In the Paramount film, "Willie Wonka and the Chocolate Factory," reclusive candy genius Wonka shows a group of amazed factory visitors his "world of pure imagination" filled with edible confectionery marvels. Like those visitors in the film, consumers also attach a certain sense of magic and wonder to confections. This isn't surprising, considering all of the many unique varieties of candy start our as a concentrated solution of sugar in water.
Unlike Willie Wonka, product designers don't have the talents of Oompa-Loompas -- Wonka's magical, mythical assistants -- at their disposal. So designers need an understanding of basic confectionery structure and technique to transform these simple ingredients into confectionery delights.
The primary ingredient in candy is sugar as sucrose. Turning the sugar into candy involves dissolving it in water, concentrating this solution through cooking, and subsequently allowing the mass either to form an amorphous solid or to recrystallize. Sugar's physical properties -- specifically its solubility and its effect on the water's boiling point -- are key elements in the candy-making process.
At room temperature, about 2 pounds of sugar will dissolve in 1 pound of water. At higher temperatures, more sugar can be dissolved in the same amount of water. Once dissolved, however, the sugar will elevate the boiling point of the water. The result of these physicochemical properties is a specific relationship between the solution's boiling point and the amount of sugar solids contained therein.
The first part of basic candy making, therefore, is cooking a sugar solution to a specific temperature to form a supersaturated solution with a known solids content. When this solution cools, the sugar's solubility decreases and the sugar crystallizes out of solution. The next part of making a confection is controlling how this recrystallization -- known as graining -- takes place.
Recrystallization is controlled by varying how the supersaturated syrup is physically treated while it cools. For example, suspending a length of string into the solution and letting it slowly cool undisturbed will allow the sugar to recrystallize into large crystals on the string to form rock candy. On the other hand, rapidly cooling that same solution with agitation will cause fine crystals to form and be suspended in a saturated sugar syrup to yield a fondant, the foundation of confectionery creme centers.
Simple agitation is only the beginning. Other variables can be introduced to control the size of the precipitated crystals and, subsequently, the mouthfeel of the resulting confection. Such variables might include seeding the solution with undissolved sugar crystals, changing the temperature at which agitation is begun, and adding invert sugar.
Seeding with undissolved crystals does more than accelerate recrystallization. The size of the added crystals serves as a pattern for the crystal size in subsequent graining and allows the formulator to control the finished particle size. Undissolved sugar also can inadvertently seed the solution, leading to undesirable crystal formation. This can be avoided by covering the cooking vessel for a period of time to allow condensing steam to dissolve residual sugar.
Varying the temperature of the syrup when agitation begins allows a great deal of control over grain size. To obtain larger crystals, agitation should begin at higher temperatures. Smaller crystals are obtained by agitating at lower temperatures. The extremes of this spectrum are usually avoided to prevent the finished candy from either being too gritty or lacking body.
Sucrose is a disaccharide consisting of one molecule each of glucose and fructose. Breaking this bond will yield a mixture of glucose and fructose monosaccharides known as invert sugar. When invert sugar is present in a batch of candy, it tends to reduce the grain size. At higher levels, the invert sugar can even prevent crystal formation to yield an amorphous sugar glass such as that of hard candies.
Designers can add invert sugar to candy in two ways. First, the cooking process itself forms invert sugar. The longer the cooking time, the higher the invert level. The cooking time can be extended by adding extra water to the batch, which will then require more moisture evaporation. In spite of careful ingredient measurement and process control, this first method is somewhat inconsistent because the conversion also is affected by pH. Any variations in the process water pH will change the amount of invert sugar produced from batch to batch.
The second method for adding invert sugar -- formulating with an amount of commercially available invert sugar -- allows designers to include the exact amount of invert sugar needed to control crystallization. The desired amount of invert sugar also can be obtained by using invert-containing ingredients such as corn syrup.
An ear full
Corn syrup is partially hydrolyzed corn starch in which the starch's long molecular chain has been broken into a variety of sugars such as fructose, glucose and maltose. The degree to which the starch is converted into a syrup containing these reducing sugars is that syrup's dextrose equivalent (DE).
"Corn syrup DE is critical in confections," says Ernie Symanski, senior food technologist, Givaudan-Roure Corp., Clifton, NJ. "The higher the DE, the sweeter the syrup is. The lower you go, the more viscous it is."
Higher DE corn syrups also tend to pick up moisture more quickly and increase browning, and they are better at preventing crystallization.
Three types of corn syrups are used most frequently in confections: 42 DE, or regular corn syrup; 62 DE, or high-conversion corn syrup; and high-maltose corn syrup.
"Generally, the regular corn syrup is used in high-cooked confections like caramels, hard candy or taffy," says Carl Moore, research scientist, A.E. Staley Manufacturing Co., Decatur, IL. "Here you want products that are generally chewier, have a low moisture content, and must be resistant to sticking and moisture pick-up."
Soft candies such as marshmallows or nougats require tenderness rather than chewiness. These call for high-conversion cam syrup, but product designers shouldn't choose the corn syrup based on dextrose equivalent alone.
"The dextrose equivalent is not representative of the carbohydrate profile, which is what really affects the product," says Scott Helstad, technical services manager, Cargill Corn Milling, Dayton, OH. "One may have two sweeteners with the same DE, but changing the carbohydrate profile will change their performance."
High-maltose corn syrup has a DE of 42 like regular corn syrup, but it is made through a special conversion process that favors the production of maltose over dextrose. The higher maltose concentration offers advantages in certain products. For example, high-maltose corn syrup has less of a tendency to brown when cooked at higher temperatures. It also produces a drier surface on hard candies, compared with regular corn syrup.
Suppliers can provide regular corn syrup and high-conversion corn syrup with different carbohydrate profiles.
Handling the variables
A confection still is nothing more than a blend of sugar and a corn sweetener. Depending on the proportion of sugar to corn syrup, the type of corn syrup, the cooking temperature and the physical handling of the prepared syrup, however, these basic ingredients can form a tremendous variety of finished products.
While the foundation of a confection is formed by the sweetener selection and subsequent handling, the variety of confections is further expanded by including other ingredients such as fats, proteins, flavors, colors and stabilizers. All candies can be categorized into four basic types.
Ungrained confections are candies in which the sugar isn't crystallized, but forms an amorphous mass or glass. These include hard candies, as well as chewy candies such as taffy and caramel.
Hard candies start with a basic sugar/corn syrup blend cooked down to around 2% moisture and blended with flavors and colors. Varying the ratio of sweeteners produces different textures and different stability.
"A hard candy with a high percentage of sugar will be sweeter, but will have a shorter shelf life because it will start crystallizing on the shelf," says Symanski. "A higher percentage of corn syrup will be more stable because it will not start to grain."
The corn syrup percentage also can be limiting because levels that are too high may produce a candy that is too sticky or not sweet enough. If this is the case, other ingredients may provide a solution. If, for example, a certain level of sweetness in the hard candy requires more sugar and a long shelf life, a hydrocolloid might be added to control crystallization.
"Gum arabic can prevent or retard the crystallization," says Florian Ward, director of research and development, TIC Gums, Belcamp, MD. "It immobilizes the water so it doesn't migrate and cause recrystallization."
Cooking the sweetener blend to a moisture level between 3% to 15% forms the basis of a chewy non-grained candy. Cooking to these higher moisture levels will not favor the production of invert sugar, as is the case with hard candies. As a result, the addition of corn syrup is critical to prevent undesired graining in chewy candies.
"The key to doing this is the corn syrup/sugar ratio," says Robert Bianca, R&D section manager, Kraft Food Ingredients, Memphis, TN. "The more sugar crystals you have, the tougher and grainier the candy is. The more corn syrup, the chewier it'll be."
As with hard candies, chewy candies like taffy require little more than the addition of flavors and colors to the basic sweetener syrup. Caramels, on the other hand, require milk and fat in the formula to provide flavor and color. Here, again, the corn syrup selection is critical.
"In caramels, the Maillard reaction that goes on with the reducing sugars and milk proteins is important for developing both flavor and color," says Helstad. "The higher the amount of reducing sugar -- higher DE -- the more accelerated the Maillard reaction will be."
If a designer is formulating a caramel with a 42 DE corn syrup and finds that more color development is required, for example, it may be wise to switch to a high-conversion corn syrup, or even to add a small amount of dextrose or high-fructose corn syrup to the formula.
"That will accelerate the reaction and give you a darker piece," says Helstad. "They don't want to cook the caramel any longer than they have to."
Grained confections include products such as pillow-shaped after-dinner mints, fondants/creme centers, and fudge. Grained confection formulas are similar to those of chewy candies. To promote crystallization, however, the formula must have a higher level of sugar solids and the process usually includes agitation. The properties of the sugar and the processing parameters that affect graining already have been discussed.
Jelly candies, such as gumdrops, include starch, pectin or gelatin in the basic formula to achieve yet another unique candy texture. Although texturizing ingredients play the lead role in creating jelly candy texture, sweeteners are powerful supporting players.
"The DE of the corn syrup can have a strong influence on the gelling agent's ability to form cohesive gel networks," says James Carr, Ph.D., technical director, Systems Bio-Industries, Food Ingredients & Additives Group, Waukesha, WI. "In a gummy bear, higher concentrations of longer molecular weight carbohydrate polymers can cause phase separation."
Studied microscopically, such a phase separation might be seen as small gelatin droplets separated from the carbohydrate polymer continuous phase. In general, using a higher DE corn syrup -- 62 DE, rather than 42 DE -- will reduce the chance of this occurring. But relying solely on DE can be just as unsuitable as it is with other confections because the carbohydrate profile of the corn syrup still may include significant amounts of the higher molecular weight molecules, even at a higher dextrose equivalent.
Important as sweetener selection is, designers can obtain the most flexibility in jelly candy texture through the selection of the stabilizer system.
"Other things in the formulation are important, but the type of gelling agent you use will make the biggest difference," says Symanski. "A gum-based jelly will be chewier, while a starch jelly will be shorter. But it also will be stickier. Pectin jellies aren't used too often, but they make a high quality jelly with a good texture and good flavor release."
A typical starch-based jelly candy is the gumdrop, where the expected texture comes from using thin-boiled starches that have been modified to function at a high solids level. Other variations of the starch can fine-tune the product texture.
"Depending on how firm a candy you want, you can increase the high-amylose portion of the starch content," says Eric Shinsato, senior food technologist, American Maize-Products Co., Hammond, IN. "The typical texture and bite of a gumdrop comes from a combination of about 25% high-amylose and 75% common starch. If you want a firmer texture, you can increase your amylose content."
Gelatin-based jelly candy has a more elastic texture than that of starch-based products. The gelatin-based jelly candies also exhibit greater clarity.
"The gelatin normally used has a medium to high bloom, or gel strength," says Carr. "But a wide range of textures can be generated using either lower concentrations of a high-bloom gelatin or higher concentrations of a low-bloom. The former gives a more tender, short texture, while the latter gives more of an elastic, chewy texture."
Pectin jellies have their own unique texture which consists of a relatively soft bite with a short texture and rapid meltaway. Designers must be aware, though, that pectin is more expensive to use than starch or gelatin. Consequently, pectin is used more often in higher priced, premium jelly candies and centers.
As far as processing is concerned, pectin-based jellies must have a pH within a certain range in order for the pectin to become functional. For fruit snacks and other fruit juice-containing jelly candies, pectin's need for an acidic environment is an advantage.
"In pectin confectionery, pH control is more of an issue in achieving proper gelation, in contrast to starch and gelatin where it has less of an influence on the network development," says Carr. "In all cases, though, pH and acidity must be considered because carbohydrates can hydrolyze during long cooking processes at high temperatures if the environment is acidic. The acid is usually added last in the process to reduce the contact time."
While starch, gelatin and pectin offer a range of potential textures for jelly candy, combining these ingredients gives designers even more specific control over texture. Gummy candy, for example, is traditionally made with gelatin. Because of gelatin's low melting temperature, these candies may not have enough heat stability for distribution in warmer climates. Combining gelatin with a slow-set pectin can raise the melting temperature and improve the heat stability. Combinations also may include other texturizers such as gum acacia and agar.
Aerated confections comprise a large group of products ranging from nougats to Marshmallows. This category is unique in that it combines elements of all the other basic candies. Aerated confections, for example, can be based on a syrup mixture that is either ungrained or grained. Like jelly candies, aerated confections also frequently contain stabilizers to contribute texture.
Although the finished product range is broad, these candies are unified by the fact that they all require the incorporation of air into the basic sweetener syrup matrix during processing.
"Aeration itself provides a shorter texture, modifies mouthfeel, reduces stickiness of the product, and results in an overall decrease of perceived sweetness," says Carr. "Aeration is normally achieved through one of two means: chemical or mechanical."
In chemical aeration, the candy will contain ingredients such as sodium bicarbonate to leaven it like a baked product. In mechanical aeration, the formula will contain a foaming agent and/or a stabilizer, and it will have air incorporated using a planetary mixer or a continuous pressure beater.
"Aeration under pressure is the typical industry standard for production of aerated confections," says Carr. "It provides shorter beating times, easier transfer of the material, better homogeneity and better consistency. If the confection contains high levels of fat, you also can mix in inert gasses to inhibit oxidation."
Because aerated confections may be either grained or ungrained, their sweetener blends can be quite different from one another. Marshmallow provides a good example because it is made in both forms. The traditional marshmallow is ungrained, while "Circus Peanut"-type products are actually a grained marshmallow.
A traditional marshmallow might contain about 60% corn syrup, 30% sugar, and 1 % to 2% gelatin. The corn syrup/sugar ratio here will provide only about 35% to 40% solids in order to prevent crystallization. Crystallization can be further avoided with proper selection of the corn syrup type. A higher conversion corn syrup will contribute more invert sugar to the formula, which inhibits crystallization.
"For a grained marshmallow, you simply increase the sugar ratio to the point where it will crystallize about 60% to 65%," says Moore. "Then you whip it and seed it with a little powdered sugar. As it cools, the sugar crystallizes out to form the grained marshmallow."
Designers also must select the right aerating agents, which often are protein-based ingredients such as egg albumen and soy protein.
"You want to select aerating agents that give you the type of body texture and shelf life you're looking for," says Bianca. "If the end application needs a long shelf life but is a high-moisture system, then the selection of aerating agents will dictate one path. If it's going to be a dry product you will have a different situation."
In addition to proteins, stabilizers often are blended with aerated confections. Gelatin, in particular, is useful because it offers many functional properties.
"Gelatin is a key stabilizer in this application,' says Carr. "It functions as a foaming agent because the presence of gelatin decreases surface tension. It functions as a stabilizer because it gives the cell walls resistance to deformation and maintains the structure. Gelatin's water-binding capabilities also help to increase shelf life."
Building from the basics
Basic confections have a long tradition, and many still enjoy strong consumer popularity. Most newer confections designed for the mass market are created by combining the basic forms. A Milky Way bar, for instance, is an aerated nougat topped with a non-grained caramel, and the whole thing is enrobed in chocolate. However, this doesn't mean product designers should get carried away creating all sorts of wild combinations when developing prototypes.
The most important thing in new product success is a cord of familiarity," says Anton Angelich, business director, sweet goods, Givaudan-Roure. "People will try exotic things, but they need to relate back to something they're familiar with."
Still, consumers have accepted some new combinations. Kit-Kat and Twix bars, for example, were the first products marketed as confections in which cookies were used as a component. Now, using cookies and cookie pieces is common in confectionery products.
Combining different components isn't always easy. Different components of a multi-component confection may have different moisture levels, leading to moisture migration. A grained confection may come in contact with a non-grained one and cause it to crystallize.
Fortunately, corn sweeteners again may provide a solution. Designers can alter the moisture-holding characteristics of basic components by selecting a corn syrup with a different DE. The same method also can be used to adjust resistance to crystallization.
Confections under cover
Reducing interactions between the various candy components isn't the end of formulation challenges. Interactions also must be minimized between the various components and any coating applied to the confection. Confections frequently are covered with chocolate or a hard, sugar-based shell. The characteristics of the base candy directly affect the quality of the finished confection.
Panning is a process by which a thin layer of chocolate or a hard candy shell is applied to a candy or nut base. The base material is first placed in a large, rotating pan (hence, the process name). For a hard shell, several layers of sugar syrup are sprayed into the pan and allowed to dry between applications. Chocolate panned candies replace the sugar spray with chocolate. Again, each layer is allowed to set between applications.
To be successful, the base material must be sturdy enough to withstand tumbling in the rotating pan. This doesn't mean being able to withstand just a little bit of jostling. Some panned candies have as many as 40 thin layers of coating. Considering the drying/setting time between each layer, it's easy to see how tough the base candy for panning must be.
Another important characteristic for the base material is that its structure must be stable when exposed to moisture. The sugar solution used when applying a hard candy shell usually contains a fair amount of moisture. In other panning methods, the base material is sprayed with water and dry sugar is added. With either method, the base piece must maintain its integrity when exposed to moisture.
Chocolate panning places other demands on the center to be coated. These requirements are the same for pieces that will be enrobed. First, the center to be covered in chocolate must have a certain degree of rigidity in order to accept the coating and stand up to the weight of the chocolate. This rigidity must be maintained to temperatures as high as 120 degrees Fahrenheit -- the maximum temperature for chocolate application. If the center melts below this temperature, adding molten chocolate to the rotating pan will turn the centers into an amorphous glob. In an enrober, such centers will simply disintegrate and vanish under the chocolate waterfall.
"Even the soft cherry center of a cordial has to be hard enough to start with," says Ed Minson, Ph.D., director of research and development, Ambrosia Chocolate, Milwaukee. "You can liquefy the center with enzymes after enrobing, but it has to be hard enough to accept the coating initially."
Centers that soften or liquefy during the distribution cycle require that the confection have a fairly thick coating of chocolate with even coverage. This assures that the liquid center won't leak out of the product.
Another characteristic of the center to consider is its moisture. Chocolate has very low moisture levels -- almost always lower than the moisture level of the center. This can result in moisture migration to the coating, which can cause sugar bloom.
"If you have a higher moisture center, you can seal it using a very thick layer of chocolate," says Minson. "You also may glaze it first with an intermediate layer. This will be some type of moisture-inhibiting substance such as confectioner's glaze, or shellac -- typical ingredients used on panned products."
Some designers may try to control moisture migration using a water-binding substance such as starch in the center formula. This isn't necessarily an appropriate solution.
"Confectionery centers are mostly sugar with high solids and little water," says Shinsato. "If you put a starch in and bind what little water is there, the center won't be as flexible. It might have a more crumbly texture and a drier consistency."
Fat can migrate from the center to the coating, too. This raises the issue of fat compatibility because the cocoa butter found in chocolate can bloom if exposed to incompatible fats migrating from the center.
"You need to know what impact the center could have on the coating" says Minson. "The fat from the coating also can affect the center -- whether it is cocoa butter or something else."
A final feature of the center to monitor is how much it may expand or contract over time. If this is significant, the coating may crack. Cracks make the confection look defective and may allow moisture to migrate in or out of the center if they are extensive.
If the center's tendency to expand or contract is significant, designers can take two primary approaches to avoid cracking. The first is to maintain even temperatures during production and distribution.
"If the center is being formed at very high or low temperatures, you'll want it to approach the enrobing temperature before actually coating it," says Minson. "If you have a very cold center, it will tend to expand as you warm it up to ambient or normal product storage conditions. If it's hot, it'll contract. You want the center to be around 75 degrees Fahrenheit to 85 degrees Fahrenheit -- something within a reasonable temperature range of the final storage temperature."
The other way to reduce cracking is to select a coating that is more resilient. Chocolates tend to be the least resilient, while non-tropical oil-based compound coatings tend to be the most resilient.
Whether you are selecting right sweetener blend to prevent crystallization in a hard candy or choosing a fat that is compatible with the coating in an enrobed piece, there is much more to creating confections than just boiling sugar water. At the same time, creating quality confections doesn't require magic. Knowing the mechanism behind basic confectionery structure can be the next best thing to having an Oompa-Loompa as a technician.