Frozen storage negatively impacts texture of Monterey Jack caprine milk cheese.

There is a demand for a consistent year-round supply of caprine milk products, but the dairy goat industry is limited by seasonal milk production. With this in mind, USDA-ARS scientists and colleagues from Fort Valley (Georgia) State University evaluated the impact of extended frozen storage on the rheological and proteolytic properties of semi-hard Monterey Jack caprine milk cheese. They wanted to determine the potential for extending the product's marketability.

Milk from Fort Valley State University's dairy goat herd was used to process Monterey Jack cheese. Cheeses were aged at 4 C for six weeks before they underwent four storage treatments: unfrozen fresh control (UFC); frozen-thawed control (FTC) stored at -20 C for two days; and 3 months frozen (MF) and 6 MF, stored at -20 C for three months and six months.

The researchers created protein profiles. They determined rheological properties using texture profile, torsion and small-amplitude oscillatory shear analyses. The scientists found that very little proteolysis occurred in Monterey Jack cheese during frozen storage. But changes did occur in the product's rheological properties. The UFC and FTC cheeses had similar viscoelastic properties, while long-term frozen storage resulted in higher elastic and viscous moduli in the 3-MF and 6-MF cheeses.

As the length of frozen storage increased, the shear stress and strain at the point of fracture of the cheeses decreased. This suggested that the formation of the ice crystals, not proteolysis, altered the macrostructure of the cheese matrix. Although other quality factors must be considered, freezing Monterey Jack caprine milk cheese may not be desirable because of the decrease in the textural quality of the cheese that occurs.

Further information. Diane Van Hekken, Ph. D, Dairy Processing and Products Research Unit, USDA-ARS, Eastern Regional Research Center, 600 East Mermaid Lane, Wyndmoor, PA 19038; phone: [phone]; fax: [phone]; email: [e-mail].