“Why One Person’s Taste Bliss is Another Person’s Poison" Prof. Tony Blake

“How Human Beings Learn to Like the Flavours of Foods and Drinks" Prof. Tony Blake

…..of the fruit of the tree which is in the midst of the garden, God hath said, ye shall not eat of it, neither shall ye touch it, lest ye die. ....but in spite of this warning Eve was typically human.

Humans are the only animals which cook and process the foods they find………… …...and in this way create new flavors which never existed before in Nature.

Humans eat the foods which they have created through their methods of cooking and cuisine. The flavors of these foods are dependent on the cooking processes used and are consequently man made. In human history there have been continual changes in food and flavor preferences

These are the remains of what is arguably the oldest flavour factory in the world. At Lixus in northern Morocco one can see the Roman factory which made Garum or Liquamem - a fermented fish sauce. Probably not dissimilar to Nuoc Mam a key food seasoning used in Thailand or the fish sauces still made by the Inouit Eskimos of Canada.

This is the pit into which the entrails of anchovies were placed This is the pit into which the entrails of anchovies were placed. They were allowed to decay and ferment to give the final product. Surely this is the oldest bio-reactor in the world.

The Evolving Scientific Base of the Flavor Industry 19th Century 20th Century 21st Century Solvent Extraction Molecular Separation Physical Chemistry Steam Distillation Identification Biochemistry Fractional Distillation Synthetic Organic Chemistry Human Physiology The flavour industry needed to evolve to meet the needs of the food industry. During the 20th Century organic chemistry became the science which expanded the capabilities of the flavour industry from one based on extraction to one based on analysis and chemical understanding.

For most of the 20th Century the focus of the Flavor Industry was the identification of those molecules which give odor and taste to food and drinks

New analytical techniques allowed these molecules to be identified at lower levels and with increasing precision

O H

S O Many sulphur compounds have powerful olfactive intensities. S-S’-ethylidene di thio acetate was identified in 1996 as the molecule which gives blood oranges their characteristic flavour.

Many foods that we eat have little or no flavour.

Until we cook them. The flavour of meat has fascinated scientists for centuries as it is made by a process that cows at least would consider unnatural. Man invented cooked meat and the flavours that come with it, so how natural are they?

This is just one compound isolated from cooked beef and with one of the lowest threshold levels ever measured - 10 -14.

Flavor Authenticity depends: not only on having the correct molecules but also an appropriate delivery system and the correct dynamics of delivery

In 1990 Firmenich purchased the Californian company MCP They had an enviable reputation in organic chemistry but lacked the science base for understanding the new products acquired with this acquisition

A Case Study in Flavor Release

Control of flavor release was an important marketing claim but one which couldn’t be quantified in the most important situation….

….during the eating of food.

In 1996 at the University of Nottingham Prof. Andy Taylor and Dr. Rob Linforth developed a technique for real-time, in vivo analysis of flavor release from food and this allowed a new understanding of flavor dynamics and the effects which food structure and composition have on its perception.

AROMA sweet sour PROFILE bitter umami salty We should not forget that flavour is complex and relies not just on the aroma of many thousands of volatile molecules but also the sense of taste - limited to only five dimensions. Sweet, salt, sour, biter and umami - the taste of monosodium glutamate.

Normalised sucrose and menthone release Perceived Intensity 120 120 100 100 80 80 Normalised sucrose and menthone release 60 60 Perceived Intensity Sucrose Release 40 Menthone Release 40 Time-Intensity 20 20 1 2 3 4 5 6 Time (min) Courtesy of J. Davidson & A J Taylor. The University of Nottingham

From Breslin et al Aroma-chology Review, vol. X n°2, pp14-17 (2002)

Almonds are not sweet

Mint leaves are bitter!

Our association of flavor and taste is learned. What do we taste each day that is minty and sweet? Our association of flavor and taste is learned.

What exactly is flavour ?

However, brains act in a holistic way...

… and we needed to get inside consumer’s heads

Magnetic Resonance Imaging

fMRI brain scans of people engaged in either hearing (blue) or silent lipreading (red). Common activity is shown yellow. From Calvert et al 1997.

Learning and Cross Modal Connections Propriosense Conscious Limbic Touch Hearing Vision Olfaction Taste Learning and Cross Modal Connections

The most plausible way to explain the inter-sensory effects we had observed is to conclude that ‘flavour’ is in fact a construct of the brain…….

.. and it is a learned response

> 80% of the input data is from breath from the mouth passing over the olfactory bulb in the nose, but what we see, how it feels, how it tastes, what we hear and our pleasure and satisfaction will all influence the way we remember it.

Flavour is a multi-sensory memory…. …… Flavour is a multi-sensory memory….. …….which depends on our personal experiences of eating and drinking…...

All our senses play a part in flavor perception Conscious Touch Hearing Vision Propriosense Olfaction Taste All our senses play a part in flavor perception

Flavor Processing: more than the sum of its parts. Small, D., Jones-Gotman, M., Zatorre, M.P. and Evans, A.C. NeuroReport 8, pp 3913-3917 (1997) Flavor processing is not represented by a simple convergence of its component senses….changes (seen with PET imaging) in the amygdala and basal forebrain suggest a role for these structures in processing novel or unpleasant stimuli.

Zampini, M. and C. Spence (2004 ). “The role of auditory cues in modulating the crispness and staleness in crisps.” Journal of Sensory Studies 19, 347-363.

Flavor is Nature’s way of letting food and drink communicate with us… …it tells us whether we can swallow what is in our mouth or if we should spit it out.

…..and we start learning about flavor very early in our lives, several months before we are born.

This baby already has flavour preferences which started to develop seven months before it was born.

Electron micrograph showing the extent and complexity of connections between neurons in the human brain.

Length of connections in the brain cortex in micrometres Taken from “Consciousness” Rita Carter 2002.

At birth 3 months 15 months 2 years Development of dendritic connections between neurons

Girl left with half a brain is fluent in two languages The Daily Telegraph, May 23, 2002

The Importance of Associative Learning

One would be hard-pressed to find a developmental neurobiologist who does not agree that early experiences, especially between mother and infant, influence the pattern of brain connections in ways that fundamentally shape our future personality and mental health. Professor Mark Solms Chair of Neuropsychology University of Cape Town South Africa

Our brains do not have the capability to form conscious memories until after the age of two, but the development of the brain in those first two years will greatly affect future attitudes, prejudices and behavior: - this will include future preferences for foods, drinks and their flavors.

The liking of wintergreen flavour depends on nurture not nature

Muscle-warming liniment or anti-septic ointment ? What does wintergreen remind you of ? Muscle-warming liniment or anti-septic ointment ?

Human beings like to experiment.

Monell Chemical Senses Laboratory Philadelphia Dr. Gary Beauchamp

Professor Leann Lipps Birch Center for Childhood Obesity Research

Prescott, J., Johnstone, V., Francis, J. Prof. John Prescott James Cook University University of Cairns Australia Odor-Taste Interactions: Effects of Attentional Strategies during exposure. Prescott, J., Johnstone, V., Francis, J. Chemical Senses 29, pp 331 - 340, (2004)

Professor Fergus Lowe

Dr Martin Yeomans

Sutton Bonington Campus of the University of Nottingham

Reproduced from The making of culinary tradition in Japan” J.K. Cwiertka. 1999

The Philippino Delicacy Balut The Philippino Delicacy

In which category do you fit ?

There is much that we do not understand about the human brain; the way it determines which foods and flavours we like is just one of the areas open for study.

A Voilley, Université de Bourgogne and P Etievant, INRA, France Flavour in food Edited by A Voilley, Université de Bourgogne and P Etievant, INRA, France Woodhead Publishing 2006