Textural and Rheological Properties of Processed Cheese

Abstract

Cheddar cheeses made from ultra filtered (UF) as well as vacuum condensed milks (CM) containing two protein levels (4.5 and 6.0%) were used to manufacture processed cheeses. These processed cheeses were evaluated for instrumental textural profile analysis (TPA), stress relaxation characteristics using Sintech universal testing machine, and visco elastic characteristics (Elastic modulus-G′ and viscous modulus-G′′) using a Haake Viscometer. A small amplitude oscillatory shear test was employed to assess the visco elastic characteristics. Peleg model and six elements Maxwell model were used to assess stress relaxation characteristics of the cheese. Results indicated that the instrumental TPA hardness of UF2 cheeses made from high protein UF milk was highest (149 N) as compared to cheeses made from low protein UF milk (125 N), high and low protein vacuum condensed milks (103 and 62 N, respectively), and control (53 N). The values of elastic and viscous moduli of cheeses made utilizing high protein UF milk were 3.53 and 2.32 MPa respectively, which indicated its higher viscoelastic nature. The UF2 cheese also showed higher values of modulus of elasticity during stress relaxation (21.8 and 16.2 kPa respectively for Peleg and Maxwell models) and required longer time to relax the given amount of stress as compared to rest of the cheeses. The higher values of hardness and visco-elasticity were attributed to higher protein and lower fat contents in the cheeses. The methods of instrumental texture and rheology evaluation had common outcome for hardness and visco-elasticity of cheeses. Results of stress relaxation tests were more useful to differentiate the cheese characteristics as compared to the results of instrumental TPA and dynamic rheology tests.