The science of the senses
The brain’s ability to understand information from chemical substances has always been essential for our survival. Understanding this process is also essential for the arts of creating cosmetic and cuisine products.
‘Windows on the World: Taste and Smell’ is the third chapter of ‘An Odyssey of Flavours and Fragrances’ – the limited edition Givaudan anthology. In this chapter, chemistry professor Brigitte Proust explains the brain’s olfactory and gustatory systems, including what work is involved in appealing to these senses.
Something’s in the air
When we smell something, it’s because an odorous object has released some of its molecules into the air, which are then detected by our nostrils.
Above each nostril, we have a sensitive area (inside a mucous membrane) called nasal epithelial tissue. Imagine a tiny bed of sea anemones, constantly picking up molecules and sending information up to the brain.
The twin olfactory bulbs in our brains pick up this information and ‘light up’ a corresponding three-dimensional pattern, which the brain then uses to understand and remember the smell.
Measuring a smell
Our nasal senses are subjective and experiential. So we have to give it an odour value. We get it by dividing the odour concentration in the gaseous mixture by its threshold of detection.
The art of perfumery
Making a scent is like making music. An aroma has ‘notes’ that can be floral, fruity, amber-scented or spicy. There is perfect ‘harmony’ between heliotropes, vanilla and orange blossom, but also ‘dissonance’ between benzoin, carnation and thyme.
A perfumer must balance all these notes, using a mixture of natural and synthetic scents dissolved in ethanol, making up what is sometimes nicknamed the ‘juice’. The percentage of concentrates from natural and synthetic ingredients defines the mixture:
- 20 to 30% is a perfume
- 12 to 20% is an eau de parfum
- 8 to 12% is an eau de toilette
- 5% or similar is an eau de Cologne
How we taste
Each person has an average of 10,000 taste buds on their tongue, along with extra ones on their palate, pharynx and upper esophagus.
When a taste bud is stimulated, it creates a depolarisation, releasing a neurotransmitter that acts upon a sensitive neuron, which in turn transmits the information to the cerebral cortex, in the brain’s prefrontal region.
Types of taste
Our taste buds are particularly sensitive to five distinct categories of taste. Each of them plays a different role in telling our brains what we’re ingesting.
- Sweetness (glucose, sucrose, cane or beet sugar) identifies the rich nutritional elements
- Saltiness (sodium chloride or table salt) ensures the electrolytic balance of ingested elements
- Bitterness (hops, pure cocoa, quinine)
- Sourness (lemon, grapefruit) alert us to potentially dangerous food and
- Umami (Asian cooking glutamate) identifies the amino acids
The art of the flavourist
To design and create new flavours requires a deep knowledge both of the gustatory palette and of a country’s cultural trends and culinary tastes. Givaudan has created several tools to help with this:
- The Mood & Emotions programme matches the seven major emotions with tastes, creating a flavour profile based on the reactions the creator wants his or her new flavour to evoke.
- FlavourVision® is a trending tool. It takes into account a customers’ brand value to guide the creator towards flavours that harmonise with them.
It’s also important to know, and compensate for, how a product will be changed, chemically, by storage or cooking.
Although Givaudan has a collection of over 2,200 non-exclusive salty and sweet flavours, the true art is in evolving and adapting taste profiles. To do this, it’s all about collaboration – getting to know every customer’s needs in great detail and liaising back and forth until the formulation is just right.