Fine-Tuning Cheese PerformanceFine-Tuning Cheese Performance

Fine-Tuning Cheese Performance

By Kimberlee J. Burrington
Contributing Editor

For those of us who love cheese, it canadd almost as many benefits to a food application as there are cheese varieties.Think of your favorite pizza with the slightly toasted color, buttery flavor,chewy texture and stretch of the mozzarella cheese still warm from the oven. Alfredo sauce would just be white sauce without the textureand flavor of Parmesan cheese. Fried cheese curds without the right meltcharacteristics would just be an empty fried shell. These are just a few of the applications that use the uniquefunctionalities, like meltability, shredability, sliceability, stretch, browningand flavor, that can be built into either a natural or process cheese product.

Cheese technology basics

Inbasic terms, cheese making is a concentration process. But it is far more thanjust a means to remove water from milk and concentrate the casein and fat. Theskilled hands of cheese-makers bring a tremendous diversity in how cheeses taste,melt, stretch, shred and slice, or whether they are hard, soft, brittle orcrumbly. It is the cheese-making process, mainly acid development by the addedstarter culture and the activity of added or native enzymes, as well asmicroorganisms, that create these characteristics.

Cheese making begins by the coagulation of the casein, themain protein in milk. Most varieties of cheese use rennet to clot the milk,but some cheeses use heat and acid (ricotta) or just acid (cottage cheese).Water, or serum, and fat are trapped in the developing mesh or network ofcasein. After the coagulum, or curd, is formed, it is cut into small pieces andthe casein network tighten and pushes the serum out to form the whey. Heatingand acid development by the starter bacteria greatly facilitate this process.After cheese-makers remove the whey, they eventually salt, then press, the curdsinto compact forms and age the product for a specific period of time to developspecific flavor and body characteristics. Cheese making, or curd manipulation, is a relatively simpleprocess.

However, it involves very complex and precise manipulations ofthe casein molecules in order for a cheese to have the desired physical orfunctional properties demanded by the consumer, especially those who wish to usethe cheese in baking. “Whether a cheese softens, flows or even stretches whenheated, or has a rough mouth-feel, is brittle, or even if it is white ortranslucent after baking, it is all about controlling casein chemistry (theinteractions of casein molecules),” says Mark Johnson, Ph.D., senior researcher, Wisconsin Centerfor Dairy Research, Madison.

The degree to which casein molecules are physically separated(the fat and moisture content of cheese) or prevented from interacting (throughcasein chemistry) determine the desired body — the firmness and smoothness —texture, and physical properties, such as melt and stretch, of the final cheese.Casein chemistry may be manipulated by the cheese-maker through strategic controlover the extent of acid development that is allowed to occur at key steps in themanufacturing process. It involves the loss of calcium from the casein and thepH of the cheese. The calcium loss from the casein increases the flow or melt ofthe cheese, but if the pH is allowed to drop too far the cheese will not flowwhen heated. Also involved is the proteolysis that occurs during the ageingprocess. Proteolysis, the breakdown of the casein molecules into smaller piecescalled peptides, might take weeks to be sufficient to influence the melt, (e.g.,it increases the melt, softens and makes the cheese less chewy and smoother).This is caused by the activity of the rennet, microorganisms and enzymesnaturally present in the milk. There are many ways to modify the functionality of natural cheese through thechemistry just described. Process and product limitations are described in the standardsof identity for natural cheese that can be found in Title 21 of the Code ofFederal Regulations (CFR), Section 133.

Culture effects

Cultures aremultifunctional ingredients in cheese. They metabolize lactose to produce energyand lactic acid, provide flavor development, contribute to cheese texture, aidmilk coagulation, and provide moisture control. In general, mesophilic cultures,like Lactococci startercultures, convert lactose to lactic acid at optimum temperatures from 86°F to90°F. Thermophilic cultures, like Steptococcusthermophilus and Lactobacillussp.

,convert lactose into lactic acid and galactose at optimum temperatures from98.6°F to 112°F. Many thermophiles are unable to metabolize galactose, whichcan later create cheese defects.