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Summary
The pH of milk at setting affects the properties of mozzarella cheese made by direct acidification. Milk protein concentrate (MPC) containing approximately 64% protein, 20% lactose and 2% calcium was used to standardise whole milk to a protein to fat ratio of ~1.3 for the manufacture of low-moisture partskim (LMPS) mozzarella cheese. Our objective was to compare the effect of setting pH (pH 5.6, 5.8 or 6.0) of whole milk standardised with MPC on LMPS mozzarella cheese made by direct acidification. Standardised, pasteurised (72°C x 16 s) milk was divided into three lots - A, B and C - and adjusted to pH 5.6, 5.8 and 6.0, respectively, with 2% citric acid prior to setting (5 mL chymosin / 100 kg milk) and mozzarella cheesemaking in triplicate trials. All cheeses were stored at 4°C for 35 days. Composition, yield, meltability, baking properties and the hardness of the cheeses were determined by standard methods; primary proteolysis was assessed by urea-polyacrylamide gel electrophoresis and the determination of water-soluble N contents of the cheeses. Significant differences (p<0.05) in the percentage moisture (51.54 ± 2.09, 50.87 ± 2.32, 47.94 ± 1.85) and calcium contents (367.5 ± 1.2, 457.6 ± 4.2, 537.5 ± 2.1 mg/kg cheese) were found for cheeses A, B and C, respectively. No significant (p>0.05) differences were observed in lactose, protein, fat, protein or fat recovery, and yield of the cheeses. The percentage total solids recovered in the cheese decreased with a reduction in pH setting of the milk. Direct acidification to of milk with a set pH of 5.6 or 5.8 produced mozzarella cheese that was softer and melted better than cheese set at pH 6.0.
Aust. J. Dairy Technol. 61, 8-12
Introduction
Mozzarella cheese constituted 32.7% of the total cheese produced in the United States in 2002 (USDA 2003). About 70% of the mozzarella cheese produced in the US is used in pizza manufacture. Mozzarella cheese is manufactured either by a culture acidification method or a direct acidification method. In direct acidification, cheese milk is acidified with food-grade acid or acidogen to pH (5.6-5.8) prior to cheesemaking. Acidification of milk results in the loss of colloidal calcium phosphate from casein micelles into the milk serum (van Hooydonk et al. 1986) and its...