Sugar in the Mornin'

Sucrose is the traditional sweetening ingredient for breakfast cereals, and it remains the most common sweetener used in internal cereal formulations. In cereals made by cooking whole grain, the sucrose concentration is often only around 3%. Here, the sugar is added primarily for subtle sweetness to counter any potential bitterness from the grain. It also can act as a flavor enhancer for the desirable grain notes.

  "There's very little functionality that you'll get from sucrose other than sweetness," says Robert Fast, president and owner, Robert B. Fast Assoc., Poultney, VT, a consulting firm specializing in breakfast cereal production.

  Because formulated cereals allow higher levels of sucrose, the effect on functionality is much greater. In these products, sucrose contributes flavor characteristics, and it can affect the texture and mouthfeel of the finished cereal. It also may affect how the grain's starch gelatinizes during production, as well as the surface porosity of the finished cereal piece.

  According to Fast, nonpresweetened, formulated cereals usually have sucrose levels ranging from 6% to 12%. A presweetened product's sucrose level may be anywhere from 6% to 20% sucrose.

  Two forms of sucrose are most commonly used in cereal production. The first is dry, granulated sucrose - preferably with a particle size equivalent to, or smaller than, "baker's special." The other is 67° Brix liquid sucrose. The liquid sugar often is preferred because it is easily metered into any cereal production system - whether it is into the cooking water for wholegrain production, the mixer for a compounded dough cereal, or the head of an extruder barrel.

Corn sweeteners differ from sucrose in that they predominantly contain dextrose which, along with fructose and lactose, is a reducing sugar that will undergo non-enzymatic Maillard browning reactions. Such reactions are desirable in breakfast cereal formulas to provide the golden color that is appealing to consumers. The heat generated in breakfast cereal processing, however, can easily cause these reactions to go too far and make a cereal that not only is too dark, but has bitter off flavors.

  On the other hand, corn sweeteners offer a cost-effective way to contribute sweetness. Some have higher sweetness levels than sucrose, while others actually contribute a synergistic effect with sucrose to produce more sweetness for the money. Cost constraints usually require product designers to balance the corn sweetener level to make the formula as cost-effective as possible without resulting in an undesirably dark product.

  When looking to achieve this balance, keep in mind that the Maillard reaction proceeds at a rate directly related to the water activity. Also, the reaction does not occur just during processing, and it may continue in the finished product. Carefully maintaining the water activity of the product during processing, packaging and distribution can help slow the browning and allow slightly higher corn sweetener levels. Admittedly, breakfast cereals are pretty much a low-water-activity product, but small variations may make a big difference when the total production volume of a cereal is taken into account.

  The most common corn sweeteners used in cereals are regular corn syrup and high-fructose corn syrup. The production facility must be able to meter these liquid sweeteners accurately in order to maintain the delicate cost/color balance.

Other alternatives. Sucrose and corn sweeteners don't necessarily dominate the field of sweeteners used in breakfast cereals. Invert syrup, for example, also is common.

  Made by hydrolyzing sucrose to its component monosaccharides (dextrose and fructose), invert syrup will undergo Maillard browning and contribute color to a cereal. This combination of dextrose and fructose also generates a sweetness higher than that of sucrose. Taken together, these qualities make invert syrup a useful tool in meeting the cost/ color balance.

  Crystalline fructose is another sweetener that may be used in cereals. It has sweetness synergy with other sweeteners, including sucrose, which may allow cost savings. It is, however, a reducing sugar and must be applied judiciously to avoid too much color development.

  Fruit juice concentrates are sweetening ingredients that many in the food industry consider "label friendly." For cereal formulations, their dextrose/fructose composition allows them to perform very similarly to invert syrup and corn sweeteners. The exact composition will vary slightly depending on the source fruit and the crop year. From an economic standpoint, the most cost-effective fruit juice concentrate to use also will vary from year to year depending on crop yields.

  "You also can use some of these as a replacement for dry sugar," suggests Scott Summers, manager technical services, TreeTop Inc., Selah, WA. "Use 1.4 lbs. of a 70° Brix concentrate in place of 1 lb. of dry sugar. The water content should be reduced by about 0.4 lbs. to compensate for the additional moisture you've added to the system."

Putting sweeteners to work

  Sweeteners in the formula not only affect the finished product, they also may dramatically influence product behavior during production. In the case of extruded products, this behavior will even determine equipment design - especially at higher sweetener levels.

  Sweeteners affect the physical and chemical properties of extruded cereal products because their hygroscopic nature causes them to compete with starch for the available water. The extent of this competition varies depending on the combination of sweeteners involved, but certain effects are generally observed.

  First and foremost, sweeteners competing for available moisture in the system tend to inhibit starch gelatinization. This alters the cooking requirements for the cereal mass and reduces the viscosity of the mass, affecting the extruder's drive power requirements. By holding onto moisture, sweeteners also inhibit moisture release. This tends to hamper the product's ability to expand.

  To assure proper starch gelatinization, the residence time in the extruder barrel can be increased and/or the process temperature can be raised. Higher temperatures also help restore proper product expansion. Both of these features can be compensated for by adjusting the screw design. High-sugar products ordinarily are made on extruders equipped with screws specifically designed to cook and expand the product properly.

  Sweeteners will affect processing when cooking whole grains for flaking, puffing, shredding, etc. As with extrusion, sweeteners will compete for moisture and create the need either to increase processing temperatures or extend cooking times in order to gelatinize the starch properly in the grain.

  Sweeteners can make the grain mass sticky and difficult to machine. This is particularly noticeable in flaking and puffing, where individual grain identity is a requirement. Few, if any, processing solutions for this problem exist, and stickiness is usually controlled by monitoring overall sugar level. The upper range of sweetener content will vary depending on the sweeteners and the type of grain being processed.

The outer fringes

  Because higher sweetener levels can create so many challenges in cereal production, the high sweetener levels desired in a presweetened cereal are usually obtained through topical application. Using a topical sweetener, though, doesn't necessarily preclude a designer from using sweeteners in the base product, as well. As is the case with internal sweeteners, a topically applied sweetener system's primary role is that of contributing sweet flavor to the product. Also as with internal sweeteners, topically applied sweeteners offer important functional benefits too.

Flavor carrier. Many breakfast cereal processes expose the grain or dough mass to high levels of heat and pressure. Consequently, flavors added prior to processing may deteriorate and either lose intensity or generate off-notes. A topical sweetener system can act as a flavor carrier in order to avoid this detrimental exposure.

  From both a sweetness and flavor standpoint, topical application has the advantage of allowing the flavors and sweeteners to dissolve more quickly in milk and present a more intense, up-front flavor impact. By being coated in sugar, the flavor components also are protected from oxidation over the shelf life of the cereal.

Fortification vehicle. In addition to causing flavors to degrade, heat and oxygen are enemies of many vitamins, such as vitamin A, vitamin D, vitamin C, and occasionally thiamine. Normally, heat degradation of vitamins is overcome by adding overages of these heat-sensitive nutrients. In cereal processing, however, the extreme conditions often make the necessary overages prohibitively expensive.

  "Many of the very sensitive vitamins cannot withstand the temperatures and pressure of extrusion," says Audra Davies, principal scientist, food ingredients/nutraceuticals, Watson Foods Co. Inc., West Haven, CT. "If you want any kind of recovery through the process, you have to apply the nutrients after extrusion."

  Topical sweeteners provide a vehicle to deliver these nutrients after processing and protect the nutrients from oxidation, which is also a problem for most heat-labile vitamins. This functional role for sweeteners is just as applicable to non-presweetened cereals as it is to presweetened. A gum arabic solution could be used as a vehicle for vitamin delivery, but sweeteners tend to be less expensive to use. Besides, the amount of sweetener actually applied is low.

  For example, a sweetener solution requires about 10% sucrose in order to provide oxidative stability. Most solutions for nonpresweetened cereals usually contain between 15% and 20% sucrose. Because these are applied at such a low rate (the nutrient concentration is relatively low), even a 20% sugar solution would only contribute about 0.5% sugar to the finished product.

  Two approaches are commonly used for fortifying presweetened cereals. The first applies a vitamin containing spray followed by a plain sweetener coating. The second simply incorporates the nutrients into a single coating spray. Although the second option seems more efficient, many manufacturers prefer the first because it minimizes confusion and the potential to double-fortify if the same line is used for both presweetened and nonpresweetened cereal products.

  In both cases, the majority of vitamins are put into the wet mass prior to processing. Only the most heat-labile vitamins are reserved for topical application. Keep in mind that the sweetener coatings themselves are exposed to a certain amount of heat. This is overcome by adding the vitamins to the coating right before spraying and allowing just enough time for proper mixing. In some cases, an overage of the vitamins is necessary, but it won't be nearly as dramatic as it would be if the vitamins were added to the cereal prior to processing.

Binder. Topically applied sweeteners can be used as binding agents to adhere dry ingredients - such as nuts, candy pieces, etc. - to the finished cereal piece. The dry items ordinarily are simply sprinkled on immediately after the sugar coating is applied.

Free-flow agent. Fruit pieces, such as raisins, may stick together to form lumps in the product. A light coating with granulated sugar is one way to help prevent this.

Surface-sugar selection

  As is the case with internal sweeteners, the functional properties of sweeteners used for topical application will vary. Consequently, the sweeteners chosen will be determined by the desired effect. For example, topical sweeteners can be designed as a clear glaze, a frosty layer, or a dusting of granules.

  "There are many variations of these systems," says Summers. "Typically, they're multicomponent systems that take advantage of synergies found by the addition of different types of sweeteners."

Sucrose is often the primary choice for surface applications for several reasons. It contributes a lower viscosity, making application easier. It is not a reducing sugar, so it creates fewer problems with excessive browning during the final drying stage. And it can crystallize into either a white, "frosted" surface, or a hard, clear glaze.

  It doesn't matter much whether the sucrose is from sugar cane or sugar beets. As with internally used sucrose, fine granulated forms may be used in some applications, but most processors prefer to meter 67° Brix liquid sugar.

Corn sweeteners are used to a lesser degree than sucrose in topical coatings because their reducing sugar content causes them to brown during the drying stage. Low levels of corn sweeteners, however, can help control the rate of crystallization and the crystal size in a finished coating. Consequently, low levels (1% to 8%, typically) are used in hard, clear glazes.

  Honey, fruit juice concentrates and invert syrup have the same browning effects as corn sweeteners and are used in much the same way in sweetener coatings. In addition to browning, high levels of any of these sweeteners can make a topical coating sticky.

Getting things covered

  Different formulas and techniques abound for creating topical sweetener coatings. These various methods exist primarily to generate different visual effects on the finished piece. For the most part, though, the basic ingredients are predominantly sucrose and water, which are mixed, heated and applied while warm just prior to the final drying stage.

  "Hot application is desired because you want to be able to flash-off the excess moisture quickly," says Fast. "The coating also will be at a lower viscosity so it's easier to distribute and obtain uniform application over the cereal."

  Most coatings are applied at a solids level of 80° Brix. They start as a more dilute solution and are run through a heat exchanger to pull water out. The process is reminiscent of candy production.

  The exact procedure for creating many sweetener coatings is either protected by a patent or is a closely guarded company secret. Some general procedures, however, are common. For example, a smooth, glassy coating is achieved by cooking the formula to a higher temperature and using a low level of either a corn sweetener or invert syrup to control crystal growth.

  Snow-like frostings are usually made from a solution of 85% sucrose that also may contain gelatin or some other hydrocolloid. This syrup is atomized onto the cereal before the final drying stage. The snowy appearance is directly related to the rate of crystal growth, which is controlled by the temperature of the solution, the velocity of the atomizer, and the ambient humidity conditions in the application area.

  A traditional crystalline surface is easily achieved by spraying a simple hot syrup solution onto the product surface, then dusting it with a blend of powdered sucrose and dextrose. This is then dried at a temperature low enough to prevent browning.

  A smooth, nonporous cereal piece generally requires a minimum of 15% by weight of topical sweetener in order to obtain a continuously coated piece. Puffed wheat and rice are usually very porous and require 25% or more by weight to compensate for the sweetener absorbed by the cereal. The shape of the piece, however, may have a greater surface area, so these figures are just guidelines. Some cereals may actually have an application rate as high as 50% if the piece is porous, has a large surface area, and if a high degree of visibility is required of the coating.

  On the opposite end of the spectrum, coatings designed to deliver vitamins to nonpresweetened cereals often require the distribution of just a few ounces of solution over as much as 100 lbs. of cereal. Fortunately, specialized equipment is readily available to meet this need.

  Sweeteners provide a great deal more to breakfast cereals besides making the milk taste sweeter. They help build crispy textures, contribute visual appeal, and help protect sensitive ingredients in both plain and presweetened products. Even though some consumers may wish for totally sugar-free cereals, they probably would have a pretty soggy opinion of such products.

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