Fat and carotene oxidation in Cheddar cheese may give rise to bleached areas surrounding slits in the cheese and to a tallowy flavour. It was shown that direct contact of the fat with atmospheric oxygen was essential for oxidation to occur, and examination of cheeses showed that slits running from the rind into the interior provided this contact. Factors enhancing slit formation such as gas production by bacteria and mechanical shock to the cheese were shown to increase the incidence of tallowy discoloration. Factors which tended to exclude oxygen such as waxing the cheese surface, wrapping the cheese in plastic film or sealing in a tin were shown to reduce the incidence of the fault or eliminate it.

Accelerating factors were shown to be low cheese storage temperature, excess moisture in the cheese and possibly low salt content. Various factors which may be relevant to a commercial cure for discoloration are also discussed.