Influence of Sodium Chloride on Appearance, Functionality, and Protein Arrangements in Nonfat Mozzarella Cheese

Nonfat Mozzarella cheese curd was manufactured in 227-kg batches on 3 separate d using direct acidification. Cheeses with differing NaCI concentrations were obtained by dividing curd into separate lots that received various applications of dry NaCI (0, 0.5, and 1.0% NaCI, wt/wt) and hot brine (0, 5, and 10% NaCI, wt/vol) stretching treatments. The NaCI, Ca, ash, fat, moisture, and protein contents as well as cheese meltability and expressible serum of each cheese were determined. In addition, observations were made on cheese color and functionality over 24 d of storage at 4C. Transmission and scanning electron micrographs of unsalted and salted cheeses were evaluated to determine the differences in the protein matrix. The type of NaCI application and the NaCI content of the cheeses influenced the cheese moisture, meltability, expressible serum, microstructure, and ultrastructure. The moisture content was highest in cheeses in which the curd was salted before stretching. The melt was the lowest in cheeses that were unsalted. Cheeses that were stretched in either 5 or 10% brine had <1% of the amount of expressible serum observed in unsalted cheese. Unsalted cheeses had a more open structure than did salted cheeses. Pockets of free serum were distributed throughout the protein matrix of the unsalted cheese, thus producing light-scattering surfaces and making the cheese opaque. In contrast, the salted cheeses had a more homogeneous protein matrix that lacked lightscattering surfaces, resulting in a translucent cheese. Neither NaCI concentration nor method of salting affected ..the Ca content of the cheeses.