Relationships among rheological, sensory, and wear behaviors of cheeses

Studying rheological and sensory behaviors of cheese provides structural and texture-related information that could be useful for a better understanding of the complex wear behaviors of cheese and their relationships with cheese industrial and oral processing behaviors. Thus, the objective of this study was to determine the relationships of rheological and sensory properties with cheese wear. Rheological tests including large amplitude oscillatory shear, strain sweeps at different temperatures (5, 15, and 25°C), and large-strain compression at room temperature (22 ± 2°C) were conducted for cheeses with varying fat contents (40, 50, 52, and 54% fat-in-dry-matter aged for different periods (15, 30, 45, and 60 d). Descriptive sensory analysis was used to evaluate cheese sensory texture attributes. Overall, fat content, testing temperature, and aging time had significant impact on cheese viscoelastic parameters. Higher temperature, aging time, and fat content led to lower rigidity and greater extent of nonlinear viscoelastic behaviors in the cheeses. Mass loss showed negative correlations with critical strain (γ_c ), critical stress (σ_c ), complex modulus (G^* ), and fracture stress, but had positive correlations with phase angle (δ) and fracture strain. Sensory data showed that texture attributes were affected by cheese fat content and aging time and had significant correlations with mass loss at high normal force and sliding speed. This study showed that rheology and sensory data can be used to provide fundamental information on the wear behaviors of cheese and other soft materials.

A Model System for Studying the Effects of Colloidal Calcium Phosphate Concentration on the Rheological Properties of Cheddar Cheese

A novel model system was developed for studying the effects of colloidal Ca phosphate (CCP) concentration on the rheological properties of Cheddar cheese, independent of proteolysis and any gross compositional variation. Cheddar cheese slices (disks; diameter = 50 mm, thickness = 2 mm) were incubated in synthetic Cheddar cheese aqueous phase solutions for 6 h at 22 degrees C. Control (unincubated) Cheddar cheese had a total Ca and CCP concentration of 2.80 g/100 g of protein and 1.84 g of Ca/100 g of protein, respectively. Increasing the concentration of Ca in the synthetic Cheddar cheese aqueous phase solution incrementally in the range from 1.39 to 8.34 g/L significantly increased the total Ca and CCP concentration of the cheese samples from 2.21 to 4.59 g/100 g of protein and from 1.36 to 2.36 g of Ca/100 g of protein, respectively. Values of storage modulus (index of stiffness) at 70 degrees C increased significantly with increasing concentrations of CCP, but the opposite trend was apparent at 20 degrees C. The maximum in loss tangent (index of meltability/flowability) decreased significantly with increasing concentration of CCP, and there was no significant effect on the temperature at which the maximum in loss tangent occurred (68 to 70 degrees C). Fourier transform mechanical spectroscopy showed the frequency dependence of all of the cheese samples increased with increasing temperature; however, solubilization of CCP increased the frequency dependence of the cheese matrix only in the high temperature region (i.e., >35 degrees C). These results support earlier studies that hypothesized that the concentration of CCP strongly modulates the rheological properties of cheese.

Impact of Modifications in Acid Development on the Insoluble Calcium Content and Rheological Properties of Cheddar Cheese

Cheddar cheese was made from milk concentrated by reverse osmosis (RO) to increase the lactose content or from whole milk. Manufacturing parameters (pH at coagulant addition, whey drainage, and milling) were altered to produce cheeses with different total Ca contents and low pH values (i.e., <5.0) during ripening. The concentration of insoluble (INSOL) Ca in cheese was measured by cheese juice method, buffering by acid-base titration, rheological properties by small amplitude oscillatory rheometry, and melting properties by UW-Melt Profiler. The INSOL Ca content as a percentage of total Ca in all cheeses rapidly decreased during the first week of aging but surprisingly did not decrease below approximately 41% even in cheeses with a very low pH (e.g., approximately 4.7). Insoluble Ca content in cheese was positively correlated (r = 0.79) with cheese pH in both RO and nonRO treatments, reflecting the key role of pH and acid development in altering the extent of solubilization of INSOL Ca. The INSOL Ca content in cheese was positively correlated with the maximum loss tangent value from the rheology test and the degree of flow from the UW-Melt Profiler. When cheeses with pH <5.0 where heated in the rheometer the loss tangent values remained low (<0.5), which coincided with limited meltability of Cheddar cheeses. We believe that this lack of meltability was due to the dominant effects of reduced electrostatic repulsion between casein particles at low pH values (<5.0).