Importance of relationships among cheese properties.

Recent studies of reduced- and full-fat mozzarella cheese confirm that the relationship among the fat content, salt concentration and age of the cheese during its storage plays a critical role in determining the degree of whiteness that this cheese reflects. Background for this research stems from a color-appearance defect specific to reduced-fat mozzarella. When made with either a 10% or 6% fat content, mozzarella has a greenish tint. This lower-fat mozzarella cheese also decreases in whiteness during storage, and if no colloidal or particulate colorants are added to compensate for the absence of fat globules, the cheese can become translucent.

Apparently, cheeses containing a higher level of fat (greater than 10%) retain their opacity, presumably because the fat globules scatter light. Based on light refraction evaluations conducted at Utah State University (Logan, UT), cheeses of varying fat contents reach the same level of opacity as shown by their L-values. When baked on pizza, the nonfat cheese actually demonstrates an opaqueness similar to regular low-moisture part-skim mozzarella. But it loses this opacity when it cools and takes on a glassy appearance. Cheesemakers should consider the action of casein molecules during these environmental changes. During heating, casein will aggregate into dense clusters, dispersing light and giving cheese a white appearance.

Upon cooling, the casein aggregates rearrange into less dense aggregates and do not disperse light. Without fat to disperse light, the cheese appears translucent or glassy. Similarly, when cheese is high in salt or low in pH, caseins will aggregate into dense clusters and appear white regardless of the temperature and fat content. More work is necessary to understand the variables that could help low-fat and non-fat mozzarella cheese achieve the functional performance even closer to that of regular-fat mozzarella cheese.

For many varieties of cheeses, the development of flavor is due to myriad enzymatic and chemical reactions, as well as the microbiological metabolism of the casein, fat, citric acid and lactose from lactic acid in the cheese. The complexity of flavor development and the lack of knowledge regarding the combination of specific flavor components that produce desired flavors have always challenged cheesemakers who want to reliably reproduce high-quality cheese on a consistent basis.

Cheese processors and suppliers that recognize the science behind the development of flavor can make better decisions about how to control and potentially enhance flavor development in specific cheeses. In addition to selecting a starter, starter adjunct cultures and other added microorganisms and enzymes, the cheesemaker must be cognizant of other parameters. These parameters include milk quality (bacteriological and enzymatic); heat treatments; cheese composition; processing techniques such as whey dilution and curd rinsing; ripening temperature; and acid development.

Current research at the University of Wisconsin and Utah State University aims to better understand the development of bitterness and the role of the starter. Other research will focus on the potential to control the development of specific flavor components by bacterial contaminants and specifically added microorganisms.

Further information. Amy Skovsende, Dairy Management Inc., 10255 W. Higgins Rd., Suite 900, Rosemont, IL 60018. Phone: [phone]. Fax: [phone]. URL: http://www.extraordinarydairy.com.