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. High-pressure processing 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. High-pressure processing treatment reduced initial cheese hardness, but no further significant decrease was observed over storage time, whereas 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.