Magnifying Flavor Through Layering

Sophisticated chefs build flavors one upon the other to give dishes variety and depth. In food processing, designers can apply this same technique to enhance a flavor profile, thereby adding distinction to the product and enriching the eating experience.

Consider this concept in sauces and stocks. Ever wonder how authentic Mexican mole sauce gets that deep, rich flavor? Or why one chef’s stock is appreciably more complex?

In each case, flavor layering makes all the difference. Trained chefs may layer flavors intuitively, or automatically. They know it’s all about balancing flavors by adding complementary ingredients at different stages of a recipe, and taking every opportunity to bring out the unique qualities and contributions of each ingredient.

Why is flavor layering such a hot catchphrase—and concept—in culinary circles? Some of the reasons include the fact that the world is quickly shrinking in a metaphorical sense, while, as a result, our palates are rapidly expanding. More people are traveling to more places around the world, for work and for pleasure. And on those travels, they’re sampling more street food and exotic delicacies. Widespread immigration is contributing to the expanding American palate as well, with immigrants introducing time-tested recipes and flavors from the Old World, as well as numerous Latin American and Asian locales—just to cite a handful of different peoples that have been continually diversifying the American cultural landscape. And, of course, new ingredients continually surface, and creative chefs always look for new ways to combine ingredients.

Let’s look at that mole sauce again. In particularly successful mole sauces, toasted chiles, ground spices, roasted nuts, charred onions and tomatoes, and soaked, dried fruits are artfully combined to create a sauce in which multiple layers of flavor are perfectly melded, without any one taste predominating.

Or take a distinctive ingredient like habanero peppers. To bring out subtleties that are masked by its heat, a chef might add a citrus or smoke component to coax less prominent flavors to the forefront.

Taste goes beyond buds 

The best chefs always remember that all senses are engaged in tasting, not just the taste buds and nerves on the tongue and elsewhere in the mouth. We’re all familiar with the role of smell in tasting. Most often, the aroma is intrinsic to the dish. Just think of the delicious smell of roasting chicken. It makes your mouth water.

Now look at the way some of today’s trend-setting chefs are using aroma as a “seasoning.” Homaro Cantu at Chicago’s Moto restaurant heats aromas in a box or incorporates them into silverware to influence the diner’s perception of a dish before it’s tasted. Restaurateur and culinologist David Burke has created a line of sweet and savory flavor sprays to create the illusion of flavor in low-fat products, relying at least in part on the ability of aroma to influence taste.

Crispy, crunchy, smooth, juicy— the texture of a food contributes to the flavor of a food—it coats the tongue, creates bursts of flavor on the palate, or releases flavors quickly or slowly, building a layered effect as the mouth perceives flavors in different ways over a period of time. Temperature also affects the perception of flavor in exciting ways. Put a spoonful of chocolate ice cream spiked with chipotle chiles in your mouth. First you’ll sense cold, then sweetness. As the ice cream warms in the heat of your mouth, the smoky quality of the chiles comes forward. And then, finally, you experience the heat.

Complementary contrasts 

A complementary contrast is not an oxymoron in a chef’s world. And in the world of flavor layering, complementarity and contrast are key principles. They enable the chef to blend aromas, tastes and textures while keeping individual qualities distinct. A familiar dish like mashed potatoes is enlivened with chipotle purée, then rounded out with a cilantro-flavored oil that creates richness in the mouth, fresh herbal aroma in the nose and another layer of flavor on top of the neutral flavor of the potatoes and the spice of the chipotle. And who has not enjoyed the unfolding of tastes and textures that excite the palate when we eat sushi—the vinegared rice as the base, topped with the brininess of raw fish, the bite of wasabi and the grounding umami of the soy sauce.

Flavors unfold over time and, interestingly, flavors added last often hit the senses first. A rich braise can be garnished with freshly cooked vegetables and enlivened with a splash of vinegar at the end of the cooking process. Then it gains another layer of flavor from a sprinkling of chopped raw herbs to echo the bouquet garni that was added at the beginning of the cooking process. Diners enjoy the aroma of the fresh herbs, then the brightness of the vinegar and the crunch of the vegetables. They only gradually perceive the deep, rich flavor of the slow-cooked meat and vegetables, and the bottom notes of the original seasoning. Thus, the layers of flavor reveal themselves in reverse order.

Many roads to flavor layering 

Thanks to modern food technology, ingredients are available in many interesting and varied forms, from powders and oils to individually quick-frozen (IQF) and freeze-dried types. Each form has its own distinctive texture, flavor concentration and application possibilities.

Sometimes, incorporating more than one form of an ingredient into a dish or manufactured product helps create layered complexity. A Spanish romesco sauce contains roasted fresh peppers that retain their vegetal quality but contribute intriguing roasted flavors, as well. Add to that the concentrated, smoky quality of spicy paprika, with its sweet and hot notes, and the sauce really starts to sing.

In a more-contemporary example, a chef might add the concentrated aromatics of orange oil to a dessert to enhance the brighter, more-acid quality of the fruit’s flesh, or a few drops of banana extract to a banana pudding to make the flavors “pop.” Similarly, tomato powder enhances canned tomatoes, just as a bit of tomato paste lends sweetness and depth of flavor to a sauce made with fresh tomatoes that lack the desired intensity.

Using different forms of the same ingredient or flavor translates well when designing processed foods. A hot paprika may contribute a strong flavor note, a smoked paprika can add depth, and an oleoresin at the end helps shape the desired color. Oleoresins can also counter the tendency of flavors—like herb notes and alcohol flavors—to flash off in the production process. Adding more-volatile flavors later in the production process also helps prevent flavor loss. When designing processed foods, it also typically makes sense to add more of a given flavor than would be used in a foodservice setting. Another way around these concerns is the use of encapsulated flavors, though this is not always practical in terms of expense.

Many classic culinary techniques use the principle of flavor layering. Roasting bones, sweating vegetables, reducing wine, adding stock and slow-simmering ... this is the time-tested sequence that leads to a well-rounded stock. Each step in the process contributes its own layer of flavor. Contrast that with the insipid brew that would result if all the ingredients were simply combined in a pot and boiled.

In the food-production facility, culinary bases are useful for replicating nuanced layers of flavor. A roast-chicken base for roasted notes, a chicken-fat base for mouthfeel, and a marrow-flavor base for subtle flavor notes can recreate a classic stock without the traditional input of time and expense. And again, using different forms of the same vegetable creates further complexity—for example, a raw-carrot flavor for sweetness and a roasted-carrot flavor for depth.

Braising creates depth and richness by many of the same means. Osso buco, the classic Italian dish of slow-cooked veal shanks, adds another layer of complexity at the point of serving with a scattering of gremolata (chopped fresh parsley, garlic and lemon zest) on top. The brightness of this mixture acts as a counterpoint to enliven and revive the wintry flavors of the braised veal. To add complexity to a braised dish, chefs often marinate the main protein in wine or vinegar with herbs and spices, then brown it to add the rich flavor compounds of the Maillard reaction before the slow-cooking adds yet another layer of flavor from cooking liquid.

The layered flavors that develop during the long, slow cooking of a classic braise can be reproduced in the production facility by tumble or vacuum marinating the veal shanks to facilitate penetration of flavors down to the bone, and by braising under pressure to minimize any flavor loss in spite of quicker cooking time. Wine that has been reduced separately should be added later in the braising process, to avoid flash-off and to retain the desired flavor notes. Roasted flavor bases contribute another layer of depth when initial browning of protein is not feasible. Finally, the rich mouthfeel created by the extraction of gelatin from bones during braising can be reproduced with modified food starch, and caramel coloring contributes eye appeal. Add a packet of freeze-dried herbs and lemon zest—to be reconstituted by the end user—to reproduce the final flavor “pop” of the sprinkled gremolata at the end. (For more hints and tips on how to translate classic braising techniques from the kitchen to a manufacturing environment, see “Braising for Maximum Flavor” in the June 2006 issue of Food Product Design.) 

Dry and wet rubs work in a similar fashion to impart layers of flavor to foods destined for grilling or smoking, or for roasting in a wood-fired oven or tandoori. By the time a plain old steak lands on the platter, it can have several strata of seasoning: from a spice rub, through the browning of the grill and the smoke of the fire, a final seasoning with salt and pepper, and the flavor burst of an accompanying condiment or compound butter (butter creamed with herbs, garlic or another flavorful ingredient). Tumble marination can increase flavor penetration in a food-production setting, combined with a judicious selection from the wide range of flavor bases available—from roasted to spicy to smoked.

Sous vide (cooking in a vacuum pouch at low temperatures), is an increasingly popular way to layer and intensify the flavors of food by capturing their natural aromas, or by increasing the penetration of added seasonings. In a related technique, the classic fillet of sole en papillote, that is, wrapped in parchment paper with aromatic herbs and a splash of wine, seals in flavors and provides the temporal “layering” of a burst of aroma to entice the palate when the parchment is cut open by the diner.

At the present time, sous vide is not as widely used for retail food products as the cook-chill process, which involves cooking foods at higher temperatures and then quickly cooling them. The reasons for the hesitancy to use sous vide for retail products —and generally on a wider basis—stem mainly from food-safety considerations from governmental officials and the need for more-precise, set parameters (like very specific water temperatures and cook times) for specific applications.

However, the advantages that sous vide cooking supplies in terms of flavor penetration, tenderness and retaining the integrity of delicate foods like fruits will doubtlessly lead to further exploration of this technique.

Infusion also adds new layers of flavor to foods. A hint of star anise unfolding its flavor in a Chinese broth, citrus zest steeping in hot milk for a custard, basil steeping in olive oil—each of these preparations takes advantage of the infusion principle to extract flavors that can then become the top or bottom layer of yet another culinary preparation. Fresh fennel added to the broth will echo and intensify the anise; candied peel garnishing the custard pulls out the subtle flavor imparted to it by the oils in the zest; basil-infused oil, drizzled over a salad of fresh tomatoes and mozzarella, rounds out the acidity with the grassy flavor and aroma of the herb.

In the world of processed foods, to reproduce the delicate flavors of ingredients like herbs that might dissipate quickly after infusion, essential oils, oleoresins or encapsulated flavors are practical substitutes—and also help retain the aromas so vital to flavor perception. Vacuum packaging, which pulls out air and adds nitrogen, could potentially help add the element of smell to the layering mix, by incorporating the aromas into the nitrogen to be released when the package is opened. Microencapsulated aromas, which ingredient manufacturers can program to “pop” at a certain temperature, are another avenue for exploration.

Presentation can reinforce the concept of layering in a visual way. Think of the stacked platings—a way to control the order in which flavors hit the palate—that were all the rage a few years ago. It’s also wise to remember that one food doesn’t have to carry all the flavors. In fact, overloading the center-of-the-plate component with incompatible seasonings can fatigue a diner’s palate.

Instead of adding too many different things to the main protein, let the sides do a little work. Keep the flavors clean by adding one herb or spice to the starch and another to the vegetable to complement the predominant flavor palette carried by the meat or fish.

This concept can come into play somewhat in a frozen entrée, where the flavors of the heat-and-eat product complement each other rather than simply standing on their own. Sauce pellets that melt into vegetables upon heating can prevent the flavor of the vegetables from leaching out into other components of the dish.

Although many classic flavor combinations find wide use in foodservice kitchens and prepared food products, sensory testing continually adds more unique ingredient combinations to the product designer’s toolbox.

From the kitchen to production 

Chefs and technology have been in the news lately. Molecular gastronomy is hot, as adventurous culinarians play with high-tech equipment and forms of food not commonly seen in restaurant kitchens. Vapor-filled boxes, edible menus and unexpected temperatures and tastes are loved or hated by the critics—but never greeted with indifference. Some of these fads may be short-lived, but some may become significant trends that help form new approaches to flavor layering. Chefs and culinologists can play an important role in product development, by thinking creatively and upping the ante for product developers who find themselves entrenched in standard ways of thinking about and using technology.

The chef’s emphasis on the visual aspect of presentation and on the impact of aroma on flavor opens many avenues of exploration for food-product developers looking to incorporate the concept of flavor layering into foods. Packaging—which can advertise the attractiveness and the literal layering of the foods inside the container, be it glass or plastic—also plays a role in creating the visual “sell” of the layering concept.

Packaging condiments and sauces separately from the main ingredients —in pouches or miniature squeeze bottles that the diner can control —reinforces the idea of flavor layering while preserving freshness. For example, a salmon fillet could be packaged with a miniature squeeze bottle of reduced balsamic vinegar and a packet of freeze-dried lemon zest to create a layered flavor profile.

Letting consumers do some of the “work” makes it easier to retain subtle flavors and, in the process, gives them the ability to personalize the final dish. It also plays into the desire for the consumer to be part of the “speed-scratch” meal-creation process while minimizing the potential for consumer confusion or error. This approach appeals to consumers who are becoming savvier than ever about flavor, having experienced the excitement of ethnic seasonings and the depth and subtlety of flavor layering in high-end foodservice. The bottom line is that creative packaging can widen the possibilities for product designers, making it easier to retain nuances of flavor layering that are now lost in volume production.

Choosing the right food ingredients can assist flavor layering in large-scale production. For example, scoopable and other frozen purées are a simple way to create a bottom layer of authentic flavor and seasoning, whether the flavor profile is Asian, Latin American or Mediterranean. Some purées retain ingredient particles with the visual and flavor integrity that contribute a vital element to layering.

A Latin American spiced purée blend might make a good starting point for a ceviche base to mix with scallops. The base can contribute “ready to go” flavor layers, while lime juice provides acidity and bright flavor for a final top note.

Single-ingredient purées such as garlic, ginger and onion provide the consistency that is vital to the formulation of layered flavors and the versatility to combine well with other ingredients in marinades, coatings and sauces. Controlled-moisture, fire-roasted grilled vegetables, whether bell peppers, onions, chiles or blends, are also a great tool, because the layered flavors are built right in: the essential quality of the vegetable itself (which is not lost in thawing compared to regular IQF) and the smoky, caramelized overlay of the fire-roasting process. In large-scale production, controlled-moisture vegetables work well as topicals for breads and pizzas, because they won’t water down flavor or make doughs soggy. In bread production, they won’t compromise formulations or change the color of the product.

Chefs are at the forefront of the increasing emphasis on flavor layering as a prime consideration in designing recipes. Though the principles are not new, flavors from the global pantry, advanced technology adoption and increased focus on the visual and aromatic aspects of gustatory perception have taken explorations to exciting new frontiers. As chefs push the edges of the flavor envelope, they can inspire and guide food-product developers to create products that satisfy the demands of an ever-more-perceptive consumer palate. 

Matthew Burton is director of culinary innovation at ConAgra Foods, Omaha, NE. He is a Certified Research Chef and a member of the Research Chefs Association.