Flavoring Confections

 

Flavoring Confections
October 1995 -- Applications

By: Lynn A. Kuntz
Associate Editor*
*(Editor since August 1996)

    At some point in our lives most of us have popped a sugar cube into our mouth for a quick sugar fix. However, unless your name is Trigger, plain sugar lacks pizzazz. In candy, flavor transforms sugar into something much more tempting.  Flavoring confectionery items can challenge those who design these products, technically as well as creatively. Knowing the problems, pitfalls and possibilities can sweeten the process.  Many different categories exist in the candy industry. This article will focus on non-chocolate applications because chocolate has unique characteristics and requirements. This is not to say that the rest of the confectionery products make up a homogeneous lot. To the contrary -- often different categories require specialized flavor systems. Form, ingredients, process, and even marketing considerations drive the flavor requirements.A flash in the pan  Most traditional candy-making involves taking a sugar solution to an elevated temperature. As the temperature rises, more sugar can dissolve, increasing the solids content in the hot solution. As the solution boils, water evaporates, which further lowers the moisture. As the solids increase, the boiling point increases.  A hard candy with a moisture of 1% to 2% requires a lengthy exposure to process temperatures that exceed 300 degrees Fahrenheit under atmospheric conditions. This leads to the first problem: flavor volatile flash-off.  Extended exposure to high heat results in significant flavor loss. The longer the time, the more pronounced the problem becomes. So, candy-making has evolved to where the manufacturer adds the flavor after cooking. However, the cooler the mass, the more viscous it becomes. The cooked candy mass must remain pliable enough to allow the flavor to be manually or mechanically dispersed throughout.  "Much of the problem in the traditional method occurs when the candy comes out hot, even though it may have been vacuum-cooked," observes Michael Lynch, business unit director, Haarmann & Reimer Corp., Springfield, NJ. "The flavor is poured on top of the candy in a sort of pool and kneaded into the hot mass. Just that exposure on the hot surface causes a great deal of flash-off, or evaporation of the volatile components."  Candy manufacturers can minimize flavor flash-off in several ways. First, minimizing the surface area in an open kettle process exposes less surface to the atmosphere. Most newer equipment addresses the problem with closed systems and vacuum-cooking. In a closed system, volatiles remain in the vessel and return to the product. With some equipment the flavors can be injected directly into a closed mixer in a continuous process, minimizing flash-off. The candy can be deposited on a chilled band to reduce the temperature quickly. However, if the candy is too cool it becomes unworkable.  "In practical terms, cooling of the flavored candy mass does not have a large impact on the flavor," notes Chris McIntyre, industry manager for confectionery, bakery and cereal, Crompton & Knowles, Mahwah, NJ. "Once you have blended in the flavor, with the more modern processes, the manufacturer starts feeding it through the rollers right away. As soon as the piece is partially solidified, you've basically encapsulated the flavor."  Cooking under vacuum reduces the temperatures required for boiling, and most newer equipment takes advantage of this. A 30-in. vacuum can lower the cook temperature required for an atmospherically boiled hard candy from 315 degrees Fahrenheit to 245 degrees Fahrenheit. This technique retains many volatiles lost at higher temperatures. Lower temperatures help eliminate scorching and the resulting off-flavors that can occur in candies made with dairy protein, such as caramels.  The flavor itself can be designed to withstand the designated heat levels. Flavors with low-flash-point components, like the esters that characterize many fruits, tend to volatilize more readily than others. Sometimes flavor overages are used to compensate for flavors lost through volatilization. While this may work in some cases, it is not always the right solution.  "You have to be careful as you increase the level of flavor, because flavor components flash off at different rates," says Robert Barrera, manager, flavor applications, Bell Flavors, Northbrook, IL. "That could throw the flavor off balance as you increase the level."  The type of solvent system used for the flavor affects the degree of flash-off. The more volatile a material is, the more likely it is to strip out flavor as it flashes off. Oil-based systems tend to be more stable than water-based systems. Alcohol is particularly subject to volatilization. Glycerin and propylene glycol may be stable at elevated temperatures, but they can create problems in the process and the finished product due to their humectancy. Flavor companies typically tailor the system used based on the process conditions.  Most flavors are added to the required solids after cooking. Both the flavor and solvent system should be low in moisture, or they might significantly affect the moisture and subsequent quality of the finished candy.Beat the heat  Flavors are subject to other heat-related problems. Some undergo chemical changes. These reactions may reduce the intensity, or form new compounds that contribute unwanted flavor notes.  "High heat can cause flavor changes, but you can't always anticipate them," says McIntyre. "You need a flavor that is very heat-stable. The chemical changes that occur can be both degradation or interactions between ingredients and flavors that would not occur at lower temperatures. Any of these interactions depend on what exactly you are doing. In some cases you have protein or fat present, which can lead to problems. It's more difficult to predict exactly how flavors react in a complex system and often more complex to solve, especially if you are trying to create a distinct flavor."  Flavor houses can engineer flavors to overcome some of the effects of heat. Higher levels of components subject to volatilization or dissipation can be added to maintain the desired profile. Less stable compounds can be eliminated or replaced with more heat-stable versions. Reaction flavors can be designed so exposure to heat creates an acceptable flavor. However, the temperature and duration of heat exposure must be controlled to guarantee the desired result.  The most common heat-induced reaction is the Maillard reaction, or non-enzymatic browning. When amino acids (protein) and reducing sugars (dextrose or glucose and fructose) are heated, they form compounds that cause visual browning and "brown" or roasted flavor notes. This is how the flavor of certain confectionery products, such as caramels and toffees, develops. These flavors may fit in certain applications, but they may come across as off-flavors in other products, such as those with a fresh fruit profile.Other undesirables  Besides heat, other culprits can cause flavor deterioration. Confections -- especially those containing nuts or vegetable oils, such as nougats or confectionery coatings -- often experience oxidative rancidity. This occurs when unstable free radicals in the fat react with oxygen, initiating a series of chain reactions. These reactions form various aldehydes and ketones which are responsible for the flavor problems. High temperatures, in both process and storage, accelerate oxidative rancidity. Once the reaction is initiated, it cannot be stopped, only slowed through the use of antioxidants. Although flavors often contain antioxidants to extend their shelf life, the level is insufficient to protect the finished product.  Essential oils are also subject to oxidation. This reduces the shelf life of the flavor itself and the flavor of certain confectionery products. While a glassy hard candy matrix largely protects the essential oil from exposure to oxygen, others do not. Marshmallows, creams and other aerated products incorporate air, exposing susceptible flavors to oxygen. Oxidation of essential oils tends to result in typical soapy notes. Citrus essential oils are particularly subject to oxidation and the formation of terpenes.  "This is one of the most critical stability issues in the flavor industry," notes Birgit Mitsch, business unit director, confectionery group, Firmenich, Princeton, NJ. "When a citrus flavor becomes oxidized, it develops objectionable off-notes in the flavor and in the finished product. Because of this, a standard citrus liquid or powder flavor has a shelf life of only one year. Certain encapsulation processes can protect flavors from oxidation."  Encapsulated flavors can offer protection from heat, but the encapsulating material often limits their use. Also they, as well as other dry flavors, can cause problems in certain applications.  "Dry flavors don't offer too many advantages except in chewing gum and possibly tabletted products," says Lynch. "Often moisture attacks the coating. Another problem with putting dry material in a confectionery product is graining -- the crystallization of sucrose. In a hard candy added dry material acts as a seed and decreases the shelf life by forming unstable crystals."  Other problems may arise with flavored confections, according to Lynch. Aldehyde flavor compounds may react with amino acids. Gummy candies can lose flavor over time because the protein in gelatin can bind or interact with these flavors. Low-molecular-weight flavor compounds can become entrapped in the helical structure of the amylose molecule that makes up starch, an ingredient often used as a stabilizer in gummy or jelly-type candies. Flavor perception can be influenced by the matrix, especially by fat or lack of fat.  A growing number confectionery products replace sugar with polyols such as xylitol, often in combination with high-intensity sweeteners. These types of candies may become more popular as the market shifts to consumers who want to limit their sugar intake for health reasons. Since the FDA has not contested requests for lowered calorie claims on these ingredients, they also can play a role in reduced-calorie candy formulations.  We discussed the flavor ramifications of using alternative sweeteners in the August 1995 issue of Food Product Design in "Achieving Flavor Parity with Alternative Sweeteners." Certain aspects relate directly to their use in candies.  "Flavors have to be formulated to go with a particular sweetener," says Lynch. "The polyols aren't as sweet as sugar. You can add a high-intensity sweetener, but you have flavor issues. You tend to use more flavor in products made with poly alcohols than in products made with sugar. The poly alcohol candies have to be produced at lower moisture contents than those with sugar because they have a lower viscosity at the same moisture content. You have to cook much higher and the resulting hard candies actually dissolve a little slower, diminishing the flavor release. Therefore, to get the same intensity you have to use a little more flavor in the product."  Polyols exhibit different sweetness levels and profiles, and even different flavor notes than sugar. Some polyols, such as xylitol, will produce a cooling effect.  "Using flavors in these products is almost case by case," notes McIntyre. "Some polyols produce particular flavor characters, and you may need to add a masking component in the flavor to cover that or to compensate for the cooling effect. You really need to compensate for the differences in the base. My advice would be to try your existing flavor, but to expect that it will have to be different."Different delicacies  Other processes can influence the type of flavors required. For example, the panning process forms a sugar shell by building up layers of sugar syrup and other ingredients. One of the problems is how to apply the flavor for consistent, even coverage. Typically, panning is done in an environment controlled for humidity and temperatures.  "You need stronger, concentrated flavors to reduce the panning time," says Barrera. "Otherwise you would keep panning forever to get the flavor level required. You could reduce the amount of flavor needed by using an atomizer to spray the flavor into the pan periodically so it is dispersed evenly over a period of time. In most cases you will be using a liquid flavor in a panning process. You can use a dry form with certain kinds of coatings, like a shellac coating."  Generally only one flavor is used, although the base candy may contain a different flavor. Different flavors can be applied to successive layers, especially if the product contains many layers, like a jawbreaker. That method would produce different flavor effects as the different layers melted in the mouth. With a thin-shelled product, adding flavor near the end of the process so it is near the surface may provide a greater flavor impact.  Among all the confectionery products, gum uses the most sophisticated flavoring systems. It is the main application for encapsulated flavors in confections. They provide prolonged flavor release, as well as extending the flavor's shelf life.  "Encapsulation is widely used in the chewing gum industry to control flavor release," notes Lynch. "It's usually a system consisting of dry flavor, liquid flavor, and other encapsulated materials such as sweeteners. The purpose of the system is to give you high impact up front and then longer lasting flavor. Some of the flavor is bound up in the gum base and released slowly. Some portion is released up front with the sugars when you first chew the prouct."  To extend their duration, flavors are encapsulated in water insoluble materials such as resins, lacquers and gum-based waxes. Shear produced by chewing breaks down the encapsulates and releases the flavor. A readily soluble dry form gives immediate flavor release, even before the gum is softened by chewing. This flavor can be mixed with the dusting agent applied to the gum's surface to prevent sticking.Attractive additives  One popular trend is the use of fruit juices or other fruit ingredients in confectionery products. Excellent products can result from their use, but several issues need to be addressed. First, juice contains a high percentage of water, so the preferred form would be a concentrate. These still contain a fairly high moisture level, so depending on the amount and the finished product moisture requirements, concentrates often must be cooked with the syrup, not added at the end.  "You must watch out for changes induced by the heat when using fruit juices," McIntyre says. "You can develop reaction notes that can come across as bitter or as an overcooked fruit note. The other point concerns what I would call fingerprinting or interleaving. You get a certain amount of flavor from the fruit or the juice. The role of the added flavor is to boost and complement the flavor notes that come through with the juice, so you may want a little different design in flavors you use with fruit."  The actual flavor impact depends on a number of factors: the type of juice used, the level, and the characteristics of the finished product. Fruit juice used in a hard candy probably would result in a minimal effect on the finished flavor since the levels are typically low -- 5% to 10%. A chewy type might support a little more fruit loading and the cook process is less severe, so more of the fruit character may come through.  Another ingredient that greatly affects the flavor of confections is the acid, especially in any kind of fruit candy. The candy industry commonly uses citric, malic and, to a lesser degree, tartaric. Some use phosphoric if it provides the right character. Most flavors will benefit by pairing with a specific acid for flavor enhancement -- citric for lemon, malic for apple. However, most manufacturing operations use one type of acid or a single blend for all products for economic or logistical reasons.  "Flavor, sweetness and acidity. Those three variables give a candy its unique character and primary taste appeal," explains McIntyre. "You can get sophisticated and measure sweetness/acid ratios, but in reality it comes down to choosing the optimum between the acidity level and the flavor impact. Acid brings the flavor to life. Strawberry without acid wouldn't appeal to anyone. Put enough in so it gives you a salivation effect and the right acid notes that one naturally associates with the fruit."  High acid levels create a sour, puckering effect currently popular in some candy. In most cases, the designer rarely adjusts the flavor or the flavor level. The taste buds are almost anesthetized by the extreme acidity. The flavor comes across as secondary to the acid hit.  Other ingredients may modify the flavor of confectionery products without contributing a specific flavor. Maltol and glycyrrhizin compounds potentiate sweetness and help to enhance the flavor of sweet goods. While they can contribute flavors of their own, often described as fruity and licorice respectively, generally they act as flavor enhancers. Additionally maltols can mask bitterness and off-flavors as well as supress acid bite.Just good taste  Natural flavors are in high demand in the candy industry, as well as elsewhere in the food industry, for their positive contribution to the label. But in confections, natural flavors can have a number of implications that make development more difficult.  "You get many advantages with artificials," notes Barrera. "The range of chemicals available is much greater and they are usually cheaper. You can be much more flexible with the design of the flavor in terms of usage level, solubility. If the manufacturer can only use oil soluble flavors, it's usually easier with artificial flavors. If they need a specific usage rate, an artificial makes it easier to adjust to that restriction. It's not impossible with naturals, just more difficult."  Natural chemicals are the same as their artificial counterparts. Their characteristics are identical. They have the same flash points, and they even have the same FEMA number.  Currently flavor companies can produce a wide range of natural aroma chemicals. While these are technically feasible, they often cost more to make because the chemicals are isolated by physical means to meet the definition of natural. Natural lactones are very expensive, for example. These are used in coconut, butter or other dairy flavors. Though the compound may only be used at a parts-per-million level, working with several of these compounds quickly raises the cost of the flavor.  The biggest benefit of natural flavors is the use of "natural" on the label. But the wording may change, depending on the actual flavor used.  "Natural fortifiers are compounded flavors made with all natural ingredients that you can add on top of juice-based candy," says Barrera. "The fortifiers survive the high heat for a longer period of time than the flavors from the juice. However, they might not produce the label you are looking for -- for example, 'natural strawberry.' A fortifier is not compounded with only ingredients isolated from strawberries, so it would be considered the ONF part of a natural WONF (with other natural flavors) flavoring system."  Regardless of the type of flavor used, flavor balance is important. Companies want increasingly stronger, more intense flavors. In some cases, merely increasing flavor levels produces the right impact. But just as often this upsets the balance.  "There comes a point where just increasing use levels has a negative effect," says Lynch. "If they are using 0.1%, customers often try to double it, but flavors have an optimal threshold. If you go above that it distorts and takes on some unpleasant characteristics. If they want the effect of double the dosage, then we have to do a lot more formulation work to try to achieve that in a positive way."  Flavor blends, especially fruit, are gaining popularity in the candy industry. Combining flavors also requires balancing and optimizing. Initial evaluation often requires mixing standard single flavors; but, again, this technique may not provide the best option.  The first step for both blends and single flavors involves setting the target. With a blend, often the first flavor named becomes the characterizing flavor and the others modify the overall flavor. Sometimes an actual target can be found, but often no standard exists for a particular flavor blend.  "The more complex the mixture, the more complicated it becomes to get the right balance," Lynch says. "You don't always want the pure fruit to peak, creating two distinct flavors. In most cases you want them to blend so that a 'kiwi-strawberry' is a taste by itself. It's rounded and it doesn't have any strange notes from either side sticking out and causing problems.  "Balancing the flavor is mainly done by the skill of the flavorist and often by using sensory techniques to optimize the profile by quantitative descriptive analysis," Lynch adds. "That's an important tool for flavor development. Kiwi-strawberry is often a profile existing only in someone's mind and you need to put it down quantitatively somehow. Sometimes you will be able to get a target like 'Smucker's Strawberry Jam.' Then you have a known reference point. Sometimes you will have someone say they want a wild strawberry that's been picked from the southern Black Forest. No one has the slightest idea what that means so you have to be a little creative."Migratory Habits  Flavor migration can be a problem. It is prevalent in fat-based confections -- in chocolate/peanut butter cups, for example -- where the flavor of the peanuts permeates the chocolate over time. Yet, it can occur in other candies, as well. Essential oils can migrate if they are not somehow bound into the matrix. This could create a problem in mixed flavor packages of tabletted confections.  "Because many encapsulates have almost no surface oil, they can be used in applications where flavor migration is a problem," says Birgit Mitsch, business unit director, confectionery group, Firmenich, Princeton, NJ. "By using such a system, an orange-flavored candy will look and taste orange, even if it sits next to a mint. This is nearly impossible to achieve with a liquid system."  Flavor migration isn't confined to finished products. Sometimes it can create problems on the manufacturing floor. Mint and related flavors can cause production nightmares through cross-contamination. This can occur in storage, as well as in production.  "Mint, cinnamon and similar flavors are very powerful flavors," warns Michael Lynch, business unit director, Haarmann & Reimer Corp., Springfield, NJ. "If you are producing a mint flavor alongside another product, the mint can be a very strong contaminant. It can affect your other products and even your packaging. You can easily end up with a lemon mint rather than plain lemon, for example."  Another problem with these strong flavors arises when the plant has some sort of product reclaim system. They typically dissolve the candy back into a syrup and recook it. The syrup usually goes through an activated carbon filter to remove color and flavor. Even after filtration, mint products cannot go back into a general reclaim system because it is difficult it not impossible to remove the mint completely.  "Using mint with a high-heat process increases some of the handling hazards -- burning, itching, sometimes shortness of breath -- that can occur," adds Robert Barrera, manager, flavor applications, Bell Flavors, Northbrook, IL. "High temperatures often magnify those effects. When working with these it's better to have a closed system."Back to top