Effect of intact casein, total calcium, andpH on the functional properties and microstructure of process cheese

Intact casein (IC), total calcium (Ca) and pH are important physicochemical properties that influence the functional properties of process cheese. The main objectives of the present study were to evaluate the combined effect of IC, Ca, and pH on the manufacturing as well as functional properties of process cheese and to quantify the magnitude by which each of the above indicated physicochemical properties influence the functional properties of process cheese. Two sets of 27 process cheese foods (PCF) were manufactured utilizing all combinations of three factors: IC, Ca, and pH at three levels each (54 PCF total). The three levels of IC were 14, 16, and 18 respectively. The three levels of Ca were 0.45, 0.55, and 0.65% respectively. The three levels of pH were 5.5, 5.8, and 6.1 respectively. All 54 PCF (from both the sets) were also standardized for the same values of moisture (43%), fat (28%), and total protein (21%). All the PCF were evaluated for their manufacturing (end apparent viscosity) as well as functional properties (Texture profile analysis (TPA)-hardness and Rapid Visco Analyzer (RVA)-hot apparent viscosity). Multiple linear regression models were developed to evaluate the nature and magnitude of the effect of IC, Ca, and pH on the PCF manufacturing and functional properties. The pH significantly (P < 0.05) influenced all three properties (end apparent viscosity, TPA-hardness, and RVA-hot apparent viscosity). Ca significantly (P < 0.05) affected the end apparent viscosity as well as the RVA-hot apparent viscosity of the PCF, whereas, the IC significantly (P < 0.05) influenced the RVA-hot apparent viscosity of PCF. Additionally, there was a significant (P < 0.05) interaction effect of IC and Ca and IC and pH on the end apparent viscosity and TPA-hardness of the PCF respectively. The R2 values of the three equations defining end apparent viscosity, TPA-hardness, and RVA-hot apparent viscosity of the PCF were 0.91, 0.93, and 0.77 respectively indicating that statistically robust models describing the nature and magnitude by which IC, Ca, and pH influence the manufacturing as well as functional properties of process cheese were successfully developed.