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December 1, 2000
Discovering Dairy Flavors
By Christine Homsey
What does milk taste like? Good question! The flavor of fresh, fluid milk is difficult for many to articulate, yet most find its flavor very pleasant and consume it as the basis for a host of other flavorful dairy products.
Because cow’s milk is very bland, it’s often easier to describe its basic tastes rather than its flavor. Milk leaves several sensations on the tongue, including sweetness from the lactose, saltiness from the inorganic salts and the creaminess or slickness from the milkfat. Other compounds that contribute to milk flavor are alcohols, esters, lactones and heat-induced compounds.
Cow’s milk is the most commonly used substrate throughout the world, but milk products from sheep, goats, camels, buffalo, horses, yaks and zebu (oxen) are frequently consumed outside of the United States. Each species’ milk has its own unique flavor. Goat’s milk, for instance, gets its distinctive flavor from caprylic acid as well as other short-chain fatty acids.
Many chemical compounds are responsible for the distinctive flavor profiles of bovine dairy products. Cream and butter flavors result from diacetyl, free fatty acids (FFAs) and acetaldehyde. Some compounds responsible for cheese flavor include FFAs, sulfur compounds, lactic acid, acetic acid and peptides from the breakdown of proteins. The starter culture used in cheese impacts flavor, and the protein breakdown results in a savory, umami taste. Yogurt derives much of its characteristic flavor from acetaldehyde.
Off-flavors in milk
Because milk has such a delicate flavor, off-flavors are easily detected. According to Ramesh Chandan, Ph.D., president of Global Technologies Inc., St. Paul, MN, three major kinds of off-flavors are associated with dairy ingredients. The first comes from the environment. An off-flavor can originate from the cow’s feed or plant materials grazed on, such as onion or garlic bulbs. Milk is exposed to the barn’s ambient temperature and odors, and if not cooled quickly and stored properly, putrid off-flavors can result.
The second type of off-flavor results from fat hydrolysis, which occurs when the enzyme lipase activates in raw milk during milking or shipment. Lipase can tear apart the milkfat, releasing butyric acid and other short-chain fatty acids that cause undesirable, rancid flavors.
Finally, off-flavors occur by oxidation, an age- or storage-related problem. Translucent plastic jugs can allow a stale, cardboard-like taste to develop that is sometimes referred to as oxidized or "light-struck." Although oxidized flavors are a form of rancidity, they have a different character than the strong, harsh flavors of lipolytic rancidity. Other factors that can cause off-flavors include microbial growth, the animal’s medications, processing conditions and contamination by substances such as chemical sanitizers. Proper handling, treatment and storage will prevent milk from losing its clean taste. Dairy ingredients and products should be kept in tightly sealed containers and should never be stored near strong-smelling foods.
Animals produce natural dairy flavors as a part of their normal metabolic processes; they can be further modified by culturing, cooking or other processing. Basic dairy products, such as milk, butter, cream, sour cream, yogurt and cheese, can impart dairy flavor to foods. Further-processed and concentrated dairy ingredients such as dried milk, dried butter, buttermilk solids, butter oil, dried cheese and enzyme-modified cheeses (EMCs) or butters may also be used. Finally, a dairy flavor can be achieved through the use of a compounded flavor, which may be natural, artificial or both. Flavors come in liquid, paste or powder form. They may be used to impart a certain desirable flavor, boost or modify a flavor already present, or mask an unwanted flavor.
Although dairy ingredients such as fluid milk and natural cheese tend to give very natural, pleasant flavors, they have some disadvantages. They can be very expensive and managing cold inventory can be cumbersome. Sometimes these flavors are so delicate that they don’t impart enough flavor of their own, even at high levels, requiring a boost from a concentrated powder or compounded flavor. Natural cheese can give a grainy mouthfeel to cheese sauce, and an emulsifying salt such as disodium phosphate may be needed to smooth out the texture.
Dried and enzyme-modified cheeses deliver the key elements of cheese flavor in a concentrated form. They can be used in a variety of foods, such as soups and sauces, although many of these ingredients should be used within a few months. Enzymes continue to work on the different cheese components after the product has been made, so the flavor profile will change over time. Compounded flavors are usually more stable and have many of the same chemical compounds in liquid form, but contain very low amounts of residual enzymes.
When a dairy-containing food is cooked or baked, reaction flavor compounds, called lactones, form from the dairy fatty acids. Compounded flavors can improve the flavor of products that do not reach a high enough processing temperature to induce desirable dairy reaction flavors. For example, a cooked-cream flavor could impart a caramelized dairy note in a cold-blended cream sauce or filling. Compounded flavors may also be used when a dairy ingredient, such as powdered cheese, could cause undesired browning reactions because of its large percentage of whey and lactose.
Compounded flavors have other benefits. Liquids or pastes may not have the lumping problems associated with dried dairy ingredients. Compounded flavors can also be used when the product developer wants uniformity, or has nutrition or health concerns. Highly concentrated flavors are generally economical and require little storage space. For example, "One can take 10% of the natural cheese out of a formulation and replace it with 1% flavor," says Farshid Eftekhari, manager of dairy flavor research, Chr. Hansen Inc., Milwaukee. "Then you replace the other 9% with a filler that is cheaper than the original cheese. This change will result in a finished product that is much more economical."
Compounded dairy flavors can add roundness or subtle background notes. For example, a cooked-cream flavor will add fullness to a cheese sauce. Even though the compounded flavor may not be delivering the prominent characteristic flavor of the food, it can provide a base that delivers the prominent flavor better or masks undesirable flavors from other components in the system.
Composite flavors are a simple way to achieve a complex flavor when the process alone will not accomplish the desired result. For example, a buttercream-cookie flavor might contain elements of butter, cream, brown sugar and vanilla in a single container. A yellow-cake flavor might be a composition of butter, vanilla and egg notes.
Chuck Bullens, group leader of dairy applications, Bush Boake Allen Inc., Montvale, NJ, says his company has seen increased demand for complex dairy flavors that mimic restaurant menu items. "We are often asked for decadent flavors like crème brûlée or cheesecake that will end up in products such as pudding or ice cream. We research what goes into these desserts and design a balanced flavor that will resemble the actual dessert," he explains.
Mixing flavorful molecules of natural or artificial origin creates compounded non-dairy flavors. Coconut fat might mimic the mouthfeel of butter fat, and hydrolyzed yeast or hydrolyzed vegetable proteins can enhance flavor and add savoriness to flavors. Natural flavors result from microbial fermentation or the extraction or concentration of natural ingredients. Artificial flavors are derived through chemical means. In Europe, a third classification of flavors is nature-identical; these flavors are derived chemically, but identical to compounds found in nature.
According to Eftekhari, microbial fermentation or enzymolysis is often used on dairy base materials to arrive at flavor compounds of interest. The resulting compounds may provide intensified profiles of cream, butter, cheese and milk. When creating such intense dairy flavors, the flavorist tries to reduce the compounds that cause off-flavors. Certain peptides can taste bitter, long-chain FFAs can taste soapy and fermentation can generate undesirable sulfides. Consumers are often able to detect these off-flavors, so minimizing these flavors is a major goal.
Eftekhari describes creating an intense dairy flavor: "Imagine a block of table cheese, and through microbial fermentation and enzymolysis, you enhance the flavors that are most desirable in that Cheddar cheese. You end up with a paste or semi-paste that has an intense flavor profile and is loaded with desirable compounds — five to 30 times what you started with. Then, through heating, you can generate lactones and other heat-related compounds. Protein breakdown, fat hydrolysis and carbohydrate reactions result in strong dairy flavors. The reaction products that are responsible for these intense flavors include amino acids, peptides, FFAs and Maillard browning products."
Manufacturers often create stand-alone flavors or highly concentrated building blocks that have some characteristic of the desired product. By combining various building blocks into "cocktails," a flavorist can quickly address a customer’s needs and put together combinations that are reminiscent of almost any flavor. For example, to create a goat-cheese flavor, the flavorist may first examine the ratio of fatty acids present in a typical goat cheese and then pick from various on-hand building blocks.
Eftekhari says that industry customers often ask for very specific flavor profiles: Cheddar cheese with pronounced buttery or aged notes, Italian cheeses such as Asiago and Reggiano or pleasantly sulfury cheeses, such as New York or Vermont Cheddars.
Importance of minor constituents
Many dairy flavors contain low-level compounds that are essential to the characteristic flavor profile. Canadian black diamond cheese has a composition that clearly illustrates this principle. This aged Cheddar cheese is noted for its pleasantly sharp, savory, umami-type flavor, a result of its sulfur content and broken-down milk proteins. According to Eftekhari, 99% of the population wouldn’t be able to consciously detect the sulfur because it contributes to the cheese’s flavor below a threshold level. But if the sulfur component of the flavor is taken away, consumers will miss it and know that the flavor has changed, although they won’t know why.
Chandan agrees that minor flavor constituents cannot be discounted. "Whenever you synthesize a flavor, you are often targeting a specific, predominant chemical. Sometimes you run into trouble, however, because flavor is not really one chemical but a mixture of chemicals. Take, for example, an EMC. Sometimes you have a predominant flavor compound, but you don’t have the whole picture. When you put it in a system, it may not seem well-rounded, but really harsh," he explains. In some cases, this harshness can be masked with other ingredients or flavors, but it is important to select a flavoring that is not overly harsh, yet still cost effective.
The carrier or solvent used to deliver a flavor can influence how the targeted flavor comes off in a product. When spray-dried, a flavor will be altered both by the carrier and heat from the drying process. Dextrose, modified starch and maltodextrins frequently act as carriers for spray-dried flavors. For this reason, a spray-dried flavor may taste different from a liquid flavor in ethanol, even if the primary flavor chemicals were the same. For spray drying, low-viscosity carriers readily give up water and therefore make spray drying more efficient.
Ideally, a good flavor carrier should not interfere with the flavor characteristics of a food product. Ethanol is usually the flavor carrier of choice in liquid flavors because it is an inexpensive, water-soluble solvent that helps prevent microbial deterioration. Propylene glycol also does not propagate bacteria. If the carrier can be tasted in the finished product, one of four problems could be occurring: the concentration of the flavor is too high; the solvent in the flavor is inappropriate for the application; the flavor is not being diluted by the water content of the food; or the process does not involve enough heat to drive off the carrier. If the flavor of the carrier is objectionable and there is no way to realistically make the flavor work in the finished product, the flavor supplier will need a different carrier.
Skim-milk powder, whey powder and other dairy-derived ingredients are commonly used in baked goods. According to Bullens, bakeries often change suppliers or processes to reduce costs, but because the usage levels of dairy ingredients are usually quite high, such changes often affect the finished product flavor. A compounded dairy flavor may help compensate for flavor change so that the product will taste more like its original formulation. Because many other ingredients in baked systems are in dry form, a dry flavor is often convenient.
Processing can have a profound affect on the finished flavor of a baked product. "Baked goods go through various manipulations such as a mixing, proofing and holding at various times and temperatures. You want a flavor system that will hold up to all of these processes, so you need to work with products that are heat-stable and won’t lose all the volatile components during baking. Whether you’re making bread with a butter flavor or a cultured dairy characteristic, you want to make sure that it’s still going to be there after the entire process," says Marty Anker, assistant application and development manager, Kerry Ingredients, Beloit, WI.
Chocolate and confectionery products often derive some flavor from dairy ingredients, such as dry or condensed milk, milk crumb, malted milk and buttermilk solids. To accentuate chocolate flavor, some formulations contain lipolyzed butterfat — the butterfat was processed under highly controlled conditions and some short-chain fatty acids exist in free form.
Cheese powders and other dairy-based ingredients are used in snack-food seasonings for tortilla chips, potato chips, crackers and puffed snacks. To keep costs down, the cheese powders used often contain whey, milk solids, hydrogenated vegetable oil or maltodextrin as replacements for some of the cheese solids. For mellow cheese flavors, Monterey Jack, mozzarella or mild Cheddar can be used, while blue, Parmesan, Romano or sharp Cheddar cheese can add a sharper flavor. Dairy flavors may be incorporated in the base formula or topically applied as a dust or slurry.
In ice-cream manufacture, avoiding off-flavors is a major concern. The best ice cream uses fresh cream that provides its own desirable, delicate flavor, so it is important not to introduce other flavors which may contribute unclean notes. When fresh cream cannot be used for cost or other reasons, it may be necessary to add dairy ingredients or flavors that help improve the flavor. But, says Bullens, "You want to avoid any dairy flavors that taste like movie-theater popcorn or give any sour notes reminiscent of partially digested milk. These types of flavors make the consumer think the ice cream is not fresh."
If milk used in ice cream has an oxidized, stale or "cardboard" note, some compounded flavors can actually accentuate the off-flavor. Also, some components in the ice-cream base can contribute flavors that may need covering up. Using milk powders that underwent high-heat treatment, or making substitutions between nonfat-milk sources, can affect the flavor profile because of the high levels used to build the solids content. Low-heat milk powder delivers a cleaner, better flavor than high-heat powders because less denaturation of milk proteins and carbohydrates has occurred. However, manufacturers often move away from the most desirable forms of milk powders to reduce costs. A flavor may be added to bring the product closer to its original profile.
Flavors can also enhance dairy notes or increase the perception of decadence and creaminess that comes along with fresh butterfat. According to Bullens, a current trend is blending ice cream with various types of rich bakery products, such as cookie pieces or dough. The flavor of the ice cream must be compatible with any inclusions and must deliver the flavor profile consumers expect.
Coffee creamers and whiteners that incorporate dairy, nut and liqueur flavors have presented new opportunities for the flavor industry during the last five years. Enough flavor must be built into the creamer to deliver the desired flavor strength when diluted by coffee. Because many newfangled creamers are nonfat or lowfat, enzyme-modified flavors or dried compounded flavors can contribute a butterfat-like mouthfeel.
Ready-to-eat pudding is another product that gets some of its flavor from dairy ingredients or flavors. Many times, manufacturers will substitute vegetable oils for milkfat. These can contribute a flavor of their own or may prevent carry-through of other flavors, and because consumers expect a rich, butterfat flavor character that vegetable oil won’t contribute, a compounded flavor may be in order.
Yogurt derives much of its characteristic flavor from the bacterial culture used. Dry milk is often added to fluid milk and cream to produce a high-solids yogurt with a smooth, creamy mouthfeel. Fruit and vanilla flavors can complement the yogurt’s basic flavor.
Cheese- and sour-cream-based sauces can seem more rich and indulgent with dairy flavors that do not contribute significantly to their caloric content. Cost is often a major concern in the manufacture of dairy-based sauces, and whey protein is an inexpensive ingredient that can make up for lack of other dairy solids. Whey protein often carries an undesirable fruity or sweet note because of its lactose content. A compounded dairy flavor can help add richness and mask undesirable notes from ingredients like whey; minimizing undesirable notes is critical so that the cheese flavor comes through properly.
Flavors for special needs
Certain populations demand dairy-free products, but may still crave products that possess dairy’s flavor characteristics, such as those who are lactose intolerant, observing religious dietary laws or following certain types of vegetarian or other dietary regimens. Dairy-like flavors made without natural dairy components can be created for products such as vegan soy "cheese." Consumers generally want vegan cheese analogues to taste like real cheese, so a synthesized cheese flavor might simulate the genuine article. Or maybe a creamy flavor is needed in a dairy-free coffee beverage, in which case an artificial cream-type flavor could provide diacetyl notes to round out the profile.
Concentrated or compounded dairy flavors are very useful in low-fat products. For instance, a compounded cream flavor may provide a rich, full flavor without real cream. In low- or reduced-fat products, flavor and desirable mouthfeel are often reduced as well. Replacing fat with a smaller amount of fermented cream or butter oil may regain some of the original mouthfeel and flavor.
Many flavor houses have been custom designing flavors meant to work specifically with soy ingredients. A product must contain 6.25 grams of soy protein per serving to make the new FDA health claim, so some grassy, brown or beany flavors may come through in the finished product. Because many people are interested in the health benefits of soy, but have varying levels of tolerance for its flavor, the food technologist may want to mask the soy flavors as much as possible.
The flavor characteristics of the soy ingredient and amount of soy loading need to be considered when developing a flavor system. "Flavors need to be layered correctly in a soy-containing product," says Bullens. "We generally put in a flavor that will overlay the flavor contribution of the soy and then build upon that with the primary flavor of the food product." Like soy, whey ingredients often act as replacement proteins. Then, he says, "the challenge becomes to cover up the fruity or sweet notes contributed by the whey."
Screening for development
Dairy flavors can be screened in several ways. For a quick, easy screening, dairy flavors can be tasted simply in warm water, salt water or milk. Incorporating the flavors into a simple system, such as cheese sauce or cream cheese, is also a good approach. To get the most information, the flavor should be incorporated into an application that is similar to the product that will ultimately be produced. As when screening any flavor, dairy flavors should be tasted in an environment free of competing odors.
When deciding which form of dairy ingredients or flavors to use, the desired degree of browning during processing and preparation needs to be taken into account. In baked goods, browning lends an attractive appearance and flavor to the product, but in other products, such as cheese- or sour-cream-based sauces, browning may not be desirable. When a protein source (such as whey) and a reducing sugar (such as lactose) are heated together, the Maillard-browning reaction takes place. A powder or paste low in whey and lactose may be needed to prevent discoloration. Alternatively, compounded flavors may be used because their typical low usage levels do not add much of the troublesome components. Also, flavors made from cultured dairy systems have had most of the lactose used by microorganisms during the fermentation process, so little remains to undergo heat-induced reactions that result in browning and off-color developement. Another option is to separate the protein and sugar components in a formula and add one at the end of the process to prevent contact with each other during heating. Finally, processing products at low temperatures and short times can also reduce browning, although the product developer needs to consider how much heat the consumer will apply to the finished product.
Solubility is also a critical factor in flavor selection. "You have to be aware of whether the flavor you are using is water-soluble or oil-soluble to determine if it’s going to combine with one of the phases properly," says Bullens. "If it’s a water-soluble product, you need to make sure that the flavor gets hydrated properly, especially when there are many other components competing for water. In products like baked goods, in which you usually have a large amount of fat, you can sometimes go with either a water- or a fat-soluble flavor, depending on how the product is put together and what is easier to handle in the plant."
When choosing the best option for a product, Chandan stresses the importance of working with a supplier that specializes in dairy flavors. "If I want to accentuate a creamy or milky flavor in a product that has no fat in it, then I need to work with a supplier that can help me choose flavors that work with other ingredients in my system. Whether the finished product is fat-free, protein-free or high protein, you have to marry the flavor system to the food system."
Choosing flavors for a food product is often an arduous task, and ultimately, says Eftekhari, arriving at the perfect flavor will require some blood, sweat and tears in the lab. "You need to screen a lot of flavors and ask yourself, will this flavor make my product taste buttery and creamy, or harsh and lipolyzed?" Only testing will tell.
Christine M. Homsey is a food scientist with the consulting firm of Food Perspectives in Plymouth, MN. She has developed products for the grocery and restaurant industries, and recently completed a graduate degree at the University of Minnesota. Homsey can be reached at [email protected].
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