Thermo-physical properties of semi-hard cheese made with different fat fractions: Influence of melting point and fat globule size

Modelling of dynamic mastication physics of cheese/casein gels as function of milk-fat distribution and intensity of thermo-mechanical treatment

Pasta filata-style cheese products are among the world's most famous cheese varieties. Thermo-mechanical processing of cheese curd results in stringy, fibrous, and anisotropic structures with pleasing texture attributes. A recent area of research focuses on improving yield during the manufacturing of pasta filata-type cheese products by homogenizing the milk. This process reduces the size of fat droplets, leading to better retention of milk fat during curd plasticization. As this sometimes results in texture deficits, this study aims to investigate the impact of thermo-mechanical processing on curd from homogenized and non-homogenized milk. The hypothesis is that increased thermo-mechanical processing, leading to more anisotropic structural elements, may offset texture deficits caused by homogenization. To assess textural and structural changes due to homogenization and thermo-mechanical processing, mechanical tests including rheology and texture analysis were conducted, along with confocal-laser-scanning microscopy. Additionally, sensory evaluation involving panelists consuming the samples and recording mastication properties such as muscle activity and jaw movement was carried out. Dynamic data modeling was used to derive connections between structure and texture. Results showed that homogenization alone did not yield significant differences between the samples, but plasticization and texturization properties differed significantly. Non-homogenized samples developed a distinct fibrous structure, and muscle activities and jaw movements increased significantly (p < 0.01) with longer thermo-mechanical processing.

Insights into the impact of complex phosphates on acid-induced milk fan gel properties: Texture, rheological, microstructure, and molecular forces

Milk fan cheese, a type of stretched -cheese, presents challenges in its stretch-forming. This study investigated the impacts of complex phosphates (sodium tripolyphosphate and sodium dihydrogen phosphate, STPP-DSP) on the gelling properties of acid-induced milk fan gel and the mechanisms contributing to its stretch-forming. The treatment of milk fan gel with STPP-DSP resulted in improved functional and textural properties compared with the control group. In particular, drawing length increased significantly from 69.67 nm to 80.33 nm, and adhesiveness increased from 1737.89 g/mm to 1969.79 g/mm. The addition of STPP-DSP also led to increased viscosity, elastic modulus (G'), and viscous modulus (G"). Microstructural analysis revealed the formation of a fibrous structure within the gel after STPP-DSP treatment, facilitating uniform embedding of fat globules and emulsification. Structural analysis showed that the addition of STPP-DSP increased β-fold and decreased random coiling of the gel, facilitating the unfolding of protein structures. Additionally, UV absorption spectroscopy and excitation-emission matrix spectroscopy results indicated the formation of a chelate between STPP-DSP and milk fan gel, increasing protein-protein molecular interactions. Evidence from differential scanning calorimetry and x-ray diffraction demonstrated the formation of sodium caseinate chelate. Fourier transform infrared spectroscopy and zeta potential analysis revealed that the sodium caseinate chelate formed through hydrophobicity, hydrogen bonding, and electrostatic forces. These findings provided theoretical insights into how phosphates can improve the stretch-forming of milk fan gel, facilitating the application of phosphate additives in stretched -cheese processing.

Changes of physicochemical and functional properties of processed cheese made with natural cheddar and mozzarella cheeses during refrigerated storage

The present study aimed to investigate changes of physicochemical and functional properties of the processed cheeses (PCs) made with Cheddar (PC1), Mozzarella (PC2) and both of them at a ratio of 1:1 (PC3) during storage at 4 °C for 4 months. The results showed that the type of natural cheese used affected the composition of PCs with lower fat content in PC2 due to the lower fat content of Mozzarella cheese used. PC2 with lower fat content showed decreased meltability and oil leakage compared with PC1 and PC3. The stretchability of all the samples significantly (P < 0.05) decreased during storage, and PC1 showed lower stretchability. This was confirmed by increased protein hydrolysis of all the samples during the storage with a higher level of proteolysis in PC1, leading to decreased stretchability of PCs. Further low-field nuclear magnetic resonance analysis indicated more entrapped water in cheese due to moisture migration into the cheese matrix that might squeeze the fat globules to aggregate, causing more fat leakage during later stages of storage. This was evidenced by microstructural analysis showing different extents of increase in fat particle sizes and decrease in free serum in all the PC samples over the storage time. Therefore, the present study provides further understanding of the mechanism of quality change of PC during refrigerated storage as affected by proteolytic properties and composition of natural cheese used.

Effect of Moderate Electric Fields on the Physical and Chemical Characteristics of Cheese Emulsions

Cheese powder is a multifunctional ingredient that is produced by spray drying a hot cheese emulsion called cheese feed. Feed stability is achieved by manipulating calcium equilibrium using emulsifying salts. However, the increased demand for 'green' products created a need for alternative production methods. Therefore, this study investigated the impact of ohmic heating (OH) on Cheddar cheese, mineral balance, and the resulting cheese feed characteristics compared with a conventional method. A full factorial design was implemented to determine the optimal OH parameters for calcium solubilization. Electric field exposure and temperature had a positive correlation with mineral solubilization, where temperature had the greatest impact. Structural differences in pre-treated cheeses (TC) were analyzed using thermorheological and microscopic techniques. Obtained feeds were analyzed for particle size, stability, and viscosity. OH-treatment caused a weaker cheese structure, indicating the potential removal of calcium phosphate complexes. Lower component retention of OH_TC was attributed to the electroporation effect of OH treatment. Microscopic images revealed structural changes, with OH_TC displaying a more porous structure. Depending on the pre-treatment method, component recovery, viscosity, particle size distribution, and colloidal stability of the obtained feeds showed differences. Our findings show the potential of OH in mineral solubilization; however, further improvements are needed for industrial application.

Effect of Process and Formulation Variables on the Structural and Physical Properties in Cream Cheese using GDL Acidulant

We report on the properties of analogue cream cheeses prepared using glucono delta-lactone (GDL) acidulant, notably the impact of particular processing and formulation variables, (homogenisation pressure, coagulation pH and temperature, and stabiliser level) on cream cheese physical, material and microstructural properties. Protein–protein and protein-fat interactions were seen to be the primary structural contributors to the physical properties of cream cheese. Cream cheese microstructure and its properties demonstrated well-defined correlations to specific and controllable processing elements within the manufacturing process, showing significance in interactions between parameters in multivariable linear regression analysis (P < 0.05). Summarising the effect of processing variables on key cheese properties, we observed that a progressive reduction in fat particle size of cheese milk arising from increasing homogenisation pressures was seen to increase the total surface area of fat that could be incorporated into the curd during coagulation. The greater extent of fat-fat and fat-proteins interactions during coagulation provided a reinforcing effect on the microstructure of the final cream cheese, with a corresponding increase in compressive fracture stress, shear storage modulus (G′) and shear loss modulus (G″). In terms of other processing variables, cream cheese firmness was also observed to progressively increase through lowering of coagulation pH from 5.13 to 4.33. Increasing coagulation temperature from 58 °C to 78 °C similarly caused an increase in cheese firmness. Finally, increasing the levels of added stabiliser were shown to correlate with increasing cheese firmness. Similar correlations could be observed in relation to physical properties, notably forced expressible serum separation. This model cream cheese preparation method has provided a useful model system for relating food structure to material and functional properties. In addition, it has the advantage of being able to rapidly screen many formulation and process variables because it is faster than the traditional cheesemaking. This study showed that the adjustment of process and formulation variables, either in isolation or in combination, in the manufacture of cream cheese can significantly influence the final material and textural properties of the product, thereby enabling controllable functional attributes capable of meeting different customer needs.

Effect of Packaging and Portioning on the Dynamics of Water–Fat Serum Release from Fresh Pasta Filata Soft Cheese

The aim of the present study was to analyze the impact of cheese fragmentation and packaging on the dynamics of water–fat serum released from pasta filata cheese made from cow’s milk and its mixture with sheep’s milk. The addition of sheep’s milk reduced the amount of leachate from the vacuum-packed cheeses and did not cause as much loss of gloss as in the case of cow’s milk cheeses. This was also reflected in the microscopic images of the cheese samples. Consumers showed less acceptance of cow’s milk pasta filata cheeses than cheeses made with a mixture of cow’s and sheep’s milk (they had the same fat content, acidity, hardness, and oiling-off, but better stretching). The data describing water–fat serum release from pasta filata cheese within 24 h of unpacking was modeled with the use of the feed-forward artificial neural networks, whose architecture is based on Multi-Layer Perceptron with a single hidden layer. The model inputs comprised four independent variables, including one quantitative (i.e., time) and the other qualitative ones, which had the following states: type of raw material (cow’s milk, cow-sheep’s milk), way of sample portioning (whole, quarters, slices), packing method (vacuum packed and packed in brine).

Effect of Water Temperature and Time during Heating on Mass Loss and Rheology of Cheese Curds

During the manufacturing of mozzarella, cheese curds are heated to the desired stretching temperature traditionally by immersion in water, which influences the curd characteristics before stretching, and consequently the final cheese properties. In this study, cheese curds were immersed in hot water at 60, 70, 80 and 90 °C up to 16 min and the kinetics of mass loss and changes of rheological properties were investigated. The total mass of cooked curds increased up to 10% during the first minute, independent of the temperature, as a consequence of water retention. Fat was the main component lost into the cooking water (<3.5% w/w), while the concentration of protein increased up to 3.4% (w/w) compared to uncooked curds due to the loss of other components. Curds macrostructure during cooking showed that curds fully fuse at 70 °C/4 min; 80 °C/2 min and 90 °C/1 min, while after intensive cooking (>8 min) they lost the ability to fuse as a consequence of protein contraction and fat loss. Storage modulus, representing the curd strength, was dependent on cooking temperature and positively, and linearly, correlated with curd protein content (21.7–24.9%). This work shows the potential to modify curd composition and structure, which will have consequences for further processing and final product properties.

The Effect of Freezing Sheep's Milk on the Meltability, Texture, Melting and Fat Crystallization Profiles of Fresh Pasta Filata Cheese

Simple Summary

Sheep’s milk is usually produced on small farms. It is mainly used in the pro duction of cheese products. One of the methods of extending the shelf life of sheep’s milk is freezing it. In this study we examined the effect of freezing on sheep’s milk and a mixture of sheep’s and cow’s milk on the quality of fresh pasta filata cheeses produced from the milk. It has been proven that the freezing of milk affects the possibility of using it in later cheese processing. Freezing sheep’s milk influenced, among others, a greater hardness and less elasticity of the cheese. We also noticed that the addition of frozen sheep’s milk caused consumer dissatisfaction.

Abstract

Sheep’s milk is produced in smallholdings, which hinders the continuity of production. Therefore, freezing during periods of high production can be a solution. Herein, we examined the effect of freezing on sheep’s milk and a mixture of sheep and cow’s milk (70:30, v/v) on the quality of fresh pasta filata cheeses produced from the milk. Frozen/thawed sheep’s milk contributes little to the development of innovative and reformulated cheeses. This was due to 24% higher hardness and greater extensibility and cutting force, as well as lower stretching and elasticity. Although their flowability increased (Oiling-off from 3 to 12%), the meltability (tube test, and Schreiber test) decreased. Additionally, the use of frozen milk caused consumer dissatisfaction. The consumer penalty analysis of the just–about–right showed that freezing of the milk caused the loss of the refreshing, elasticity and shininess of pasta filata cheeses.

The state of water and fat during the maturation of Cheddar cheese

Cheddar cheese predicted to develop into different quality classes has been evaluated by time domain Nuclear Magnetic Resonance, Thermogravimetric analysis and quantitative sensory analysis. The water and fat proton signals in the transverse relaxation decay curves have been deconvoluted. Proton transverse relaxation values for both the water and fat fractions decrease and the relative %age of the proton peak area, predominantly from the fat increases over a 450-day ripening period. The thermodynamic free water percentage increases during maturation. Water and fat attributes can distinguish between Cheddar cheese batches after 56 days. Cheese batches which have lower transverse relaxation values for the water and fat proton fractions and a higher relative %age of the proton peak area predominantly from fat at 56 days, mature after 270 days to be more yellow, rubbery and smooth, have a less sour and lingering aftertaste and are also harder to form into a cheese ball.