A Cheese to Please Any Palate

Most cheeses list only four ingredients on the label: cultures, enzymes, milkor a derivation ofand salt. Yet those four ingredients can form an array of natural cheeses with profiles ranging from hard to soft, smooth to crumbly, sharp to mellow, and plain to piquant. More than 1,400 natural cheese varieties are cataloged in the World Cheese Exchange Database, and around two-thirds contain only those four ingredients.

The secret to variety lies with highly selective ingredient choices. Processing also plays a major role in creating a signature cheese. Most cheese manufacturers use the same basic processing steps; however, no two varieties are produced by exactly the same method.

Cheesemaking basics

The principle of cheese-making is the same for all natural cheeses: extract the water from milk, leaving behind solids in the form of curd. Basically, cheese consists of the milk protein casein (whey proteins do not form curdmost are washed away with the water); nearly all of the fat present in the milk, as well as the fat-soluble vitamins; minerals, such as calcium; and entrapped water. The entrapped water contains the water-soluble constituents, such as lactose, some whey proteins, soluble salts, vitamins and other minor components.

Casein forms curd through coagulation, a precipitation of solids that occurs in the presence of acid produced by starter cultures and/ or coagulating enzymes. Milk can also be acidified by food-grade acidulants, a process often used in fresh cheese manufacture.

A cheeses flavor and aroma directly results from its protein and fat content, and is modified or enhanced by adding starter or adjunct (nonacid-producing) cultures and enzymes, as well as the occasional bacteria, mold or yeast. Ripening, or aging, and specific manufacturing procedures such as curd-washing and salting all affect flavor. Some specialty cheeses include identifying flavoring ingredients such as garlic, jalapeño peppers or port wine.

Milk drives flavor

Milk is the predominant ingredient in cheese, and almost all U.S. cheese is manufactured from some form of cows milk (whole, low-fat, nonfat, buttermilk, cream, whey, yogurt, nonfat dry milk, or a combination). Other animal milks (goat and sheep) are also successfully used, either alone or in combination with cows milk. Plus, vegetarian cheese-like products use the liquid extracted from crops such as rice and soybean; however, federal standards of identity prevent these analogs from being labeled cheese. Title 21, Part 133 of the Code of Federal Regulations provides definitions and specifications for general cheese terms, as well as for some specific varieties.

With cheese basically being a type of milk concentrate, milk quality and flavor impact its sensory attributes. The breed of animal, its age, its feed, its hygiene, the soil and even the weather directly impact milk quality and flavor.

In the olden days, cheese-makers would simply smell and taste the milk, and if it did not pass their discriminating taste buds, it was not made into cheese, says Scott Rankin, associate professor of food science, University of Wisconsin-Madison, and a scientist at the co-located Wisconsin Center for Dairy Research (WCDR). Today, quality tests are more sophisticated, with results quantified. But more often than not, cheese-makers still do the smell and taste test as part of the quality assurance process. The cows diet has a real impact on milk flavor, which ultimately transfers to the cheese.

Today, there is a trend toward cheeses with flavor profiles associated with pasture- and grass-fed cows, as environmentalists view these cows as treated more humanely.

The grassy flavor profile has long been associated with cheeses made from milk from Australian and New Zealand cows, where herds only graze in open pastures, says Mary Anne Drake, associate professor of food science, North Carolina State University (NCSU), Raleigh, NC, and a scientist at the Southeast Dairy Foods Research Center (SDFRC) at NCSU. Americans traditionally shunned this grassy flavor, but there has been resurgence in the popularity of this flavor profile.

Grass Point Farms, Thorp, WI, is marketing a line of cheeses made from pasture-raised cows milk. Referred to as terroir cheeses, a French term that means sense of place, the greatest influence on terroir cheese comes from the animal from which milk is obtained. For us, a terroir cheese is whats created when geography, climate, soil and animals work together to produce the quality and taste of our milk, says Chad Pawlak, president.

A cows diet also influences milk composition, particularly milk-fat profiles, Rankin says. For example, when cows graze on certain grasses, the milk can contain higher levels of conjugated linoleic acid, a fatty acid recognized as possessing numerous health benefits.

Dean Sommer, cheese and food technologist, WCDR, says: Cows fed a diet high in flaxseed produce milk with high levels of omega-3 fatty acids, which are considered heart-healthy. Flaxseed affects milks flavor, and some of that is transferred into cheese. However, consumers looking for ways to increase their dietary intake of omega-3s might find this flavor desirable. . . sort of reassuring that they are getting a dose of omega-3.

Milk quality, in terms of microbial load, also influences flavor. Theoretically, milk has a very low or no microbial load when it leaves the cow, but almost instantly is exposed to a plethora of microorganisms that find the nutrient-dense, neutral-pH fluid system the ideal growth medium. These microorganisms are present on the inside and the outside of the cows teats, on the udder and even on the hide. More microbes can be picked up from the milking equipment and the people handling it. If these grow, milk flavor soon goes off.

U.S. farmstead cheese operations produce unique cheeses with signature flavor profiles. As soon as the cows are milked, their milk is transported directly to the cheese vat, instead of held in refrigerated storage tanks. The milk from our own cows on our dairy farm is what is used to make our cheese unique, says Lynn Giacomini Stray, managing partner, Point Reyes Farmstead Cheese Co., Point Reyes Station, CA. Our Original Blue cannot be duplicated, even fives miles away.

Most large-volume cheese-making operations are not located near where the milk is procured. Thus, the milk must be cooled at the dairy farm and transported in refrigerated tankers. Improperly cooled milk soon goes sour, due to acid production by lactobacilli. Even if refrigerated, raw milk goes off due to psychrophilic (cold-tolerant) bacteria, which produce proteinases and lipases, breaking down protein and fat and causing rancid and bitter tastes. When an animal suffers from mastitis, milk can contain bacteria in vivo, including certain Escherichia coli, for instance.

Almost all milk made into cheese in the United States is pasteurized for safety. Pasteurization is not a substitute for sanitation; in fact, it does not destroy all microorganisms. It does kill all pathogenic ones, and it destroys many undesirable gas- and flavor-forming microorganisms, but these continue to grow over time, even at refrigerated temperatures. Unfortunately, pasteurization also kills milks inherent enzymes, which contribute to cheese flavor development.

Best results come from milk with low inherent microbial counts at the time of milking, as pasteurization doesnt destroy foul-tasting substances produced by bacterial breakdown of protein and fat. Because bacterial counts can increase during raw-milk storage, it should have low counts at the time of cheese-making. In general, colony counts less than 200,000 per ml of milk have no impact on cheese quality. Above that, quality is jeopardized. If bacterial counts exceed 100 million, the raw milk is generally unsuitable for cheese-making.

Microbe management

The disadvantage of pasteurization is the difficulty of developing the full typical flavor in some cheeses, says Rankin. For example, Hispanic fresh cheeses made in the United States pale in comparison to their countries of origin, where these fresh cheeses are made using local raw milk supplies loaded with native flavor-producing, heat-labile compounds, he says.

By understanding how and when enzymes and cultures produce flavor, we can selectively add microorganisms either natural flora or adjunctsand enzymes back into the cheese milk after pasteurization, says Sommer. We can produce great-tasting table cheese, which is what we call the packaged product consumers buy at retail, as well as intensely flavored ingredient cheese.

Sans fat

Mark Johnson, senior scientist, WCDR, has been working with developing specific flavor attributes in zero-fat ingredient cheeses. These cheeses do not need to be palatable as is, but must deliver consistent cheese flavors in an application, he says. In fact, sometimes we use cultures and enzymes not traditionally used in a specific cheese variety to create a flavor profile that, when used in a specific application, say a baked cheese cracker, the right cheese flavors come through.

For example, about 30 years ago, scientists identified Lactococcus lactis subsp. cremoris as the preferred bacterium for Cheddar cheese. More recently, Lc. cremoris has been recommended for lowfat and fat-free Cheddar-cheese production. However, cheese made with slow acid-producing cultures such as Lc. cremoris tends to ripen slower. To overcome this, adjunct cultures such as Lactobacillus helveticus and Lactobacillus casei can increase flavor and aroma sooner. Brevibacterium linens, typically used for brick and Limburger cheeses, may be used as an adjunct to speed flavor development in reduced-fat and full-fat Cheddar cheeses.

Culturing flavor development

The biological changes that occur in the carbohydrate, fat and protein in cheese impact cheese flavor, and these changes are manipulated through the addition of starter and adjunct cultures, and enzymes. Processing can be adjusted to slow or speed the rate of culture and enzymatic activity, with activity impacting the type and rate of flavor development.

The primary carbohydrate in cheese, lactose, is a disaccharide that is fermented by starter cultures to lactic acid at different rates during cheesemaking. This affects cheese pH, which is related to chemical changes in the cheeses protein network. In addition, fermentation of lactic acid and other minor carbohydrates, such as citrate, play an important role in developing flavor of some cheese varieties.

During the ripening step, casein is hydrolyzed, releasing peptides and amino acids into the cheese mass. These contribute directly to cheese flavor, and act as precursors of other flavor compounds. Protein-derived compounds contribute desirable sweet, sulfur or heat-treated flavor notes. However, they are also responsible for undesirable bitter, unclean or brothy notes. In general, the more ripened or aged the cheese, the more flavorful it is.

There is a direct relationship between the percent of specific free water-extractable amino acids and the flavor intensity. For example, when hard cheeses such as Cheddar and Swiss ripen, insoluble casein is progressively converted to simpler, moresoluble nitrogenous compounds until about 30% of the casein converts into a water-soluble form. In soft, ripened cheeses like Brie, a greater proportion, as much as 50%, is converted into soluble forms, which contributes to the soft texture. In these varieties, as compared to hard ripened, amino acids are liberated from protein more rapidly, and a greater percent of ammonia is released. This contributes to the overall flavor profile.

Also during ripening, the fat of some cheese is hydrolyzed by lipolytic enzymes, liberating free fatty acids that play an important role in the distinctive flavor of different cheese. Lipolysis occurs to the greatest extent in semi-soft cheese, particularly blue types.

Enzymes also release the volatile fatty acidsbutyric, caproic, caprylic and capricfrom fat. Some of these oxidize during ripening, forming compounds that contribute to the flavor of a specific cheese variety.

Lexicon language

Increased consumer interest in the many cheese varieties has fueled demand for science-based knowledge about cheese flavor and the sensory factors that drive preferences. To help standardize and improve cheese quality, industry needs a common language to define and describe critical cheese characteristics.

Linking cheese flavor research to production technology is the key to helping the food industry master and control the factors that influence cheese flavor, says Drake. Our challenge was to integrate precise analytical measurement tools with the psychology and communication of language descriptors.

Drake and co-workers, funded in part by dairy farmers through Dairy Management Inc., Rosemont, IL, have successfully used this approach to compile a comprehensive descriptive sensory language for Cheddar-cheese flavor. This language has also been instrumental in defining several Italian cheeses.

The language resource, known as the cheese lexicon, was generated from the analysis of 220 Cheddar cheeses and 70 other cheeses representing age, fat content and geographical regions. Trained panelists helped establish the language of qualitative and quantitative terms, each with intensity anchors and specific references for its flavor definition, says Drake. Flavor terminology like fruity, diacetyl and earthy were tied to specific esters, microflora and aromatics establishing many corresponding concentration and intensity relationships. The lexicon can help characterize products and improve quality by measuring and controlling the presence of those chemical compounds associated with flavor defects, adds Drake.

Kathleen Rutledge, president and CEO, 21st Sensory Inc., Bartlesville, OK, says: While training a group of new descriptive panelists, I asked them to begin to develop a lexicon for the cheese flavor in a macaroni and cheese application. We started by identifying dairy terms such as milky, casein, diacetyl and butter. When they began to describe the cultured dairy flavors, the group was clearly polarized. Half of the group noted that one product was very cheesy, while the other half of the group had the opposite opinion. She polled the group on the types of cheeses they consumed and found the group that rated macaroni and cheese as very cheesy were accustomed to processed American cheese. The other panelists typically ate aged cheeses. What followed was an extensive orientation to the world of cheese, to align the panelists concepts on what constituted the range of cheese flavors.

Sensory work enables cheese ingredient suppliers to blend just the right amount of specific cheeses with select flavors to produce an ingredient that delivers the profile promised. For example, Kraft Food Ingredients Corp. (KFIC), Memphis, TN, has developed Grated Asiago, Parmesan and Romano Cheese Blend. Since KFIC produces all of its cheeses on-site, we were able to create a cost-effective, natural blend of these three cheeses that doesnt sacrifice the distinctive, pungent Asiago flavor profile, says Mary Taylor, business marketing manager, Italian-style cheeses.

Just four ingredients . . . but the flavor profiles are infinite.

Donna berry, president of Chicago-based Dairy & Food Communications, Inc., a network of professionals in business- to-business technical and trade communications, has been writing about product development and marketing for years. Prior to that, she worked for Kraft Foods in the natural-cheese division. She has a B.S. in Food Science from the University of Illinois in Urbana-Champaign. She can be reached at [email protected].