Manipulating Flavor Perception in Functional Products
by Heather Granato
Flavor perception is a complex interaction between taste, aroma and chemosensory input. The brain combines data about scent impacting olfactory nerves, molecules interacting with taste buds, and textures and temperatures changing mouthfeel. Consider the flavor difference between a tomato picked off the vine on a hot summer day and one pulled from the supermarket bin in January. Sensory interaction, stored memories and expectations, and new experiences synergistically affect flavor perception.
Increasingly, as consumers turn to their food for more than just the standard caloric nourishment, they're running into nutraceutical add-ins that change the flavor composition of a previously known item. A vanilla milkshake has an understood profile; however, a soy-based, vitamin-enhanced meal replacement "vanilla" shake might have the same visual correlation but a very different flavor perception. To enhance the flavor experience in functional foods and beverages, manufacturers are increasingly turning to flavor houses not just for masking agents to cover off notes, but enhancers and modifiers to change the texture, taste and aroma of the product itself.
Understanding Flavor Perception
When consumers think about "flavor," they often associate it most directly with "taste." The sense of taste picks up the basic sensations of sweet, sour, salty, bitter and umami (a savory or protein sensation). According to a presentation at the International Conference on Complex Systems in May 2000, these tastes help determine edibility. "Sweet foods are generally non-poisonous and provide needed calories; sour fruits generally have the vitamin C which we need to survive, but may also be sour because they are not yet ripe and ready to eat; we need to eat a certain amount of salt to remain healthy; umami is a signal for the presence of protein; and finally, toxic substances, such as many alkaloids, are generally bitter." (D.R. Bauer, et al, Cornell University)
Molecules bind to taste buds that transmit taste information to the brainstem, which in turn relays the input to the cortex. There, it is combined with information about the scent. Chemoreceptors in the olfactory nerves pick up aromatic compounds and relay the information directly to the cortex. Bauer noted that a portion of this input goes directly to the hippocampus, explaining why smells are strongly associated with memory. Finally, chemosensory perception picks up chemical irritants or other trigeminal effects, such as hot or tingly, and adds those to the mix.
Combining the sensations imparted by a food results in "flavor." What has posed a difficulty in the development of many functional food and beverage products is the inclusion of nutraceutical components that are odiferous, bitter or astringent. Past experiences with these scents and tastes make most consumers reluctant to consume products that have similar attributes, regardless of the possible health benefits.
Therefore, manufacturers have adopted methods of hiding the flavors in their products. Most start with masking agents to neutralize flavors in the functional base (for more on masking agents, see the Jan. 14 issue of INSIDER). From that point, formulators will develop an acceptable flavor profile using flavors, enhancers and modifiers to reach a palatable conclusion.
Enhancers and Modifiers
Generally, enhancers work on the aromatic and taste attributes of a product, while modifiers impact the chemosensory perception. The Food and Drug Administration's (FDA) Code of Federal Regulations (CFR) has a specific definition of flavor enhancers and modifiers, according to John Houtenville with Erlanger, Ky.-based Wild Flavors. "The definition of a flavor enhancer is substances that are added to supplement, enhance or modify the original taste and/or aroma of a food without imparting a characteristic taste or aroma of its own," he said. "However, from a functional standpoint, enhancers and flavors overlap. Consider mint, which imparts a characteristic flavor but also imparts cooling."
Enhancers can work on aromatic qualities without impacting taste. Olivier de Botton with OSF Flavors in Windsor, Conn., gave the example of a raspberry flavor in a product that is missing the aromatic sensation. "A raspberry enhancer can give a very specific floral note to augment the scent," he said.
Other flavorists suggested using acids to enhance a tropical or citrus note or using vanilla to round out sweetness. "A lot of taste in a product is not just taste but visual perception and aromatics," said Bob Marinicic with Blue Pacific Flavors in City of Industry, Calif. "Some nutraceuticals, such as B vitamins, have their own aroma, so you have to cover those aromatics as well."
Understanding the functional qualities of nutraceuticals, and which compounds are lending efficacy, can also assist in developing flavors. "As a formulator, you need to understand what type of compounds, such as ginsenosides in ginseng, are lending those bitter, alkaline notes," said Adib Nassar, chief executive officer with Livermore, Calif.-based Western Flavors & Fragrances (WFF). "If you use pure extract and play with flavors with those chemicals, you know directionally which way you want to go with the ultimate flavor."
Lawrence Buckholz, Ph.D., with J. Manheimer in Teterboro, N.J., agreed that understanding the functional portions of nutraceuticals is important to developing a full flavor profile. "A lot of the functional part of botanicals are based on glycosides and alkaloids, which are alkaline substances affixed to the sugar portions of plants, which are usually bitter and very hard to cover," he said. "You can cover them to a point where they're acceptable, but you can never cover them completely."
Instead, many chemists also work with modifiers to change the mouthfeel or oral perception of a product. "Modifiers, such as pectins, come in the finished application to get a lingering impact with the flavor," said Eardley Fernando, a flavor chemist with WFF. Some companies offer proprietary technologies that focus on modifying the trigeminal effects of nutraceutical ingredients in functional products. "These offer non-characterizing effects on the palate other than characterizing flavors, such as providing lubricity or creaminess and fullness," Buckholz said about J. Manheimer's Oral Perceptions® line.
Ultimately, flavor chemists work with aromatic, semi-aromatic and semi-volatile compounds to achieve proper flavor perception. "This is a blend of art and science," Houtenville said. "You need to know your chemistry and make stable flavors, using adjuncts to modify the basic taste characteristics and trigeminal perceptions."