods that have been proposed to improve renneting properties of heated milk are also described.