There are many ways to go about creating flavors. Some approaches require a heavy reliance on scientific methods such as Gas Chromatography. Other approaches rely on a very creative approach which takes a target and breaks into individual notes by human evaluation (smell and taste). Both approaches ultimately rely on biology; specifically, the mechanism of human perception of aroma (smell). In the human nose, receptors detect a multitude of aromas, and sends signals of these aromas to the brain for interpretation. Each receptor is activated by different molecules and different concentrations of those molecules. The brain can then compile these signals into more complex concepts such as fruits.
The Recognition Skeleton
So how do Flavorists achieve these concepts? Using scientific methods, like Gas Chromatography, yields hundreds, sometimes thousands, of molecules (way too many to make a production viable flavor). By a purely creative process, there is not molecular information available to start a flavor. Here is where a concept called the Recognition Skeleton is utilized. What is the Recognition Skeleton? The Recognition Skeleton is a representation of a complex concept by a minimum set of specific compounds at the right concentration. This set of compounds is recognized by the brain as the complex concept (the sum of the parts), rather than the individual compounds used to create the skeleton.
Some flavors have a recognition skeleton of one or two compounds, where others require a more complicated skeleton. Some simpler recognition skeletons are flavors such as Vanilla or Cherry (both can have a recognition skeleton of one compound). Vanilla (will be explored in great detail later) can be represented by a compound called Vanillin, and Cherry can be represented by Benzaldehyde. Cherry will be re-visited below. One flavor type that is highly interesting to study within the Recognition Skeleton concept is Banana.
Banana is a very interesting flavor to discuss through the concept of Recognition Skeletons. Why? Banana has a compound that is highly reminiscent of Banana but not an authentic Banana: Isoamyl Acetate. Isoamyl Acetate has an aroma very similar to that of Banana Candy. Well why isn't this sufficient for the Recognition Skeleton? It is insufficient because it is not an authentic Banana. In order to achieve an authentic Banana Recognition Skeleton, only one more compound is needed: Eugenol. The addition of Eugenol is a peculiar addition by the fact that Eugenol smells of Cloves (it is the major aroma component of Cloves). Next time you eat a banana, grab some clove out of the spice cabinet and see if you can't pick up the clove note in the banana. A small amount of Eugenol added to Isoamyl Acetate will achieve the Recognition Skeleton of Banana.
Where Banana simply requires two compounds to achieve the Recognition Skeleton, other flavors, such as Strawberry, require a more significant variety of compounds. Disclaimer: Strawberry Recognition Skeletons can be achieved in many, many different ways. There is a saying I once heard from an older Flavorist: If you give 100 Flavorists a Strawberry Target, you will get 1,000 different Flavor Formulas.
The reason: Unlike Banana or Cherry or Vanilla, no one compound smells even slightly reminiscent of Strawberry (There is some debate on this but realistically, there is no individual compound that is immediately recognizable as strawberry). Because there isn't a compound to begin building around, several compounds must be employed to do the job. As such, as long as the basic notes are captured, the Recognition Skeleton can be achieved (meaning: many different compounds capable of achieving a note could be subsituted). The basic notes of Strawberry are Fruity, Sweet, Cheesy, Green and Creamy. For my example:
Fruity = Methyl Cinnamate (Fruity, Guava, Tropical, Slightly Spicy)
Sweet = Furaneol -or- 4-Hydroxy-2,5-diemthyl-3-furnanone (Sweet, Sugary, Cotton Candy)
Cheesy = 2-Methyl-2-Pentenoic Acid (Cheesy, Acidic, Dried Fruit)
Green = cis-3-Hexenol (Green, Fresh Cut Grass)
Creamy = gamma-Decalactone (Creamy, Peach)
I have written in parentheses how I would describe each compound. Next time you have a Strawberry, try to pick out each of those characteristics within the fruit. When these five compounds are combined at the right level, the Strawberry Recognition Skeleton is achieved. This example is one that I have used, but there are many others that can be employed.
Recognition Skeletons are the simplest possible representations of a complex concept. In order to achieve a more realistic concept, the flavor must be built out to include complex notes. In the above Strawberry, each component achieves the basic note required, but leaves much to be desired in adequately mimicking a true Strawberry. Strawberries are made of hundreds of compounds, many of which contribute to the aroma and taste of the Strawberry. Five compounds falls extremely short of displaying the nuances within a strawberry and each major note is made up of many nuanced notes. For instance, in the above Strawberry example, the green note utilized (cis-3-hexenol) is strongly reminiscent of fresh cut grass. This note provides a strong fresh green character to the Strawberry, but leaves out the rest of the nuanced character. In order to capture a more authentic green note, other compounds with slightly varied green character must be added to adequately capture these nuances. cis-3-Hexenyl Acetate could be added to capture a more sweet, fruity-like green character. trans-2-Hexenol could be added to capture a more leafy green character. As this is performed within each major note, the Strawberry flavor begins to come to life and the realism can be experienced more fully.
Cherry is another interesting case to explore, as it has a characteristic compound that captures the aroma of Cherry (Benzaldehyde). Benzaldehyde has a strong Cherry/Almond like aroma and can easily be linked to Cherry. However, to achieve a more authentic Cherry Flavor, more than just Benzaldehyde is necessary. The Major components of Cherry Flavor are Almond, Flesh, Pit, Fruity, and Acid. For my example:
Almond = Benzaldehyde (of course, Cherry, Almond)
Flesh = para-Methyl Anisate (Anise, Flesh)
Pit = Acetophenone (Pit, Cherry, Fruity)
Fruit = Ethyl Aceto Acetate (Fruity, Tropical, Apple)
Acid = para-Menthene-8-thiol (Acid, Sulfurous, Grapefruit)
The above example calls to attention how not everything within a flavor necessarily contributes to the major aroma, but can provide depth and realism in other ways. By utilizing components that contribute to minor characteristics within a flavor, the Cherry Flavor begins to mimic nature more closely, resulting in a more authentic flavor.
Ensuring that the Recognition Skeleton is accurate is key to creating an authentic flavor. Some Recognition Skeletons, like Banana, are very simplistic; created by utilizing only one or two components. Others are very complex, especially in the case of Strawberry. Once the Recognition Skeleton has been established, flavors can begin to take on more depth and character or achieve a truly authentic flavor profile.