Low-moisture part-skim mozzarella made from milk with varying casein contents.

Abstract

There is growing interest in manufacturing cheese from concentrated milk as this increases plant productivity and output. Low-moisture part-skim (LMPS) mozzarella is widely used in pizza applications, where its functionality is very dependent on the protein and calcium contents. We explored the effect of using milk with elevated casein levels on the properties of LMPS mozzarella cheese. Ultrafiltration was used to produce cheese milk with 2.5%, 4.0%, and 5.5% casein. All cheese milk was preacidified with lactic acid to pH 6.0, lactic cultures were added, and whey drainage was performed when curd reached pH ∼5.7. We also explored varying the pH value at milling (pH 5.4 and 5.1) for these cheeses to determine if that could be a useful parameter to modify the functionality in cheeses made from concentrated milk. Increasing the casein content of milk resulted in an increase in the total calcium contents. However, all milk had a similar insoluble calcium content when this component was expressed as milligrams per gram of protein, but the ratio of insoluble calcium as a percent of total calcium increased because of the loss of soluble calcium in the permeate. Cheeses manufactured from milk with 5.5% casein had significantly lower moisture contents compared with cheeses made from milk with 2.5% casein. Altering the pH at milling did not cause a significant difference in the total calcium content of cheese but slightly reduced the insoluble calcium content when the curds were milled at pH 5.1 compared with curds milled at pH 5.4. Lower pH values at milling also resulted in lower pH values of the cheeses during storage and lower insoluble Ca levels. Higher instrumental hardness and sensory firmness were observed in cheeses made from milk with higher casein levels. Shred straightness and shred length scores during storage remained higher (and generally acceptable) in cheeses made from milk with higher casein levels. Blister quantity scores on pizza were initially higher (significant blistering) in LMPS mozzarella cheese made from 5.5% casein milk, but by 12 wk of refrigerated storage, principal component analysis (PCA) indicated that blister quantity was now more associated with the cheeses made from lower casein milk. The PCA indicated that cheeses made from higher casein milk were separated from the cheeses made from lower casein milk over the entire storage period. Generally acceptable pizza and shredding performance was observed in all treatments during most of the storage period, likely helped by the preacidification of cheese milk to pH 6.0 and the use of a low pH at whey drainage (∼5.7). The cheese made from high-casein milk retained better functionality (e.g., thicker strands during stretching, longer shreds, and higher firmness) during an extended refrigerated storage. The lower moisture content of the cheeses made from concentrated milk could be easily corrected by adjusting some of the cheesemaking parameters (e.g., cutting conditions or less stirring). Concentrated milk was suitable for producing LMPS mozzarella with desired pizza functionality.