The body of this article was first published in the February and December 2004 issues of Prepared Foods' sister publication, Dairy Foods magazine. It offers ways to avoid problems when working with inclusions such as syrups, nuts and confectionery pieces.--Eds.
Q: How do inclusions affect the quality of ice cream?
A: Inclusions add considerably to ice cream's sensory appeal. However, the use of both particulate and/or syrup inclusions must be managed properly to avoid serious negative effects on quality to both ice cream and inclusions.
Beyond the obvious negatives of using poor-quality inclusions, indirect effects on ice cream texture can be equally degrading. Inclusions added in “warm” will melt ice in the immediate vicinity of the inclusion. During hardening, water will deposit on existing ice crystals, increasing their size and the likelihood of coarse texture. Pre-chilling inclusions and lowering ice cream draw temperatures minimize this effect.
Injected syrups can be too thick or stiff, or too thin or stringy. It is important to balance desired eating quality and avoid “puddling,” which results when syrup migrates to the bottom of the carton. Syrups should be thick enough to minimize their flow properties in the ice cream, but not so thick as to cause other difficulties. High-viscosity syrups may or may not be responsive to shear thinning that occurs during injection. Such properties can be engineered into syrup formulations. Low ice cream and syrup temperatures also can be helpful. It is important to harden the ice cream rapidly, so that the ice cream freezes quickly, holding the syrup within the structure of the ice cream.
Negative effects of inclusions on ice cream texture can be minimized by encouraging the development of small ice crystals in fresh ice cream. These practices include increasing water immobilization in the mix, freezing to the lowest feasible exit temperature, rapid hardening and minimizing exposure to heat shock.
Particulate inclusions can have associated dust, which often contributes to sandiness by acting as sites for lactose crystallization. To minimize this, general tendencies for particulate inclusions to dust need to be known, and particulate handling should be managed to discourage dust development. Furthermore, particulates (or even syrups) that absorb water readily can remove water from ice cream and make the ice cream more vulnerable to sandiness by concentrating lactose in the vicinity of the inclusion. To minimize the general influence of particulates on sandiness, it is important to avoid high lactose levels in the mix used for such products.
Finally, when adding inclusions, keep in mind that ice cream is displaced and the weight of the finished product increases. Typically, an adjustment of ice cream overrun can maintain finished product weight. This, in turn, increases the ice cream's vulnerability to many of the effects already noted.
Q: How does ice cream affect inclusion quality?
A: Inclusions (both fluid and particulate) typically have lower moistures and lower water activities (Aw) than the ice cream to which they are added. This makes unfrozen water flow from ice cream to inclusion. Added moisture can make inclusions (depending on type) soft, mealy and/or thin with less bite, chew and/or crispness. Direct and indirect modification of flavor delivery is also possible. Loss of visual appeal--such as loss of inclusion integrity or loss of clear differentiation between the added inclusion and ice cream--may result.
Adding inclusions under conditions where limited amounts of unfrozen water are available preserves both ice cream and inclusion quality. Conditions include temperatures under which the inclusion is added, the temperature of the ice cream to which inclusions are added, physical abuse of the inclusion at time of addition, speed and temperatures of hardening, and thermal abuse of the finished food.
Particulate inclusions can be protected by modifying compositions (managing Aw) and forms (size and shape) or applying a variety of surface treatments. Managing composition and/or form can deter moisture migration. Water-free coatings, such as fats, oils, chocolate, etc., offer effective barriers to water transfer, but may change the eating quality of the specific inclusion. Hard candy coatings also can be used. These coatings typically have even lower water activities than the protected inclusion. Thus, candied inclusions tend to absorb moisture quickly and lose their desired eating quality more rapidly.
Injected fluid inclusions vary significantly in composition, color, density, viscosity and rheological properties. The amount, formulation and pattern of injected syrups can depend on the specific design of the injection device being used. Injector design varies greatly and can affect the conditions under which syrup is delivered into the ice cream. This, in turn, influences how water flows to the syrup from the ice cream and affects structural integrity and stability of the syrup, as well as that of the ice cream and ice cream/syrup interface.
Q: How are inclusions added to novelties such as cones, push tubes and sandwiches?
A: The addition of particulate inclusions into such novelties is limited by their relatively small size and the need to maintain specific shape identity in cones (particularly the round-top variety) and sandwiches. As particulates become larger, the number of particles in a given volume of ice cream becomes smaller. In other words, with novelties, which are typically small portions as compared to half-gallon cartons of ice cream, large particulate inclusions could be absent from some units altogether. Furthermore, large particulates tend to interfere with the uniformity of shape, which is important to cones and sandwiches. Thus, inclusions for novelties should be relatively small in size, so pieces are present in all servings and novelty shapes are not affected.
In the case of injected syrups, restrictions related to novelty shape and size, extrusion nozzle design and ice cream flow distort the distribution of any but the simplest of variegated patterns. These challenges can be overcome by selecting a relatively simple pattern injected relatively close to the filling nozzle.
For molded ice cream novelties, the injection of inclusions can be accomplished by using new bottom-up fillers available from some equipment manufacturers. Many times, these bottom-up filling devices can be retrofitted onto existing molded novelty equipment.
Q: Is there a way to treat sandwich wafers and cones to prevent them from getting soggy?
A: The migration of moisture from the unfrozen portion of ice cream into low-moisture, unprotected, hard-baked items like cones or sandwich wafers is unavoidable. Protection against moisture migration can be provided by coating the contact surface with a material impervious to water (e.g., chocolate or fat/oil coatings), yet compatible with desirable eating qualities. In the case of cones, this is accomplished effectively by spraying a thin film of chocolate coating inside the cone shortly before it is filled. Coating sandwich wafers in-line is impractical, and logistics or cost limitations work against the use of pre-coated wafers. In addition, the presence of a coating likely would make it necessary to change the methods of handling wafers, possibly reducing throughput and increasing breakage. The industry, more or less, has accepted the idea that in order to maintain cost parameters (with respect to wafer cost, handling and throughput), wafers inevitably will become soggy within a few days of manufacture. Apparently, consumers accept this condition as normal, as sales volumes for ice cream sandwiches seem unaffected by this apparent defect. Further, a crisp, stiff wafer can have problems as well, due to increased breakage during distribution and the tendency for ice cream to slip between the wafers during eating. Thus, a crisp, dry wafer may not be totally necessary or desirable.
Q: Why is gelato so rich-tasting and smooth, yet lower in fat and calories?
A: The International Dairy Foods Association Association (IDFA, Washington) describes gelato as a frozen dessert “…characterized by an intense flavor and served in a semi-frozen state. It contains sweeteners, milk, cream, egg yolks and flavoring.” The semi-frozen state mentioned in this description is a major factor in gelato's perceived richness. In that condition, gelato is served soon after it is frozen, so ice crystals have not had the opportunity to grow and produce coarseness. Also, gelato, whether served semi-frozen at retail or packaged for hard-frozen distribution, usually is produced with relatively low overrun, making it quite dense. This adds to the product's perceived richness. Flavors in such low-overrun, dense products often are deliberately more concentrated and intense, delivering flavor profiles not possible in more-conventional ice cream formulas and formats.
The characterization of gelato as “lower in fat and calories” is erroneous. There is no standard of identity for gelato, and fat levels in gelato vary as much as those in conventional ice cream. Also, the composition ranges involved are such that the calories per gram are in the same range as ice cream, per se. In fact, the lower overrun of gelato often produces higher calories per serving than conventional, high-overrun ice cream, because of the increased weight per serving associated with the lower overruns.
Showcase: Nuts and Fruits, and Inclusions and SyrupsBlueberries are easy to formulate for dairy products from ice cream, yogurt and frozen desserts to smoothies, drinkable yogurts and milkshakes. With their versatile formats--fresh, frozen, IQF, purees and osmotically preserved--they provide appealing color, lush flavor and intriguing effects like blue swirls and patterns. Blueberries are excellent as a topping or mixed into products. Consumers are aware of blueberries' high antioxidant level and healthy profile, and are looking for real blueberries in dairy products. U.S. Highbush Blueberry Council, Thomas J. Payne, email@example.com, www.blueberry.org
Apples, whether fresh, frozen or dried, are rich in a wide array of properties promoting good health. High in vitamin C, potassium and fiber, apples have also been proven to slow the oxidation process of LDL cholesterol. One serving of TreeTop's 100% apple juice provides 120% of daily vitamin C requirements, with no sugar added. Apple ingredients also are used in numerous food applications, from waffles to dairy products, adding flavor, sweetness, texture and antioxidant properties while replacing fat and reducing cost. TreeTop Ingredient Division, 800-367-6571, www.treetop.com
Why do top-selling frozen treats have names like Caramel Almond, Mocha Almond Fudge, Vanilla Swiss Almond, Cherry Almond Crunch and Amaretti Swirl? As an undisputed customer favorite, almond-enhanced ice creams and frozen novelties grab attention and drive sales. In 2004, almond-
primary product introductions climbed 30% to 215 (up from 167 in 2003), and new product introductions in desserts and ice creams soared 46% in 2004. A frozen dessert natural, few ingredients complement chocolate, fruit, coffee, caramel and other popular flavors as well as almonds. Add product versatility and convenience to the list (choose from an array of almond varieties, types and processing options), and you've got a winning formula. The Almond Board of California, Harbinder Maan, 209-549-8262, firstname.lastname@example.org
Kerry Sweet Ingredients appeals to the latest ice cream trends--namely, fruit flavors and indulgent taste combinations--with its Black Forest Cake frozen dessert flavor concept. Black Forest Cake features real cherries, decadent chocolate cake pieces and sweet chocolate sauce swirled in creamy cherry-flavored ice cream. Kerry Sweet Ingredients, Karen Holliday, 800-255-6312,