Crispy coverings with soft-and-chewy centers or smooth-and-tender outsides with crunchy bits inside—coatings and inclusions such as these help improve flavor and add appeal. On the outside, food coatings, such as a batter or breading in fried and baked foods, go beyond adding complex taste and texture components and contributing to aesthetics. They act as a barrier to mass transfer during frying, thereby reducing oil uptake and preventing moisture loss.
Today, practically everything—from nuggets to vegetables to wings—is breaded, battered, and glazed. Such treatments can add additional color, flavor, and texture and, sometimes, even add a boost in nutrition or extended shelflife.
This transformation of an otherwise simple food into a culinary delight, while seemingly simple, requires careful consideration of ingredient, process, and economics. Other key considerations include how the consumer will use it; and will it deliver its promise of a crunchy, crispy texture.
Working Class Heros
Coatings, batters, and breadings typically are crafted from a combination of flours or starch, water and seasoning. These seasonings run the gamut, from simple salt, pepper, spices, or herbs, to more complex flavor providers, such as cheese flavors, yeast flakes, MSG, and other flavor enhancers. They also can be made with or without a leavening agent or a binder (such as egg). The goal is to form a fluid batter or even breading/batter coating on foods.
Batters can either be made of adhesive semiliquid, into which food is dipped and subsequently coated with breading; or they can be tempura, which usually contains leavening substances and is applied solely to the food surface. Batter formulation is flexible, allowing for maximum adaptation to food product development.
The formulation, composition, physicochemical properties, and microstructural configuration of the components of batter and their relationships play a key role in product development and quality definition. Contemporary consumers have sophisticated expectations for variety and convenience that demand a better understanding of batters and breading systems. Improved functionality and quality, as well as cost-effectiveness with the use of new and clean ingredients that add further value, are top of mind for those in batter formulation.
Interestingly, there still are some unknowns in relation to the physical and chemical properties of batters in process, such as aspects and mechanisms of fat uptake, moisture loss, texture, structure, viscosity, thermal gelation vis their composition and formulation.
Crunchiness, inside or outside a product, has become an increasingly popular demand in recent years, no matter the type of food and whether savory or sweet. The desire for crunchy textures also is moving beyond the snack category to become the center-of-plate meal component. But, when it comes to including a crunchy outside or inclusion, ingredient functionality is critical to the transformation. For outside crunch, coatings must adhere and cover the product completely.
Battered and breaded foods must be crisp and crunchy, not oil-logged or soggy. Carrying and delivering flavors through the various preparation steps is a precision process with specific challenges at each step.
A current and almost universal trend is the use of protein-rich ingredients to deliver crunchiness to coatings. Recent advances in ingredient technology help processors meet emerging needs in battered and coated foods. This is especially true for the growing demands for healthier foods, higher protein, and accommodating allergy needs or preferences (based on both valid and perceived health benefits).
Pulse-based ingredients are thus finding their way into coatings and conclusions. They are high in protein, non-GMO, vegetarian, and often sustainably sourced. They also are of the “in the right place at the right time” ingredient category, in that the UN recently declared 2016 as the International Year of Pulses.
Give Peas a Chance
Pea and other pulse flours and proteins readily can be used to replace wheat and corn flours in coatings. Product developers are turning to lentils, fava beans, and chickpeas, because they are naturally non-GMO, gluten-free, low-allergenic—and are rich in protein, fiber, and a host of micronutrients.
Combined with starches and other non-gluten flours, such as sweet potato and quinoa flour, pulse flours and proteins serve to replicate the functionality and characteristic texture of wheat flour-based coatings, while also appealing to the health-conscious. Another advantage to pulse proteins is that they add to the inherent flavor of coated foods. They boost flavor profile authenticity in ethnic cuisines, such as Chinese, Indian, Mediterranean, and Middle Eastern foods. This is important from to both marketing and consumer acceptance.
Pulse ingredients are ideal for coatings because of their high affinity for water, high water-absorption capacity, and thickening effects that allow them to adhere to the product and act as a barrier to moisture migration. Pulse flours and proteins are particularly sought-after for the replacement of soy protein. They can be used to boost the protein content of breaded patties and coated nuggets destined for school nutrition.
With every bite taken of a breaded or battered product, the consumer makes an assessment of its texture, its crispiness, and its crunchiness—or, on the negative side—whether it is too crumbly or hard, or soggy and unpleasantly chewy. Each of these assessments determines the ultimate consumer satisfaction and, most importantly, whether or not the product will be purchased again.
“Each ingredient plays a unique and complementary role in delivering the perfect texture,” cautions Linda Malcolmson, manager of special crops, oilseeds, and pulses for the Canadian International Grains Institute in Winnipeg. She explains that, in many cases, formulating coatings and inclusions with alternate ingredients is not a simple matter of drop-in replacement of one ingredient with another.
Such formulations or reformulations require in-depth understanding of the role of the signature ingredient in the food product and the implications of the end-result on consumer acceptance and perception.
Ingredient science and technology is advancing the humble yellow pea into formats and functions where it previously has never been applied. One customized solution involves pea crisps made with pea protein, typically in concentrations of 35, 50, and 60%. They can be formed into nearly any number of shapes, including round, cylindrical, and prolate spheroids (football-shaped).
With the current trend toward allergen hyper-awareness, they have found strong favor as a non-allergenic, gluten-free nut replacement.
Pea protein crisp inclusions can help provide protein fortification and a crisp, crunchy texture in bars, cereals/granolas, and as toppers or stir-ins for yogurt and oatmeal. Such pea crisps demonstrate an ability to retain firmness longer than some carbohydrate- or nut-based inclusions and, thus, maintain the snap and crunch consumers find appealing.
Pea crisps toasted at the end of their complex processing steps are just right as a non-allergenic nut alternative in confectionery to provide a tender, sensual crunch with an appealing, mildly nutty flavor in products like pralines, brittles, chocolate bars, and clusters.
Guaranteed non-GMO in contrast to soy, the comparatively high content of complex carbohydrates and proteins of pea-based ingredients makes them a perfect fit for products destined for the health and wellness aisles.
Wave of the Future
In microwave cooking, heat is generated from within, as opposed to conventional cooking, where heat is applied from the exterior. Cooking or reheating of breaded and battered, coated products is problematic in microwave ovens, because heating the product from the inside generates steam, making the coating soggy. Conventional coating formulations are, therefore, unsuitable for use in microwave ovens.
Typical foods enrobed or wrapped in breadings and batters also are generally high in moisture. Classic examples are poultry, fish, pork, and beef containing as much as 60% water, with battered or breaded vegetables containing much more. Although part of the water is integrally bound as a component of the cellular structure, the remaining water is freely available and freezes into crystals when such products are frozen.
When a frozen product is heated in a microwave oven, the microwave energy is absorbed primarily by the frozen available water, then is rapidly converted into steam. This expulsion of water from the core product, in addition to making the coating soggy and unpalatable, also makes the core of the substrate dry—due to loss of water.
One solution to address the soggy coating problem is the use of a pre-dust before the application of the batter. In this case, formulating the pre-dust to selectively absorb the expelled water, without allowing it to make the coating soggy, is necessary. Pre-dusts, the primary interface between the foodstuff and the coating, are critical components in optimizing adhesion; preventing moisture migration from the interior after cooking and during reheating; and also for retaining and enhancing flavor without allowing it to dissipate into the cooking medium.
A recent approach to making crisp and crunchy microwaveable battered and breaded products (in combination with a succulent, moist core) focuses not on the breading and coating, as much as on the freezing conditions.
Reducing the core temperature of the fried, coated portion rapidly from when is still high reduces the formation and number of ice crystals. The result is fewer pockets of steam-generating crystals and subsequent release of excessive moisture near to the surface coating.
It is not crunch alone but also the sound that matter to consumers, according to Oxford professor and experimental psychologist Charles Spence, PhD. Sounds made during eating can modulate people’s perceptions of moistness, texture, and other aspects of food—and might influence taste perception. Just as a crunchy carrot is perceived to be fresh, the crunchiness of coated products has a unique impact on consumer perception of the quality and freshness of that food.
Spence cites such carefully researched products as PepsiCo./Frito Lay’s Doritos line, Procter & Gamble Co.’s Pringles, and Kraft Heinz Co.’s Corn Nuts brands as products that consciously were developed with reliance on intrinsic sound as a key marketable attribute.
Two other examples involve The Hershey Co. and Unilever. For its part, Hershey markets its Kit Kat chocolate bars as having a distinct snap sound that is discernible from the rest of the category.
Sound is an essential part of crunchiness, which also was made very clear when customers shunned Unilever’s Magnum ice cream bars after they had been reformulated. The goal was to prevent the chocolate coating from slipping off the ice cream bar.
However, Unilever discovered consumers actually relished this “problem,” and the slipping and breaking was an essential part of their eating experience, along with the iconic crackling sound produced by the brittleness of the chocolate coating. Subsequently, the focus shifted to preserving the sound intensity and texture of the ice cream bar coating.
The sound emitted by crisp and crunchy food is closely related to its textural attributes, so changes in process technology or in the recipe can have a direct influence on the rheological characteristics of the products—and on the quality and texture of the end-product.
Factors controlling the sound of crisp products can be categorized into three groups: processing conditions, ingredients (and particularly, hydration), and structure. Roasting can affect the acoustic properties of nuts, making them louder (and crunchier) than their raw counterparts. When a crunchy product is broken, crushed, or chewed, characteristic sounds are produced due to the brittle fracture of the cell walls. These sounds (acoustic emission) have been shown to be directly related to sensory crispness and crunchiness.
Most low-moisture, baked, or extruded products, such as breakfast cereals, wafers, biscuits, and snacks have a crispy texture as a function of water activity or water content. As the moisture content of these products increases due to water sorption from the atmosphere; from adjacent components inside the product; or from phases of production, the crunchiness and crispiness disappear.
Similarly, the crunchiness of fried or baked batters and coatings changes with water activity and moisture content. The acoustic behavior and the related crunchiness of starches is related to the glass transition temperature (Tg) of starches and is affected by water. Breadings and batters tend to become practically silent when their moisture content exceeds 10%, as a result of the transition from a glass and rigid structure to a rubber one.
Nuts and Grains and More
Grains and seeds create texture and culinary excitement, in addition to serving as the workhorse in batters and breadings, and increasingly are incorporated into inclusions.
Consumer interest in ancient and sprouted grains is an emerging trend, with the introduction of an impressive range of textures and nutritional benefits, along with distinctive flavor profiles. The selection of the grain and how they are processed can further expand the offering of textures, nutrition, and flavors.
Wheat flour is the traditional ingredient of choice for baking and coating applications, but rice, tapioca, potato, yam, banana, and other flours are moving into the mainstream as substitutions to cover the demand for gluten-free formulations. Rice flour-based batter is one of the more common, having both a long tradition via Japanese tempura, plus properties of economy and function.
Rice flour has better water-holding capacity and usually takes up less fat than a wheat flour-based batter system, for a healthier product with fewer calories. Sprouted brown rice offers additional nutritional benefits over its white rice counterpart, as a result of the sprouting-related release of nutrients.
Coarsely ground spelt and kamut, ancient cousins of wheat, provide the topical application with an uneven surface, which adds to visual appeal and enhances crunchiness. Sprouted grains, because of the conversion of complex carbohydrates to simple sugars, add sweet undertones that can be lost during high-heat frying, but are subtly pleasing in coated and baked products.
Nuts are perhaps the most popular inclusion to add texture, flavor, and health to foods. They also have a long history of popularity in coatings. This is, in part, due to nuts’ unique textural contributions and favor profiles—not to mention their added cache as gluten-free nutrition.
In addition to crunchier crushed nuts and peanuts (actually a legume), finely granulated nut flours (such as hazelnut or almond flour) mimic light breadcrumbs, like panko, in breaded chicken and vegetables. In batters for fried chicken and eggplant Parmesan, coarsely ground almond, unlike breadcrumbs, does not become soggy after sitting for a while and delivers a delightful crunch with every bite.
Healthier options in prepared foods will continue to be a trend. Ingredients used to add snap and crunch, both inside and outside, allow product makers the option of adding the same indulgent, rich characteristics once only associated with fat and sugar. The use of creative coatings and inclusions will allow manufacturers to let exciting textures sit in for those other organoleptic qualities.
Kantha Shelke, PhD, is a principal at Corvus Blue LLC, a Chicago-based food science and research firm specializing in industry competitive intelligence, expert witness services, and new product/ technology development and commercialization of foods and food ingredients for health and wellness. She may be reached at email@example.com.
Cheers for Beers
Beer is popular in many batter coatings, because beer-battered foods—fish being the most popular— stay juicy, and the beer helps the crust stay crisp and crunchy. Using real beer in the batter adds proteins, carbon dioxide, and alcohol, which act as foaming agents to help aerate the batter.
Aeration helps insulate the frying product against the heat of the frying medium, allowing the coating material to fry quickly into a crunchy texture, while protecting the delicate structure of the enclosed fish. But this type of batter also works perfectly well for tender vegetables, such as mushrooms, without toughening them or allowing the internal moisture to seep out and ruin the frying medium.
While chefs and home cooks can use a wide range of real beer in batter for aeration and juiciness, food manufacturers might choose to enhance the consumer experience with flavor extracts and concentrates that not only highlight the desired intensity of beer but also maintain consistency in year-long production.
These flavor enhancers are made from alcohol reductions prepared by controlled heating of the beer to evaporate the alcohol and water, yet retain the aromatic volatiles. For manufacturers and foodservice operators, reductions offer concentrated flavor profiles for cost-effectiveness and ease-of-use. Fried coatings with flavor additions have a special effect on the perception of crunchiness. Sweet, rich flavors tend to soften perceptions of hardness, while salty, savory flavors reinforce perceptions of hardness and crunchiness.