Coffee and Tea Beverages

 Coffee and Tea Beverages
July 1996 -- Design Elements

By: Lynn A. Kuntz
Associate Editor*

*(Editor since July 1996)

  Coffee and tea share certain similarities. Both require the aqueous extraction of flavor, color and physiologically active compounds from plant materials to create a beverage. From each, it also is possible to make a wide variety of formulated beverages in a range of different formats. Unfortunately, coffee and tea also shared the scorn of 19th century author William Makepeace Thackeray:  Why do they always put mud into coffee on-board steamers?  Why does the tea generally taste of boiled boots?  Optimizing the flavor of coffee- and tea-based beverages requires understanding how processing and flavor addition affect finished products. With a little effort, product designers can create products that keep today's consumers from echoing Thackeray's words.Back-grounds  Two species of coffee plants are used for the commercial production of coffee: Coffea canefora, or robusta; and Coffea arabica, or arabica. One other type, Coffea stenophylla, produces beans suitable for coffee, but its cultivation is not cost effective. Coffee grows in more than 50 countries with warm, humid climates, at altitudes ranging from sea level to 6,000 ft. and above.  Robusta coffees grow at lower altitudes. They have more disease resistance, less demanding growth requirements, and higher yields than arabica coffees. The slower-maturing arabica thrives at higher altitudes and is considered a higher quality coffee. Robustas produce a harsher flavor and end up in more economical products such as instant coffee and blends for mass-market ground coffee. In addition, robusta contains about twice the caffeine as arabica.  A number of different botanical varieties fall within these two commercial species. While they have some flavor differences, the main reasons for growing a particular variety are agricultural: growth and yield considerations. Geography and climatic conditions have a greater impact on the end result than the botanical variety.  "The origin of the coffee is extremely important," says Kitty Juttner, senior marketing manager, Flavor Division, Cultor Food Science, East Winsor, NJ. "Each growing region and location within that growing region produces coffee with distinctly different characteristics, such as the acidity, 'wineness' and body. These characteristics impart a different flavor profile to the finished product. In general the more sophisticated customers want a better quality blend. The milder coffees lend themselves better to flavoring. However, it is important to select a blend of coffees that complement the flavor profile that you are trying to achieve."  Origin is important in one sense. "It's what determines the characteristics and flavor of the coffee," says Leonard Zuckerman, president, Zuckerman, Kramer and Associates, New York. "The flavor is a function of the altitude and the type of soil and other related factors. Columbian and Ecuadoran coffees are basically the same type of coffee, but the Ecuadoran crop isn't maintained or processed as well, so it produces a lower quality coffee."  Economics also plays a large role in the type of coffee used for a given application. Mass-market products typically blend different coffees based on price.  "Most mass-market coffees try to maintain a certain flavor profile, but at the same time they have to stay competitive," says Zuckerman. "Specialty vendors can sell better types of coffee because their customers will pay those kinds of prices. Plus, it's easier to buy 5,000 bags of good coffee than 50,000 bags of good coffee."  Two seeds form in each of the ripe berries produced by the shrub-like coffee trees. Two methods are used to process the bean. In the dry method, the fruit dries on the plant or is dehydrated by the sun after harvesting. Milling separates the beans from the debris. In the wet method, the cherries are steeped and fermented for up to 24 hours. A water spray removes the pulp, and the beans are dried in the sun or in tumble dryers. A hulling machine removes the protective membrane that surrounds the bean. This process creates a slightly more acidic coffee. The beans are cleaned, sorted and graded.  To create coffee's characteristic flavor, odor and appearance, the green beans must be roasted. Roasting typically takes from 1 to 17 minutes at temperatures between 380° to 480°F. The longer the roast, the deeper the flavor and color of the beans. The degree of roast is designated by names such as American, French or espresso, but these are only relative terms, not standards. Roast time and temperature also depend on moisture and density. The degree of roast can be standardized by visual comparisons or by a colorimeter.  During roasting, moisture is driven off and a number of reactions take place to form the flavor. Experts estimate that coffee has over 800 different compounds that contribute to the flavor, including sugars and other carbohydrates, mineral salts, organic acids, aromatic oils and the methylxanthines, including caffeine. The level of caffeine actually decreases as the degree of roast increases. The typical pH of coffee is around 5, but it often depends on the degree of roast.  "The degree of roast affects both the intensity and character of the flavor of the coffee, and sometimes it can intensify or subdue both desirable and undesirable characteristics," notes Ed van der Loo, technical director of Cultor's Flavor Division. "It also affects the perceived body of the finished brew."  After roasting, the beans must be quickly cooled to preserve the desired flavor. Most large commercial operations use water quenching. Excessive water can accelerate staling and adversely affect the flavor. Air jets are used for gourmet beans, but the process can be more difficult to control.  Sensory evaluation of coffee is referred to as "cupping." The method involves placing 7.25 grams of ground coffee in a cup and adding 100 ml of boiling water. Both aroma and flavor are evaluated. The industry uses about 50 specialized descriptors -- such as earthy, nutty, spicy and turpeny -- to describe the flavors found in coffee. Acidity and body, which is partly a function of suspended solids, also contribute to the overall flavor profile.  "Coffee has a certain amount of bitterness or astringency," says Diane Barrera, technical director, Borthwicks Flavors, U.S.A., Haupaugge, NY. "You expect a dark, bitter character, otherwise you have mocha. Browning reactions occur during the roasting process. It also forms mercaptans, and while they have an unpleasant odor, some of that dissipates during the roasting process."A leaf from the book  All tea comes from one type of tree: Camellia senensis. The young shoots containing the first two leaves and the unopened bud are preferentially harvested, generally by hand, since it is difficult to mechanically harvest only the tips.  The green leaves undergo further processing to create one of the three main types of tea: black, oolong or green. Green tea is steamed or pan-fired to inactivate the enzymes, then rolled and dried to approximately 2% moisture. The leaf maintains a green color, certain polyphenols, and a significant level of vitamin C. Green tea contains between one-third and one-half the caffeine of black tea. Oolong falls between green and black tea. It is slightly withered and fermented. One additional variety rarely found outside China is Pouchong, which undergoes even less processing than oolong.  The traditional process for black tea takes several steps. First the leaves are withered -- that is, the moisture is removed by ambient or heated air. They are then mechanically rolled to break the cells and release their contents, and they are sifted. Then the leaves are fermented in a cool room which generates the characteristic flavors. After fermentation, the leaves are fired, or dried, to halt fermentation and to bring the moisture to the appropriate storage levels. The modern, mechanized method is called crush, tear and curl (CTC). A machine compresses withered tea leaves into curled balls and then these are dehydrated.  After drying, the leaves are graded by size. Black tea includes whole and broken leaf grades. The whole leaf grades are (from high to low) Orange Pekoe, Pekoe and Souchong. The highest quality Orange Pekoe, or Flowery Orange Pekoe, contains the highest proportion of leaf buds. Souchong contains many large leaves generally not from the branch tips. The broken leaf grades include broken Orange Pekoe, broken Pekoe, broken Souchong, fannings and dust. Broken leaf grades infuse more quickly, resulting in a darker color and stronger flavor, but they have a shorter shelf life than the whole leaf. Oolong grades range from Extra Fancy to Common. Green teas do not follow a standard grading system but may carry certain quality appellations, such as Gunpowder (young, tightly rolled leaves) and Twankay (unrolled, poor quality leaves).  Teas are generally blended, although estate teas can be found. Blended teas may carry the name of the area in which they were grown, such as Ceylon, China or Darjeeling. Other blends create a characteristic flavor, such as the strong-flavored Irish Breakfast tea. Some may be flavored -- for example, Earl Grey contains oil of bergamot. In general teas from India have a darker color, stronger flavor, and a higher caffeine level than those from China.  "The geographic origin of teas is critical in terms of flavor," says Barrera. "A Ceylon tastes quite different from an Assam or Darjeeling. Most Americans prefer black, Ceylon tea. They also like the character of an oolong, although most would not recognize it as such. In most bottled teas, the companion flavor characterizes the flavor rather than the tea, so its type or origin is not as important as long as it complements the finished product."  Tea, particularly green tea, has been associated with numerous health benefits: cancer prevention, reduction of total cholesterol levels, and even the reduction of dental caries. However, the grassy flavor of green tea is not always well received.  "You will probably see a proliferation of green tea products on the market. There will have to be some mainstream styling. You're going to see lemon iced green teas because people expect that. But you're likely to see more creative products with tropical fruit flavors, or blends with herbs that are good for you, like chamomile," predicts Barrera.Modern times  People have traditionally used whole-bean coffees and loose tea leaves to brew their beverages. Today, these formats are still preferred, particularly for high-end products. However, the quest for innovation, economy and ease of use has changed the ingredients and the types of products.  While the demand for whole-bean coffee increases daily, most cups in this country come from ground coffee. This form delivers an initial caffeine jolt sooner, but it certainly doesn't contribute to the subtle nuances of flavor. Exposure to air and moisture rapidly deteriorates the flavor of roasted coffee. Grinding the beans increases the exposed surface air and accelerates oxidation of the aromatic compounds. Coffee aficionados swear that roasted whole beans only have a one- to three-week shelf life, so their opinion of pre-ground coffee doesn't bear repeating.  To preserve the flavor of whole-bean and ground coffees, specialty roasters use nitrogen-flushed vacuum packages with a one-way valve that allows the carbon dioxide produced by freshly roasted beans to escape. Canned coffee must be allowed to de-gas (and, subsequently, de-flavor) before canning or the cans would explode.  Near the turn of the century tea bags were developed, first of silk and gauze, then of filter paper. Although purists may argue the point, this does not change the flavor, but it may cut down on the opportunities to read your fortune.  Beyond these basic beverages, more options emerge. Although many of us drink coffee and tea to enjoy the effects of caffeine, others like these beverages without them. Decaffeination removes about 96% to 98% of the naturally occurring caffeine in a coffee bean.  Caffeine solubilizes in water at temperatures above 175°F. However, using water as the solvent removes much of the flavor and aroma. In the direct method, rinsing with a solvent at elevated temperature draws off the caffeine. Methylene chloride makes a good solvent because it removes the caffeine with minimal effect on the flavor compounds. Some safety concerns have been raised with methylene chloride, but it is highly volatile (it boils at 103° F) and it is unlikely to stay around after encountering roasting and brewing temperatures. Its use may be limited due to environmental concerns, however.  In the indirect method, the coffee or tea is rinsed by water. This water is treated with a solvent, usually methylene chloride, to remove the caffeine. The same water is reused, so the level of flavor components builds up with net flavor loss over subsequent batches. This method is also called the water process or European water process.  The Swiss water process uses only carbon-filtered water to extract the caffeine from green beans. Soaking and draining steps are repeated until the caffeine is removed. This process is fairly expensive and it strips out much of the flavor.  Ethyl acetate and carbon dioxide also act as solvents for caffeine. These often carry the label "natural process." These solvents are generally considered safer than methylene chloride. Also, they remove less of the flavor.  "Because you are decaffeinating a green bean, with the exception of the Swiss water process, you won't get a significant flavor difference among the different methods," Zuckerman says.  In addition to removing the "kick," the decaffeination process can change the flavor. Caffeine, an alkaloid, tastes bitter. The degree to which it influences the finished product is debatable, but considered detectable.  "Removing caffeine affects the perception of flavor," says van der Loo. "It seems less strong and has less body. The method used for extraction doesn't affect the flavor, however. Usually the use level of an added flavor is adjusted for decaffeinated coffee."  "It's one of those subtle elements that we consider for flavor matching," says Carlo Colesanti, president of Cultor's Flavor Division. "Knowing how to modify the flavor system around the caffeine level helps the finished product flavor."  For the consumer in a hurry, the market supplies instant coffee and teas. These products are the coffee or tea solids that product designers often use for formulation. After brewing or infusing a fairly strong solution, the liquid is dried to a powder via spray-drying or freeze-drying. Regular spray-drying exposes the liquid to high temperatures and oxygen. Since neither of these conditions are favorable to the flavor volatiles, the result is not easily confused with fresh-brewed. Aromatic oils can be added back to improve the flavor.  Other forms found in the product development lab are coffee or tea extracts, concentrates or essences. These add flavor to prepared beverages without the difficulties of brewing on site. They also produce a more standardized product.  Because brewing coffee or tea as a beverage is an extraction process, most consider extracts to be a form of the natural or naturally brewed beverage. As always, for commercial processes, the appropriate label on a finished product depends on the end-user's interpretation.  "There's no standard of identity for these products," says Bruce Roberts, manager of beverage business development, McCormick & Wild, Hunt Valley, MD. "In theory if the process is something that could be done at home in your kitchen, it can be called tea or coffee. There's some debate in the industry on the appropriate labeling."  The source of the tea or coffee greatly influences the characteristics of the extract, and so may the extraction method.  "Often extraction has a tendency to exacerbate negative attributes," says Roberts. "Things like bitterness, astringency and off-notes may increase, especially with traditional extraction methods. CO2 extraction may result in a better flavor, but it's still best to start out with a good flavor source."  In addition to real tea (leaves from C. senensis), herbal teas have risen in popularity. These should actually be called infusions or tisanes because they typically do not contain tea leaves, although some blends appear on the market. A wide range of ingredients have gained various reputations for promoting health or well-being. However, many of these ingredients create characteristic flavors, which many American palates consider unpleasant. The bitterness that ginseng may contribute is one example.  "One of the strategies is to put these herbals in at a low level so the taste doesn't come through," says Roberts. "Then you can add much higher levels of pleasant flavors. Or you can use flavors that are designed to supplement or complement the flavors from some of these ingredients. It might still taste bitter, but it won't have a medicinal character. You can change the profile or the acidity to help the overall flavor."Filtering through the options  A number of different beverages may be created using coffee and tea as the base. The technology varies based on the end product.Whole and ground coffee. By selecting different types of coffee beans and varying the roast, one can obtain a wide range of products. The brew process also greatly influences the result -- regular versus espresso, for example.  "There are regional preferences for the type of roast," observes Zuckerman. "Generally as you move from the East Coast to the west, the roasts get lighter. Europe prefers the darker roasts. Oriental countries have traditionally preferred the taste of instant coffee, but Japan is starting to develop a taste for some of the darker roasts."  Most flavored coffees carry brown or dairy-type flavors. Vanilla, nuts, chocolate or cinnamon are popular. Chicory is used for New Orleans style coffee. Adding flavors can help extend the shelf life of a coffee by disguising changes due to oxidation and staling, or from processing or decaffeination.  "Flavored coffees are not necessarily a replacement for that morning cup of coffee," says Barrera. "They are often thought of as a luxury item. In most cases they use a good quality bean; the object of adding flavors is not to cover up a bad product. However, if the object is to create an inexpensive, mass-market product, adding flavors can help hide some of the defects."  Flavors can be added to whole beans or ground coffee. Typically the flavor levels lie between 2% to 3% by weight. Usually liquid flavors are used, but dry forms can be added to ground coffee. The process differs somewhat depending on the type of product.  For whole-bean coffee, the flavors are typically suspended in a liquid system -- usually propylene glycol or a vegetable oil system. Then they are atomized or gradually applied to the beans in a rotating mixer to avoid hot spots. It takes 15 to 30 minutes to coat the beans and another 15 to 30 minutes for the beans to absorb the flavor.  "We need to develop flavors with aroma, not volatility," says Jeff Nichols, vice president, sales and marketing, Beck Flavors, St. Louis. "They must be easy to apply and leave a glossy sheen on the bean. Appearance is very important."  For ground coffee, initially the beans were flavored prior to grinding. However, this led to serious problems. Running different flavors through a grinder cross-contaminated the flavors. Now, many manufacturers use the same types of flavors used on whole beans, but in dry form, and they dry-blend them into ground coffee.  "With this method there's enough moisture in the coffee to provide color transfer between the flavor and the coffee. So after about 24 hours, the color completely equilibrates," Nichols says.  The flavor system has to be developed to withstand a brewing temperature of over 190°F for at least 15 minutes. Otherwise it may produce a wonderful aroma during brewing, but the finished product will be sadly lacking in flavor.  "When coffee is brewed most of the volatiles are going into solution," says John Simons, director of marketing, Robertet Flavors South Plainfield, NJ. "Some are flashing off and some remain for flavor impact. Some volatiles will be lost, so you have to balance the flavor system understanding the temperatures and the exposure to oxygen."  Flavored coffee needs a low-acid, full-flavored bean. Usually a light or medium roast is used on coffees that are to be flavored, but there are exceptions, like a darker roast for an espresso-type beverage.  "The top four beans that are used for flavored coffees are Colombian, Mexican, Costa Rican and Guatemalan," says Nichols. "Eighty percent use a single source rather than a blend. You want a bean that complements the flavor, but doesn't overtake it. You're looking for a balance where neither the coffee nor the flavor predominates."Bag and loose tea. Teas also may contain additional flavors. These range from the more traditional oil of bergamot or orange peel to today's popular fruit flavors.  "In general, brown flavors or vanilla don't go well with tea, especially the green teas," says Barrera. "Fruit works well because the flavor of tea tends to be fruity."  The flavors used may come from many sources: dried material, such as licorice root or ginger; actual spices, such as clove; water- or oil-based flavors; or essential oils. As with flavored coffee, the most important element is that the mixture, and the subsequent flavor level, remain consistent.  "For tea bags, the preferred type would be an encapsulated flavor because of its larger particle size," says Roberts. "A regular spray-dried product could sift through the bag during handling."Instants. Regular instant coffee and tea consists solely of coffee or tea solids, but those with flavor show a few other ingredients on the label. These are mainly dry ingredients, but they vary depending on the type of beverage designed.  Most contain a sweetener. If sugar sweetens the product, it also serves as a carrier or bulking agent. But products that use a high-intensity sweetener often require maltodextrin or other bulking agents to act as a carrier and provide body.  "The flavor requirements for an instant product are much less stringent in terms of temperature than those used for a brewed product," notes Nichols. "If you used the same type of flavor that you used in the brewed product, it would be much too harsh. Typically the flavors are spray-dried and dry-blended with the coffee or tea solids."  With flavored, sweetened instant tea, often the tea serves as the background flavor and provides the color. The product is designed much like a powdered drink beverage; flavors and acidulants often provide the characterizing flavors.  Instant flavored coffee goes one step further. In addition to coffee solids, sweeteners and flavors, many of these exhibit a cream-like character. Dairy products may be used, but it's more likely that a nondairy system would be used, including fats, proteins, emulsifiers, clouding agents, thickeners.Ready-to-drink. Plain, unsweetened tea may take up a shelf facing or two in the beverage aisle, but most RTD products contain sweeteners and flavors.  "Tea has a very delicate flavor, so it's not difficult to overpower it with some of the fruit flavors," says Simons. "The traditional hot tea drinker is probably not the main consumer of these products. You are trying to get non-consumers to like the flavors."  The technology behind formulating RTD tea products is similar to regular still beverages. Water, sweetener, tea and acid are combined. The result is usually a high-solids, high-acid product similar to a juice.  "Typically, coffee and tea are served hot, which increases the volatilization of the aroma," says Jeff Carlson, western sales manager, T. Hasegawa U.S.A. Inc., Cerritos, CA. "Ready-to-drink coffee or tea beverages are generally served cold, requiring flavors to enhance the aromatic top notes and replicate the delicate aroma of fresh-brewed."  Because the big sales surge in RTD teas seems to be slowing, the new growth areas may be novel combinations. Mixing teas and herbs may be one method.  "There is still room for expansion in the tea business," says Don Wilkes, president, Blue Pacific Flavor & Fragrances Inc., Irwindale, CA. "There will be more attention to the technology and the processing side. That will allow the development of better and fresher flavors. There will probably be a change to a more fresh-brewed taste. American-style RTD tea is not popular in England, for example, because the tea flavor is too light."  While many predict that RTD coffee could hit it big, the wave has yet to strike the shores of the United States. These products do enjoy a high degree of popularity in Japan, where they are sold as both hot and cold beverages, usually from vending machines. However, these beverages probably will require reformulation to appeal to the American palate and to fit in with the American style of manufacturing.  Canned RTD coffee beverages first appeared in Japan in the early 1960s. They took the form of sweetened milk drinks with added coffee flavors.  "The milkiness and sweetness have decreased and coffee has become the dominant flavor," says Carlson. "Recently, manufacturers have differentiated their products by the roasting, the origin of the coffee beans and their proprietary brewing process."  "Many Japanese products are sweetened with a lactose/fructose mixture and they taste very sour to Americans," says Colesanti. "Their flavored coffee tends to be either an American blend or a French blend, sweetened. That's what they considered flavored. Now they are starting to add flavors like Irish creme or mocha."  Formulating RTD coffee beverages presents a number of challenges. Consumers are likely to use coffee shop or restaurant versions as a benchmark -- products such as cappuccino or Thai iced coffee.  "In coffee shops, iced coffee is the dominant craze, especially iced cappuccino and iced mocha," says Nichols. "The problem with formulating a commercial version is that it has to taste like fresh coffee. You need to look at thermal systems, aseptic possibly, that help to protect the integrity of the beverage."  One of the biggest hurdles is that these products require thermal, generally retort, processing, so ingredients must be thermally stable.  Because of the complexity of these products, other issues arise. Start combining highly volatile products, proteins and carbohydrates, add heat and then watch the fun begin. Many of the ingredients -- proteins, carbohydrates and stabilizers -- can change the impact of the flavor. For the right flavor, the pH should be slightly acidic. This may affect the protein ingredients as the pH of the mixture approaches their isoelectric point. Emulsification systems must withstand the heat during processing and prevent separation throughout storage. And although cans are popular elsewhere, American consumers have developed a preference for beverages in bottles. So there are potential light-exposure problems to deal with, too.  "If you increase or decrease the concentration of coffee, it has a lot of different characters," notes Nichols. "You can add certain spices to it and it tastes just like cola. When you are talking about ready-to-drink, you don't always have to think of dairy."  Other product designers haven't stopped at hot and iced tea and coffee. They have developed frozen novelties with tea and frozen tea concentrate. There's coffee beer and coffee soda. Whatever form the coffee or tea product takes, the proper application of 20th century technology will help avoid 19th century flavor disappointments. If he were still around, William Thackeray, no doubt, would be pleased.Back to top<