Combining High Pressure Processing and Low Storage Temperature to Extend the Functionality Shelf Life of Low-Moisture Part-Skim Mozzarella Cheese.

Abstract

High pressure processing (HPP) and low temperature storage (0°C) were explored as alternatives to freezing for extending the performance shelf life of low-moisture part-skim (LMPS) Mozzarella intended for export. Batches (n = 5) of reduced Na LMPS Mozzarella were manufactured using camel chymosin as a lower proteolytic type of rennet. Cheeses were stored for 2 wk at 4°C, divided into control (non-HPP) and HPP (600 MPa for 3 min) groups, and stored at 3 different temperatures (4, 0, and -18°C) for 365 d. Analyses were performed at 0, 90, 150, 210, 270, and 365 d of storage. Frozen and 0°C samples (∼2.3 kg) were thawed/tempered at 4°C for 1 wk before analysis. Urea-PAGE and quantification of the pH 4.6 soluble N over time were used to monitor primary proteolysis. Body and rheological properties were monitored using texture profile analysis (TPA) and dynamic low-amplitude oscillatory rheology. Changes in flavor, body, shred properties, and pizza performance were evaluated using quantitative descriptive analysis with 12 trained panelists using a 15-point scale. HPP treatment caused ∼5 log cfu/ml reduction in starter counts, partial solubilization of the insoluble Ca, and a small pH increase (from ∼5.2 to 5.3). The rate of primary proteolysis was reduced by HPP and low temperature storage. HPP treatment reduced initial cheese hardness, but no further significant decrease was observed over storage time, while the hardness of non-HPP samples decreased over the 365 d of storage, apart from the frozen samples. In pizza applications, blister quantity development and loss of strand thickness were limited by storage at -18°C. Freezing LMPS Mozzarella to -18°C gave the least changes in proteolysis and pizza performance over the 365 d of study, storage of cheese at 0°C slowed the loss of hardness and the deterioration of pizza performance attributes. The combination of HPP and 0°C storage of cheese resulted in little change in blistering quantity of pizza during the 365 d of study, whereas cheese stored at 0°C had blisters covering much of the pizza after this extended storage time. Combining HPP with low temperature storage is a promising alternative approach to freezing for the extension of the functionality shelf life of LMPS Mozzarella.