November 4/Guemes, Argentina/Science Letter -- According to recent research from Guemes, Argentina, "The change in the viscoelastic behavior over ripening of a commercial low-fat soft cheese was investigated. Twelve low-fat soft cheeses that contained microparticulated whey proteins as fat mimetics were obtained from a local factory and stored at 6 degrees C. Three of these cheeses were sampled at one, 21, 48 and 76 days of ripening."

"Physicochemical properties such as pH, moisture content, salt concentration and maturation index (MI) were determined. Frequency sweeps were performed in the range of 0.01-10 Hz at 20 degrees C and the region of linear viscoelasticity was determined by performing stress sweeps. Frequency dependence of elastic and viscous moduli was modeled using the power-law and Maxwell equations. The initial moisture content was 52.80 +/- 0.46% and did not change significantly during ripening. Salt concentration on day one was 0.41 +/- 0.01% and increased significantly during maturation. The pH decreased from 5.27 +/- 0.03 on day 1 to 5.11 +/- 0.03 by day 48, while the MI increased from 3.60 +/- 0.67 on day 1 to 8.66 +/- 1.05% by day 48. Low-fat soft cheese containing whey proteins behaved as a linear viscoelastic material during dynamic testing at stresses below 630 Pa. In general, viscoelastic parameters derived from both models decreased with ripening time and at the same kinetic rate, showing that ripening contributed to changes in the structure of the cheese matrix," wrote B.E. Meza and colleagues.

The researchers concluded, "Rheological and physicochemical properties were correlated using one of the parameters derived from the power-law model, and the results indicated that correlations improved when MI was included in the model."

Meza and colleagues published their study in Dairy Science & Technology ("Viscoelastic Behavior During the Ripening of a Commercial Low-fat Soft Cheese." Dairy Science & Technology, 2010;90(5):589-599).

For additional information, contact A.C. Rubiolo, UNL, CONICET, Institute Desarrollo Tecnol Ind Quim INTEC, Guemes 3450, RA-3000 Santa Fe, Argentina.

From the November 29, 2010, Prepared Foods E-dition