Influence of homogenization of concentrated milks on the structure and properties of rennet curds

Abstract

SummaryWhole milk was concentrated by ultrafiltration in a plant causing some homogenization of the fat. Comparisons were made with milk concentrated in a plant causing little homogenization and with milk homogenized conventionally. None of the processes appreciably affected the casein micelle size distribution. On rennet treatment of homogenized milk, casein micelle aggregation occurred more slowly, the protein network in the curd was less coarse and the rate of whey loss was reduced, compared with non-homogenized milk at the same concentration. In using concentrated milks for cheesemaking homogenization improved the composition of Cheddar cheese, because of increased fat and moisture retention, but curd fusion was poorer. Some aspects of the texture of the mature cheeses were improved, but the free fatty acid levels were higher. Values for the firmness of curds, formed from milks processed in different ways, did not relate to the extent of aggregation of the casein micelles. It is suggested that the complete cheesemaking process is driven by the tendency of the casein to aggregate.