Impact of freezing on the physicochemical and functional properties of low–moisture part–skim mozzarella

Ice crystallization and structural changes in cheese during freezing and frozen storage: implications for functional properties

Temperature-mediated preservation techniques offer a simple, scalable, effective, and fairly efficient method of long-term storage of food products. In order to ensure the uninterrupted availability of cheese across the globe, a critical understanding of its techno-functional properties as affected by freezing and frozen storage is essential. Detailed studies of temperature-mediated molecular dynamics are available for relatively simpler and homogeneous systems like pure water, proteins, and carbohydrates. However, for heterogeneous systems like cheese, inter-component interactions at sub-zero temperatures have not been extensively covered. Ice crystallization during freezing causes dehydration of caseins and the formation of concentration gradients within the cheese matrix, causing undesirable changes in texture-functional attributes, but findings vary due to experimental conditions. A suitable combination of sample size, freezing rate, aging, and tempering can extend the shelf life of high- and low-moisture Mozzarella cheese. However, limited studies on other cheeses suggest that effects and suitability differ by cheese type, in most cases adversely affecting texture and functional attributes. This review presents an overview of the understanding of the effects of refrigeration, freezing techniques, and frozen storage on structural components of cheese, most prominently Mozzarella cheese, and the corresponding impact on microstructure and functionality. Also included are the mechanism of ice formation and relevant mathematical models for estimation of the thermophysical properties of cheese to assist in designing optimized schemes for their frozen storage. The review also highlights the lack of unanimity in critical understanding concerning the effect of freezing on the long-term storage of Mozzarella cheese with respect to its functionality.

New Insights into Cheese Microstructure

Microscopy is often used to assist the development of cheese products, but manufacturers can benefit from a much broader application of these techniques to assess structure formation during processing and structural changes during storage. Microscopy can be used to benchmark processes, optimize process variables, and identify critical control points for process control. Microscopy can also assist the reverse engineering of desired product properties and help troubleshoot production problems to improve cheese quality. This approach can be extended using quantitative analysis, which enables further comparisons between structural features and functional measures used within industry, such as cheese meltability, shreddability, and stretchability, potentially allowing prediction and control of these properties. This review covers advances in the analysis of cheese microstructure, including new techniques, and outlines how these can be applied to understand and improve cheese manufacture.

Seasonal variations in the functional performance of industrial low-moisture part-skim mozzarella over a 1.5-year period

Seventy-five blocks of low-moisture part-skim mozzarella cheese were procured from an industrial cheese plant, and the relationships between the physicochemical and functional properties were evaluated during refrigerated storage. In total, cheeses were obtained from 1 cheese vat on 7 different production dates, at 2 to 4 monthly intervals, over a 1.5-yr period; all cheeses were made using a standard recipe. The cheeses were held at 4°C for 0, 1, 2, 4, 8, 16, or 32 d and assayed for composition, primary proteolysis, serum distribution, texture profile analysis, heat-induced changes in viscoelastic behavior, cheese extensibility, and melt characteristics. The results demonstrated a substantial increase in serum uptake by the calcium-phosphate para-casein matrix between 1 and 16 d of storage with a concomitant improvement in the functional performance of the cheese. Extending the storage time to 32 d resulted in further changes in the functional quality, concurrent with ongoing increases in protein hydration and primary proteolysis. Differences in the measured characteristics between the cheeses obtained on different sampling occasions were evident. Principal component analysis separated the cheeses based on their variance in functional performance, which was found to be correlated mainly with the calcium content of the cheese. The results indicate that the manufacturing process should be tightly controlled to minimize variation in calcium content and enhance the quality consistency of the cheese.

Freezing as a solution to preserve the quality of dairy products: the case of milk, curds and cheese

When thinking of the freezing process in dairy, products consumed in frozen state, such as ice creams come to mind. However, freezing is also considered a viable solutions for many other dairy products, due to increasing interest to reduce food waste and to create more robust supply chains. Freezing is a solution to production seasonality, or to extend the market reach for high-value products with otherwise short shelf life. This review focuses on the physical and chemical changes occurring during freezing of milk, curds and cheeses, critical to maintaining quality of the final product. However, freezing is energy consuming, and therefore the process needs to be optimized to maintain product's quality and reduce its environmental footprint. Furthermore, the processing steps leading to the freezing stage may require some changes compared to traditional, fresh products. Unwanted reactions occur at low water activity, and during modifications such as ice crystals growth and recrystallization. These events cause major physical destabilizations of the proteins due to cryoconcentration, including modification of the colloidal-soluble equilibrium. The presence of residual proteases and lipases also cause important modifications to the texture and flavor of the frozen dairy product.