Whether it’s crunchy or chewy, consumers are more tuned in than ever to textural variation in foods. A report by consumer research group Mintel Ltd. revealed that product launches making a specific texture claim nearly doubled from 2011 to 2015.

“Texture can be more important than flavor when determining overall liking,” says Matthew McSweeney, PhD, assistant sensory professor and director of the Centre for the Sensory Research of Food at Acadia University, Nova Scotia. “Flavor is a more polarizing sensory attribute, and preferences can range greatly, but one would be hard-pressed to find a person who prefers a mushy apple to a crisp one.”

Researchers have discovered that the enjoyment of the eating experience is more enhanced by texture than previously recognized. In fact, it’s now known that the enjoyment factor is actually influenced by the sounds that come from the food we bite into.

“Auditory input is highly important when eating,” says Lisa Duizer, PhD, professor of sensory science at the University of Guelph, Canada. “Sensory experts categorize this input into ‘crispy,’ ‘crunchy,’ and ‘crackly’ sensations. You can have ‘wet crisp’ (similar to an apple) or ‘dry crisp’ (like a cracker) extrusions or inclusions.”

The crisp perception of a fresh apple or pepper comes from moisture released from the cell walls rupturing during the bite. A similar phenomenon occurs in dry crisp products, such as extruded products like cheese puffs, where cell walls are large enough to be visible. The walls vibrate when breaking, causing the characteristic snap during biting. (Duizer notes that, although there are specific differences in the sensations produced by biting “crisp” versus “crunchy” products, consumers typically use the terms interchangeably.)

Snack Attack

The snack category is experiencing exponential growth. Technomic reports that more than half of consumers surveyed say they eat snacks at least twice a day. The most popular—and quintessentially loud—snack foods are chips. They provide consumers with the classically beguiling combination of crispy and crunchy.

With consumers choosing healthier options, the preparation method of chips has evolved from frying to include baking, extrusion, gun-puffing, and combinations of heat and pressure (think popcorn or rice cakes). These have allowed for myriad new snack offerings, all touting crispness and crunch as primary indicators of quality and freshness.

However, as consumer preferences become increasingly more demanding, formulators must work with a greater variety of ingredients, predominantly starches. In conducting extrusion tests, McSweeney learned that panelists consistently preferred a less dense product that they described as “crispier with a better crunch.” This can present certain hurdles for product developers.

“The challenge with extruding less common ingredients like millet and other ancient grains was finding the ‘sweet spot’ of consumer acceptability,” says McSweeney. “That’s where the product delivered the textural expectation for crunchiness, while maintaining a light, airy texture, such as with a more common corn-based extruded snack. We had to tinker with the product moisture content as well as the extrusion conditions, including pressure and aperture of the extrusion die, to optimize expansion. A larger, fluffier product with more air pockets provided a better auditory crunch, and thus increased consumer preference.”

Baking and frying both reduce moisture in a product, but in scale-up, frying can be messy.  Using a combination of convection and conduction in baking yields a low-calorie and lower waste product when compared with conventional frying. Switching can be a win-win for manufacturers who want to stay on trend while watching their bottom line.

One Step Beyond

“We have products in our Doritos line that we call a tooth-rattling crunch,” says Ngoc Trinh, R&D chef for PepsiCo/FritoLay’s Global Snack Foods division, commenting on the trends in development and innovation she sees in the snack food category. She says that the R&D team stays ahead of the curve by working with vendors to “really get it down to where we can find the line between crispy and crunchy.”

Trinh describes how the chefs developed the idea they call “crinchy” to describe that hybrid line. “We try to position our products within the ‘white space’ of crunch, especially within the shelf-stable crunchy category versus frozen...to create a great experience for the consumer.”

Sound Bite Science

Ingredient makers are well aware of the auditory aspects of enjoyment of a crispy or crunchy snack. They have developed starches to create nuanced levels and volume of sound. With such capabilities, chip and cracker developers can incorporate an auditory component for crisp or crunch, enhancing the perception of texture and thus the product itself.

Some of the trends Trinh is addressing include how to develop a unique crunch using whole foods and different plant ingredients, such as nuts and seeds. “How do these ingredients give a specific type of crunch, unlike the crunch from starches?” she posits. “We can use pre-gelled starch in a baked application, but how could we create a comparable crunch in a non-baked product?”

 Consumers gravitate to such texture combinations for a number of reasons. They might turn to a particular snack to engage in a crunchy mid-day munch-fest to “wake themselves up.”  Or they might choose a crisp snack as an indulgent little escape. “We focus on these types of stimulating eating experiences we understand the consumer enjoys,” explains Trinh.

Another snacking aspect Frito-Lay’s Trinh takes into consideration is how products are shared and enjoyed with family or friends. “Popcorn is the kind of product that calls for sharing with everyone,” she says. “We refer to this as the ‘Everyman’s’ crisp. On the flip side, that same product can completely change [in] a separate moment and the consumer will have a unique perception and enjoyment of the eating experience. For example, take that product out onto the field after a soccer game, where you want your snack to deliver satiation and a powerful taste and texture, to join that moment of excitement and playfulness.”

Trinh and her team are constantly researching ingredients to help deliver such experiences, “with a little bit of a unique twist” within their snack portfolio. Describing the evolution of the snack food category, she points out emerging trends such as snacks incorporating peas and carrots (“something previously unheard of in shelf-stable snack foods,” she exclaims) and repurposing vegetable scraps into veggie chips.

“Extruded snacks are moving away from corn and wheat and toward vegetable bases. I’ve seen skins of dehydrated vegetables and plants used to provide a unique type of crunch,” she adds.

“The scientists we work with have to understand how starches play with salivary amylase during chewing in one person as opposed to another, and understand glycolysis from a culinary standpoint. If you’re cooking corn and processing it in a certain way, it creates a totally different crunch depending on how you denature proteins and gelatinize starches,” Trinh explains. “We break these processes down to the micro level and daily are working to unlock them.”

Outside In

At the intersection of product development and culinary creation are innovators such as Ryan “Chef Ko” Cunningham of RollinGreens LLC Millet Tots. Ko put a number of clever spins on the classic tater tot. First, of course, was making them out of millet. Then, he took it to a deeper level, beginning his process at the farm.

“Sourcing sustainable, clean, organic ingredients starts with knowing the farmers. Building direct relationships with them brings good energy into our food,” says Ko. “We believe this, too, is a key ingredient.”

Using millet for the company’s first product was not intentional. Ko and Lindsey, his wife and business partner, say, “We didn’t choose millet; millet chose us. This semi-arid seed crop uses a fraction of the water other crops need, giving millet a leg up already before it even hits the kettle to cook.”

The commercialization process led sto some challenges for the team. “Scaling up from test kitchen to plant is never an easy process. Our millet tot’s crunch comes from multiple techniques, [including] timing, how we cook the grain, the way we form the tots, and using a state-of-the-art conveyer fryer to just crisp the outside. This makes our product low in fat and it doesn’t hold on to excess oil that would make the product soggy. The tots are then immediately frozen, which holds their crisp. This makes for the perfect tot.”

Scott Jensen, CEO and co-founder of Rhythm Superfoods LLC, follows trend data closely to develop new and popular snacks ahead of the curve. He predicts that the “better for you” snack category will only continue to grow. “Vacant carbohydrates, [plain] pretzels, and naked potato chips are static or declining in popularity, whereas snacks with better-for-you claims, such as higher vitamin and fiber levels, are growing at three to ten times the general snack category rate.”

Peeled Snacks Inc. (established as a B corporation) makes several types of organic, non-GMO dried fruit snacks and extruded vegetable snacks, including its popular pea and pea protein line, Peas Please. With 5g protein and a half cup of veggies per serving, the products use a proprietary combination of whole pea flour and brown rice flour to get the perfect light textural crunch.

Dry Ideas

Heat or low pressure can be employed to remove the free water from an item in order to change its sensorial properties. Popular examples include freeze-dried berries, dried apricots and other fruit snacks, and more recently, apple chips and kale chips. Food dehydration reduces the moisture content from well over 90% down to 2-5%, extending the shelf life to more than one year.

A challenge to the drying technique can be the accompanying browning reactions in fruits and vegetables. These typically are caused by enzymatic oxidation of polyphenols and other volatile compounds. These enzymes can be deactivated with the use of high temperatures during a pasteurization step.

Without a pasteurization step prior to drying, the drying temperatures alone are insufficient to inactivate these enzymes, due to the water evaporation cooling effect. That can lead to unfavorable browning of the product. The Maillard reaction also can cause browning with high temperatures.

Drying machinery designed to dehydrate rapidly to the 15-20% moisture range will decrease the time the product spends under conditions conducive to Maillard reactions, thereby minimizing the potential for browning.

Freeze-drying, while more expensive than conventional dehydration, is ideal for more delicate products and can help to preserve volatile aromatics that would be lost at higher temperatures. Freeze-drying functions by the scientific property of sublimation, when water turns to gas. This is achieved by freezing the fruit or vegetable, and submitting it to an environment of low vapor pressure, whereupon the frozen water will be removed from the product, leaving behind a dehydrated, crisp result.

Improved freeze-drying has led to a boom in recent years of such crisped snacks, especially from produce. These freeze-dried products are sold as-is or as an ingredient for a yogurt or dessert topping, breakfast cereal inclusion, etc. This method of dehydration helps to preserve the shape of the product, as the item will not lose its form, shrink, or distort throughout the process.

In freeze-drying, water evaporates from ice, without the ice melting, thus maintaining the structure, texture, and flavor of the original product. Rhythm Superfoods used the technology to expand on the highly popular kale chip. Early heat-dried forms of the trendy snack had a problem with short shelflife due to loss of structure. Freeze-drying gave Rhythm’s products improved structural characteristics. Rhythm recently added beet chips and broccoli clusters to its line of crunchy snacks.

Scott Jensen has been dehydrating veggies for retail since 2010. Recognizing a trend in natural and organic snack foods, Jensen co-founded Rhythm to bring a larger variety of batch-made, healthy alternatives to the snack aisle.

Dehydration technology has advanced over the years, with enclosed spaces and forced air now used to expedite the drying process, and manage the moisture levels.

A number of procedures and challenges specifically greet vegetable dehydration. “Some vegetables must be blanched in advance to improve the ease with which the product is dehydrated,” explains Jensen. “Without blanching, the final product can become hard, jumping past the ‘sweet spot’ of crunchy. To add flavor to our kale chips, we add a wet dressing to the fresh vegetables, and this sauce dehydrates simultaneously with the vegetable portion.”

Jensen’s team also adds ground sunflower seeds or cashews “to help provide a stickiness to the sauce, and add protein and fiber.” The other seasonings—lemon juice, vinegar, and spices—are then added. “Our developers know that, as opposed to dry seasonings that already give off the final flavor,” he elaborates. “The wet marinades we apply must taste like our desired flavor only after dehydration.”

To apply the wet flavor system, Rhythm’s chefs tumble it with the kale, hand-spread the product onto trays, then transfer product to the dehydrator. “Our QA team runs the moisture analysis to make sure the final product is crunchy. At the end of the dehydration process, you have dehydrated down to 2-3% moisture, and you now have a shelf-stable, crunchy product,” explains Jensen.

Rhythm also produces a line of roasted kale chips made in a rotary convection oven. “The roasting is much more sensitive, and there is a limited time in which the product is perfected; any earlier and the product is not cooked, and any later and the kale chip is burnt or overcooked,” Jensen says.

Sour With Snap

Alluring snap and crunch aren’t limited to chips, crackers, and extrusions. There are some functional ingredients that can bring the crunch factor to prepared whole vegetable applications, like pickles. Calcium chloride in the brine solution enhances the characteristic crisp factor, and helps maintain it throughout processing and handling. This interaction can be extrapolated to any product where pectin and pectinesterase enzymes are found as it counters the softening, improving strength and firmness in the pickled item

 Once Rhythm’s products are taken out of the dehydrator, they are transferred immediately to a moisture-controlled environment, since vegetables are hygroscopic and act like a sponge. They’re packaged with a desiccant pouch and with nitrogen flushing to ensure the desired texture remains until the consumer opens the bag. This also helps prevent oxidation and rancidity of the product.

Rhythm’s Roasted Kale Chips have a light mist of high-oleic sunflower oil, and many of the company’s other products are initially coated with sunflower or cashew oil to help flavorings adhere. In packaging of these items, too, nitrogen flushing helps to extend the life of both the product and its flavor.

Grains with Snap

More healthy options to satisfy the need for crunch are emerging in the cereal aisle. Many dairy companies are retailing single-serve yogurts with accompanying granola portions, for example, as a value-added textural proposition.

Kayla Tan, R&D and innovation scientist for organic breakfast and snack food company Nature’s Path, discusses the challenges that come with this. “The crunch factor is an important consideration in our development, as often consumers are mixing their granola or cereal in with milk or products that will impart moisture,” she explains.
“Moreover, our products are enjoyed as a dry snack, too. The challenge is to deliver the right amount of crunch for both scenarios.”

The base ingredients are key in determining what kind of texture the product will have, with corn and rice on the airier side and wheat providing a denser crunch. “Starch gelatinization plays an important role in results of corn- and wheat-based cereals,” Tan explains. “We experiment with different levels of gelatinization to find the perfect combination of airy crunch and the harder bite crunch.”

Cooking methods also play a key role in maintaining the texture of Nature Path’s cereal-based products. The company relies predominantly on baking to achieve its goals. “The trick is to manage moisture content, which can be accomplished by coating the products to create a barrier that prevents moisture migration, or through the use of functional ingredients like starches,” Tan says. “We are also careful about packaging, especially since we don’t use preservatives to maintain crunch. Therefore, innovations such as high-barrier packaging and much more can go a long way to complement the R&D process.”

The Crunch Inside

For some consumers, crunch is best enhanced by the surprise effect. Crunchy or crispy inclusions hidden throughout a product, or in the center of a product with a different texture surrounding it, only add to the enjoyment of a product. Nuts historically have been among the most favored providers of that characteristic.

While nuts remain a popular whole-food inclusion to provide a crunchy texture, development with nut analogs has become increasingly popular. This is driven largely by the “allergen-free” trend. Often based on stabilized wheat germ, nut analogs can give the appearance, flavor, and texture of a nut, without the cost, crop volatility, or allergens.

With the desire for healthy products, the popularity of other crunchy bits, from toasted seeds, grains, and even legumes (such as soybeans or peas) to superfoods like crispy dried berries and cocoa nibs, has taken a greater foothold.

Innovation with these ingredients is present in nearly every aisle of the grocery store, as more developers turn to nut alternatives to avoid allergens. Of these alternatives, toasted peas, beans, and other pulses are perhaps the most popular. They are extremely versatile, and can assist in development in many forms. Whole pulses add a crunch as an inclusion, such as toasted yellow peas or soybeans substituting for nuts.

What’s good on the inside is good on the outside, too, as crunchy coatings also are increasing in popularity. The processed forms of pulses and whole, gluten-free grains are finding more uses as flours and proteins in breading.

Pulses, including lentils, chickpeas, beans, and peas, are high in protein and fiber, and come with the added marketing benefit of being gluten-free. When used as a replacement in breadings, pulses have been found to be as functional as wheat- and corn-based ingredients, while attaining a fiber content claim.

Wrapped in Texture

For conventional fried and baked proteins, it’s all about the batter and breading systems. These two systems alone or in tandem really boost the texture, especially the crunch factor. By battering and breading a soft protein, and then cooking it in fat, you end up with product that has the crunchy exterior and juicy interior that is universally enjoyed.

Ancient grains—such as flax, millet, amaranth, and quinoa—are riding the wave of going back to tradition as well as aiding consumers in finding non-meat sources of proteins, healthy fats, and minerals. These grains are being incorporated into breaded chicken tenders and breads, and are used as breading substitutes or value-added components.

“The ancient grains provide a definite boost in color and texture and interesting visual characteristics,” says Daryl Simms, product development manager for Pinty’s Delicious Foods Inc. The difficulty found in working with those ingredients, however, is the flavor. “Flax seed often imparts an undesirable flavor,” he warns. “The balance between functionality and flavor of these ingredients will become better understood as these ingredients move further into the spotlight.”

The breading or dusting applied to fried or baked foods can vary significantly depending on the application. It is important to consider factors such as the type of flour and its composition, the inclusions of other starches, and the cooking time, temperature, and method—all of which have an impact on the crunch of the product.

Flour Power

Although breaded and fried or baked products typically enjoy more textural leeway among consumers, a crispy and crunchy texture is a highly desirable characteristic in fried chicken. When striving to create the perfect piece of fried chicken, chef and baker Alfred Castro can’t stress the composition of the flour enough. “You must have a perfect balance of protein and ash content in the flour to give you the best bite possible,” he says. “Using too much hard wheat, or higher protein content flour (10-13%), will result in fried chicken that can be too hard, like biting into a brick.”

Castro explains that too much protein in the breading can result in an excess amount of oil being absorbed. Too much soft wheat flour, with a lower protein content (8-10%), will produce a breading that lacks a good, crunchy texture, and tends to be more soft, brittle, and fragile.

Other considerations include the protein (chicken, in this case) being fried, such as shape, thickness, and whether it’s bone-in or not. And then there’s the final application: whether it’s for immediate consumption, foodservice (thus needing a long hold time), or if it will be partially or fully cooked for freezing and reheating.

“You can find flour that is naturally perfect for fried products, but the cost can be high and the supply limited,” says Castro. “It generally requires a blend of hard and soft wheat flours to generate the ideal balance, and a texture that is nice and crunchy with the right amount of ‘shatter,’ all at the right price.”

Castro constantly tests flour composition as it changes with seasons and suppliers, often changing the mixture of hard and soft wheat flour to maintain that perfect balance. “It also is important to pay close attention to the ash [mineral] content of flours because ash affects the texture too,” he explains. For an ideal crunch, that is not too hard, he suggests that ash content be less than 0.5%. A relatively high ash level can make the bite too hard and cause excess oil absorption.

Pinty’s Simms agrees. The company provides a variety of pre-made chicken products designed to be fried, baked, and microwaved from different stages of preparation. With varying cooking methods being used for different products, Simms and his team use a number of breadings and batters to achieve their desired texture. Both Simms and Castro note that they use a variety of starches for breading and batters.

Castro also suggests the inclusion of Japanese-style bread crumbs (panko) to a breading to add a level of texture and boost the crunch factor. An approach for pushing the breaded texture envelope that Simms endorses is additions such as tortilla chips, potato chips, ramen noodles, and even that old standby, corn flakes.

Starch Work

The addition of starches from sources such as rice, corn, potatoes, and tapioca allows processors to craft a specialized crunch or crisp for a product. For example, adding rice starch or flour can create a light and crisp texture in a batter, as in tempura batter.

Potato starch can be added to increase crispness as well. Simms warns, though, that potato starch can cook up pale in color. However, it can be added in small amounts to wheat flour to create a softer yet crisper texture.

The perfect piece of fried chicken isn’t just about the breading. The batter plays a major part in delivering crunch to chicken and other fried foods. “Batter is just as important as breading,” says Castro. “It gives you the layers of texture and flavor that take fried item to the next level.”

Certain starches included in the formulation can help with breading adhesion, as well as with creating a shell that protects the crunchy breading and allows the coated portion to steam within the batter shell. “The addition of certain starches in a pre-dust or in the batter can help prevent moisture migration from the core to the breading,” says Simms. Without this step, the breading can become a soggy, gummy mess.

The addition of modified starches also helps significantly with freeze-thaw stability. Simms uses baking soda and other leavening agents give improved texture to breading.

Although consumers have an abiding affection for fried foods, healthy alternatives continue to attract. The catch is that, to be successful, they must mimic the organoleptic characteristics of fried foods flawlessly.

Crisp texturizing starches also can help processors make the transition from fried products to baked products. Functional starches add back some of the desirable texture lost during baking, as opposed to frying. The functionality desired can be created by choosing different starch sources, such as corn, tapioca, or rice.

Ingredient makers have developed cutting-edge starch production technology methods that allow them to customize textures with unprecedented accuracy. Depending on the product desired, different starches are beneficial to the formulation as they improve expansion, sheetability, and texture.

High-amylose starches are one example. They contribute a hard, crunchy texture to breading, when compared to high-amylopectin or waxy starches. Results depend on the technology applied to the processing of the starch (such as type of modification and type of starch used).

Some starches can also significantly reduce the amount of breakage in a chip, and improve sheeting of the product. Tapioca starches in particular can add a hard, crunchy texture. One aspect of these starches is that they bind moisture during mixing, and will rapidly release moisture during baking, to assist with the crispy or crunchy texture. Working with functional starches can bring more control to items such as crackers. Developers can make a crisp texture that is soft and snapping, or hard and shattering.

Mouthfeel Transference

Compared to baked chips, fried chips start out firm but have a significant oily perception, with lower duration of pastiness. They also are accompanied by a residual mouth-coating and oiliness.

This typically is not the case with baked products. Baked chips are crisp at the beginning, but have a longer duration of pastiness and tooth-packing, followed by a mouth-drying sensation at the end.

With these new starches, the residual mouth-coating and oiliness can be imparted to better mimic a fried product. The starches can also bring back that initial hard bite and firmness to improve the experience for the consumer.

Feel the Pulse

Use of flour and protein concentrates derived from pulses continues to rise, due to their perceived health and wellness-related properties. These include their being high in protein, fiber, minerals, and micronutrients, as well as naturally gluten free. In addition, most pulses leave a lower carbon footprint compared to other grain and protein sources.

Pulses also have an excellent ability to provide expansion in a puffed product, while contributing minimal flavor. Fava bean flour can provide some protein and structure to create an airy, crispy extrusion, with minimal tooth-packing. And pea and lentil flours contribute a light, crispy texture in a batter, with good color and even coating around the core.

“In snacks, we try to develop flavors in layers, in addition to developing textures in layers and over time,” says Trinh. Developers and research chefs can follow suit as “textural differentiators” to continue to promote development and marketing across the food industry.

Kirsten Benneter, Liz Chan, and John Shackelford, MSc, head up the R&D, Processes Improvement, and Culinary factions at private-label custom manufacturer Giraffe Foods Inc. Their shared love of cuisine and innovation helps propel Giraffe to new heights, with food safety and customer satisfaction being their top priority. The authors are graduates, respectively, of McGill University, University of Guelph, and Louisiana State University. They can be contacted at www.giraffefoods.com or 905-678-2783.

Originally appeared in the July, 2017 issue of Prepared Foods as Things That Go Crunch in the Night.