What do we taste and why do we like food?

After returning from Japan, I was still buzzing from the food experiences we had over there and had bought several food ingredients to use at home for cooking. As I am a rather untalented cook, mostly I made variations of dashi to serve with soba (buckwheat noodles), a simple dish which my children and I enjoyed very much in Japan - and my version was a reasonable verisimilitude of the real thing.

But after a few days of soba, despite the variations (some were made with duck, pork, chicken, cold, etc), my wife gently leaned over and asked if I could cook something else instead for breakfast.

Initially, I was a little stunned - how can anybody turn down a bowl of delicious homemade soba? - but then it occurred to me that she was right. Not everyone can possibly always enjoy the same food as everyone else.

That might seem an obvious statement, but every human experiences food via taste buds and their noses - and most humans have pretty much the same basic set of taste buds and olfactory systems for smells. And yet our tastes vary so much and so passionately. With such relatively similar and basic tools, why does our sense of food enjoyment and preference vary so much?

So this issue became something worth investigating. When asked why people have different tastes, the most common answer is that it was built on social conditioning - French people would have croissants and coffee for breakfast, Germans prefer wurst, cheese and pumpernickel, Brits love sausage, bacon and eggs, Americans slather maple syrup over pancakes and meat patties, Chinese love a variety of spicy hot noodles and rice dishes, etc.

These preferences would be passed from parents to children - and to a certain extent, it is probably true. However, it does not explain the thousands of successful Asian restaurants in Europe packed with Europeans, nor the insatiable craving for pizza and burgers in Asian countries. If it was all due to childhood conditioning, many exotic restaurants would not survive - and there won't be major global fast food chains.

What's flavour, really?

Flavour is mainly what we enjoy when we eat food, and flavour is based on the interaction of taste buds and smells. There are also associated sensations which enhance the pleasure of eating - examples are chemesthesis (chemical stimulation of receptors that determines if something is spicy, minty, fizzy, etc), textural aspects on the tongue and mouth cavity (crunchiness, creaminess, etc) and other sensory inputs from lesser known taste cells that can detect fats, carbohydrates and kokumi (a recently discovered taste cell that appears to be stimulated by very slow Maillard reaction products such as aged cheeses and slow-cured hams).

So to find out why people enjoy different foods, a good starting point would be to identify the most basic groups or categories of ingredients or food textures that almost every human would instinctively enjoy eating.

A classic example would be ice cream - I have yet to identify any person who does not love a luscious, cold ice cream on a hot day. In fact, I have seen people in Berlin sucking on ice cones even in the depths of winter when the outside temperature was -15 degrees C. They were blowing on the ice cream to melt it a bit!

The study of what makes us like food has been researched in depth over the years. In 1825, Jean Anthelme Brillat-Savarin published a landmark book on gastronomy called Physiologie du Gout, ou Meditations de Gastronomie Transcendante; ouvrage theorique, historique et a l'ordre du jour, dedie aux Gastronomes parisiens, par un Professeur, membre de plusieurs societes litteraires et savants but in English it is shortened to just The Physiology Of Taste.

In the book, he treated the study of what he called the "pleasures of the table" as a science. The French were so impressed by his tome that they even named a cheese (Brillat-Savarin) and a dessert (Gateau Savarin) after him - and he made many astute observations which are still completely relevant today.

For example, he correctly identified in 1825, that the main causes of obesity in the diet were sugar and white flour. He also loved making pithy quotes such as "The discovery of a new dish confers more happiness on humanity than the discovery of a new star" and "A dessert without cheese is like a beautiful woman with only one eye" (he was clearly a man who liked his cheese platter).

The research continues to this day, of course. Nowadays, it is usually a big-budget research topic mainly conducted by the major food industries but much of the newest findings are not readily available to the public as it is commercially very valuable to know what flavours and textures humans like to eat - and especially how to synthesize flavour compounds and process food in novel ways to make them attractive and desirable to people.

And the research is not only about flavours, but also the textures we like to feel in our mouths, the colours we prefer and the temperatures at which we like to eat food. If the body is our temple, then there are people out there religiously researching every aspect of why we like our food.

Why we like food

Now that we have some background, let's investigate what makes food tasty and desirable. Not unexpectedly, the desire for good-tasting food is a combination of physiological and psychological reactions.

Here we will focus on the main physiological reasons why we like eating food - at least, these are the ones I have identified so far.

Treat these seven physiological factors like the strings on a guitar - the interplay of the psychological factors are the chords which make up the whole song. However, we will reserve that (long) topic for a later date as it is more complex than the physiological reactions - and most of them are just theories anyway.

Also, if you are an avid reader of gastronomy matters, you may have come across lots of books, recipes and articles on flavour-pairing. Many are fine articles in general and the flavour combinations are often rather original but I found the lack of scientific explanations about why certain taste pairings work somewhat disappointing.

And to be honest, a lot of the suggested combinations are purely subjective preferences rather than science - the reality is that what makes certain food pairings selectively attractive to humans usually fall under the psychological theories and simply cannot be explained easily.

Returning to those seven physiological factors, they are as follows, listed in no particular order of importance:

1. Taste hedonics - desirable food have to have certain combinations of salt, umami stimulants (such as MSG, guanosine monophosphate, inosine monophosphate, etc), sugar and some flavour-active compounds.

2. Dynamic contrast - "tasty" food must contain some form of contrasting textures or flavours. A crunchy deep-fried potato chip with a soft inside is an example. A sour and sweet lollipop is another example.

3. Conditioned response - a delicious food usually would have had some association with a past pleasurable event or meal, not unlike a form of Pavlovian response to some positive feedback situation. This may be partly the reason why most Germans like wurst in the morning while the French prefer croissants and coffee.

People tend to develop additional conditioned responses to new dishes and cuisines so the number of conditioned responses would very likely expand greatly over a lifetime. Chemical stimulation may also be involved, such as caffeine in coffee or phenethylamine in chocolate - as these chemicals are known to stimulate the brain.

4. Texture hedonics - good food usually has a certain texture or "mouth feel" that makes it desirable to eat. Everyone knows when the texture of a piece of meat or a slice of cake is just right for them. It is somewhat subjective but almost everyone has some preferences about the textures of the different foods they like to eat and it may be related to conditioned response.

In the evolution of humans, knowing the right texture of food in the past was very important to determine its suitability for eating, particularly for cooked foods. As an example, Austrians like a dish called tafelspitz, which is basically meat boiled to death and then boiled for a few hours longer after that. I had no idea why they would like this dish until someone told me that it was the way they historically cooked old, tough animals and they have simply gotten used to meat ruined by extreme over-boiling.

5. Food pleasure equation - in Palaeolithic times, humans ate food primarily for the nutrient content - and if something lacked sweetness, they would eat more of it to obtain more calories. This is not true now as we tend to eat a lot of food for pleasure, mainly because we have so much choice these days. However, the underlying intention is still nutrition and thus if we eat something with less calorific values these days, we tend to require stronger flavours to compensate for the lack of nutritional content, else we would not feel satiated.

Examples are fat-free yoghurts - they tend to have more sweeteners and stronger flavours than normal yoghurts. Similarly, if the calorific content is very high or the flavours are very strong, then we tend to eat smaller portions - examples are greasy bacon or sweets - though this is often not so true in modern times.

6. Calorific Density (CD) - if you have read an earlier article, you would be aware that humans actually have two brain systems. The one we are conscious of is the Central Nervous System (CNS, managed by the brain in your head), while the other hidden brain is the Enteric Nervous System (ENS) which is a 9m long collection of neurons that start from your throat and encompasses the entire digestive tract.

Part of the function of the ENS is to detect the CD in your food and feed this information back to your CNS so that you would know that the digestive system is happy with the type of food you're ingesting. The most satisfying CD for the human body is between 4 and 5, which is usually the exact CD found in most junk foods (0 is water and 9 is pure fat).

7. Emulsified food - humans tend to like the taste of emulsions, particularly salt-fat or sugar-fat emulsions. That is why we like the taste of butter, hot chocolate, salad dressings, sauces, ice creams, creamy mashes, etc. One reason is that emulsions tend to concentrate the taste of the hedonic compounds mentioned above into the water component of the emulsion.

This greatly enhances the taste impact on the taste buds (which tend to mainly process the water-soluble compounds). As an example, ice cream is an emulsified foam made with milk, sugar and flavours.

Being water-soluble, sugar gets consolidated in the water component of milk and when the tongue tastes the melted ice cream, it gets a very strong perception of sweetness from the dissolved (concentrated) sugar solution even though as a whole, the sugar content may not be very high in ice cream. However, on the tongue the strong sweetness is associated with the rest of the ice cream. The tongue would also get a stronger perception of the flavourings as well if they are water-soluble.

The past and present

In the distant past, these physiological factors obviously served the human race very well, else we won't be around now. But that was during times when the quantity and variety of food was strictly limited and often in short supply. These days, we can satisfy practically every gastronomical craving we get and satisfy it almost immediately - and this can become our collective Achilles heel.

As we all know, the modern easy access to junk food is at least a partial explanation as to why diseases like diabetes are increasing and why obesity levels are soaring around the world - but actually, that is not the whole story.