October 22/Science Letter -- According to a study from the U.S., "This study investigated the effects of aging and fat content on the texture of Cheddar cheese, both mechanical and sensory aspects, over a nine-month aging period. Cheeses of 6, 16 and 33% fat were tested at 0.5, three, six and nine months of aging."

"Cheeses were evaluated by a trained sensory panel using an established texture lexicon as well as instrumental methods, which were used to probe cheese structure. Sensory analysis showed that low-fat cheeses were differentiated from full-fat cheeses by being more springy and firm, and this difference widened as the cheeses aged. In addition, full-fat cheeses broke down more during chewing than the lower fat cheeses and the degree of breakdown increased with aging.

"Mechanical properties were divided by magnitude of deformation during the test and separated into three ranges: the linear viscoelastic region, the nonlinear region, and fracture point. These regions represent a stress/strain response from low to high magnitude, respectively. Strong relationships between sensory terms and rheological properties determined in the linear (maximum compliance) and nonlinear (critical stress and strain and a nonlinear shape factor) regions were revealed. Some correlations were seen with fracture values, but these were not as high as terms related to the nonlinear region of the cheeses. The correlations pointed to strain-weakening behavior being the critical mechanical property. This was associated with higher fat content cheeses breaking down more as strain increased up to fracture. Increased strain weakening associated with an increase in fat content was attributed to fat producing weak points in the protein network, which became initiation sites for fracture within the structure," wrote N.R. Rogers and colleagues, North Carolina State University.

The researchers concluded, "This suggests that fat replacers need to serve this functional role."

Rogers and colleagues published their study in the Journal of Dairy Science ("The Effect of Aging on Low-fat, Reduced-fat, and Full-fat Cheddar Cheese Texture." Journal of Dairy Science, 2009;92(10):4756-4772).

For more information, contact E.A. Foegeding, North Carolina State University, Dept. of Food Bioproc & Nutrition Science, Raleigh, NC 27695.

From the October 26, 2009, Prepared Foods E-dition