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Bar Talk: Fruitful Fill-UpsBar Talk: Fruitful Fill-Ups

September 1, 1999

7 Min Read
Bar Talk: Fruitful Fill-Ups

Food Product Design

Bar Talk: Fruitful Fill-Ups
September 1999 -- Design Elements Plus

By: Lisa Kobs
Contributing Editor
Lynn A. Kuntz

  Adding a fruit filling to a grain-based bar can give the product an added dimension by incorporating flavor, nutrition and all-around consumer appeal. But for the filling to fit the bill - or more aptly, the bar - it must be designed especially to fit this application. Most bars contain 30% to 55% filling, but they can go even higher, so formulating the right product is paramount.  Typically, bar manufacturers will purchase these fillings premade in bulk to streamline their operations. These can range from 5-gallon pails to totes that contain over 2,000 lbs., depending on the manufacturer's needs. The larger-size totes can save on packaging and labor costs by eliminating the need to dump and dispose of the innumerable pails needed for a typical production run.  But, no matter what the container used for the filling, its contents are essentially the same. The ingredient selection and formulation process depend on a number of factors, says William Graham, vice president, flavor business unit, fillings, at H&R Florasynth, Teterboro, NJ. Key factors include solids, water activity, pH, fat content, density or viscosity, price, process parameters (for filling, baking and cutting), and miscellaneous finished-product requirements.Picking fruit  The fruit used and the amount that goes into a filling depend on economics, label requirements and the characteristics desired in the finished product. Typically, the fruit source is a juice concentrate ranging from 60 to 80 Brix, or a concentrated puree. However, most other forms - fresh, dried, canned or frozen - can also be used to make a filling.   The fruit can consist of either 100% of the characterizing fruit, or it can contain bland, cost-effective blends, such as apple or pear, as extenders for more costly ingredients. "Typically the biggest cost contributor to these fillings is the fruit and the fruit content," observes Graham. "And the kind of fruit that's most expensive may fluctuate from year to year and within the season. People have to consider what labeling implications the amount of fruit and the type might have. Some people do it (determine fruit content for labeling) on actual fruit in the filling and some do it on a reconstituted basis; it depends on the individual company."  Because of the high solids and aw required, and as a result of the long cook process, most bar fillings have very little particle identity. Graham recommends apple for applications that require a certain amount of piece identity. "It can be used as a non-characterizing fruit to provide fruit particles in fillings made from soft fruit, like strawberry or raspberry, or in a product like mixed berry when there is no named characterizing flavor," he says. In berry products, adding a low level of seeds can also reinforce the perception of real fruit. However, Graham warns that the type of fruit used and the resulting particulate size might be dictated by process equipment. "Most of the filling is deposited through some kind of extruder restricted by a nozzle size, and you have to be careful not to plug that up. Also some lines have screens or metal detectors that keep them from using fillings with particulates."  The fruit may also need supplemental flavors. When fruit or juice is concentrated, its volatile flavor components distill off. This is packaged as essence that can be added back before cooking of the filling is completed.  Flavor is a critical ingredient, as it sells the product, says Arthur Redondo, director of filling and aseptic applications with International Flavors & Fragrances, Inc., Dayton, NJ. Shelf life, pH, titratible acidity, process conditions, price and the ever-present "natural" label all play important roles when selecting the flavor. Because fillings undergo a high-temperature cook and are typically baked after filling, added flavors need heat stability.Sweet success  Typically fruit does not supply sufficient sweetness, so sugars must be added. Sweeteners also provide an economical way to add solids.  Sweetener selection for the fruit filling is based on different criteria than those for the cookie crust, and a variety of sweeteners may be used. "Crystalline fructose lowers water activity, enhances fruit flavors, is highly soluble and imparts no undesirable aftertaste," says Doris Dougherty, food scientist with A. E. Staley Manufacturing Company, Decatur, IL. "Corn syrups, which contribute a high percentage of longer-chain-length saccharides, tend to produce fillings which are longer in texture, more sticky, and difficult to deposit. A less soluble sweetener such as dextrose or sucrose may crystallize out and cause grittiness when used at a high concentration."  The sweetener system also influences microbial stability and shelf life. In addition, the type and level of sweetener can affect the gelatinization or hydration rates of added starches and gums.  For calorie-controlled applications, fillings can be formulated with high-intensity sweeteners such as aspartame. Because these sweeteners do not contribute the solids or viscosity that come with sugar, low-calorie bulking agents, particularly polydextrose, can make up the deficit.Stable of stabilizers  Fruit fillings also require a thickener that imparts viscosity, and will withstand the high temperatures used to bake the bars. This includes a variety of starches and hydrocolloids, used either separately or in combination.  "Water-binding is critical in the control of bake performance and prevention of boil out. Bake stability is obtained through a synergistic effect of a combination of starches and hydrocolloids," says Redondo.  Factors for stabilizer selection include flavor release, process capabilities, appearance and clarity, eating quality and price. Hydrocolloid gums, such as pectin, have excellent flavor-release capabilities. Alginates, cellulose gums and carrageenan are also used. "Lower levels of starches are preferred because of their tendency to absorb flavor and inhibit flavor release," continues Redondo. "Fillings are formulated to hold up to processing methods. Fillings need to be bake-stable to withstand oven conditions and shear-stable for pumping and extrusion. Shear stability is accomplished through the use of modified crosslinked starches."  Fillers, such as apple powder, cracker meal or an insoluble fiber, also stabilize by providing added viscosity. They impact the filling's oven performance, texture, sweetness and price. Fillers are critical in delivering mouthfeel. "Apple powder is a very good choice because of its exceptional eating quality," says Redondo. "Fillers high in insoluble fiber will deliver a grainy texture, so soluble fiber is preferred." High-fiber fillers also boost nutritional appeal.Rounding out the lineup  "Color is usually achieved with FD&C colors to maintain filling appearance throughout the typical 9- to 12-month shelf life," says Redondo. Other products, such as high-fruit-content blueberry or cranberry fillings, can do without added color due to the high content of naturally occurring pigments.  Acidulants, such as citric and malic acid, control pH and titratible acidity, which are critical to the functionality of some stabilizers and discourage microbial growth. Depending upon the fruit type, they help develop flavor profile. Citric works in many applications, but malic acid's flavor might complement an apple filling, for example. Most fillings will have a target pH of about 4.0 to 4.2, but it varies with the acid taste impact needed or other customer requirements.  Fillings do not typically require preservatives, as they are microbially stable due to the combination of low water activity, high Brix and low pH. However, if needed, sodium benzoate can deliver a measure of added protection.   Manufacturers are also looking for fillings that incorporate vitamin, mineral or herbal fortification. But fruit fillings might not be the best carrier for some of these items. "Because of the high-temperature cook used for manufacturing, it's like adding flavor - you know you're going to lose some in the flash-off," explains Graham. "Then you take it over to the customer who puts it in a heated hopper for depositing, then runs it through the oven." Heat-sensitive vitamins or other ingredients won't do too well under these conditions. "We are looking at some forms of encapsulation, but that's a long-term project," Graham adds.  Even if today's fillings aren't always nutritionally supercharged, a sweet, fruity center still turns a grain-based bar into a treat. Matching the filling requirements to the product and process ensures that the development process turns out that way too. Back to top

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