71A-37

A. C. BISWAS¹, R. Kapoor², P. Upreti², L. E. Metzger², and K. Muthukumarappan¹. (1) Dept. of Agricultural and Biosystems Engineering, South Dakota State Univ., 1400 North Campus Dr., Box 2120, Brookings, SD 57007-0001, (2) Dept. of Food Science and Nutrition, Univ. of Minnesota, 1334 Eckles Ave., 122 Food Science and Nutrition Bldg., Saint Paul, MN 55108-1038

Process cheese is a viscoelastic material with unique elastic and viscous properties. These properties may influence the functionality of process cheese when used in different food applications. We hypothesize that different levels of buffer, residual lactose, and salt-to-moisture ratio can alter the viscoelastic properties of process cheese. The objective of this study was to investigate the influence of two different levels (high and low) of buffer (calcium and phosphorous), two levels (high and low) of residual lactose, and two levels (high and low) of salt-to-moisture (S/M) ratio on viscoelastic properties of eight different process cheeses. Eight different treatments of process cheese were prepared from natural Cheddar cheese. Stress sweep to determine linear viscoelastic region (about 750 Pa max. shear stress), and frequency sweep (0.1 Hz to 200 Hz) tests were performed on experimental samples. The data obtained was best fitted in power-law model, and parameters such as "a" and "c" were determined. Significant difference (P < 0.05) was observed in low frequency storage and loss modulus ("a" and "c" respectively) between the buffer and salt content (high and low) in process cheese. No significant differences were observed (P > 0.05) for "a" and "c" values with residual lactose content (high and low) in the process cheese samples. Six-element Kelvin-Voigt model was used to predict the creep compliance data for eight different process cheeses. Instantaneous slope of the creep curve was defined as the viscoelasticity index. It was observed that buffer (high/low) and S/M ratio (high/low) content had significant effects on viscoelastic parameters. The results could be employed for better understanding the treatments used to improve the casein micelle structure in process cheese, and also the producers can control cheese functionality during manufacturing.

Session 71A, Dairy Foods: General
8:30 AM - 12:00 PM, Tuesday AM Room Hall I-2

2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana