In recent years, many dairy product manufacturers pasteurize milk at temperatures higher than 72degreesC, so as to reduce further the risk of survival of Mycobacterium avium ssp. paratuberculosis. However, little information is available on the effect of these temperatures on cheese quality. Half-fat Cheddar cheeses (similar to15%, w/w, fat) were manufactured from milk pasteurized at 72degreesC, 77degreesC, 82degreesC or 87degreesC for 26 s, and analyzed over a 360 d ripening period. The mean levels of whey protein denaturation in the pasteurized milks were 2.8%, 8.4%, 20.2% and 34.1% of total whey protein, respectively. Increasing pasteurization temperature significantly increased the levels of moisture and non-expressible serum and decreased the levels of protein, fat, calcium and free oil. Pasteurization temperature did not significantly affect the levels of pH 4.6-soluble N but influenced the degradation profiles of 1,1 and beta-caseins. Increased pasteurization temperature significantly reduced fracture stress, fracture strain and firmness of cheeses. Raising the pasteurization temperature from 72degreesC to either 82degreesC or 87degreesC significantly reduced the flowability and stretchability of the heated cheese and increased its apparent viscosity; in contrast, increasing pasteurization from 72degreesC to 77degreesC did not affect these properties. (C) 2004 Elsevier Ltd. All rights reserved.