Photo: Ryann Cooley Photo: Ryann Cooley
When it comes to dining, most people trust their tastebuds. Food, after all, is food and there’s no fooling that hardwired, primeval sense of taste or flavour.
Or is there?
To put this popular notion to the test, food scientists at Monash University designed a short but telling experiment. A sensory panel of four tasters was presented with exactly the same recipe for a chicken mango curry. The meal was served randomly in four ways: on a large square plate, a normal-sized circular plate, a small bowl and in takeaway foil.
Although two chefs cooked the meal, the tasters were provided with food prepared by only one chef, leading the tasters to believe there might be some subtle nuances in flavour.
The results were intriguing. Despite the food being identical, all four participants reported distinctive variations in the meal’s smell, taste, flavour, appearance, texture and after-taste.
Ratings of appearance and smell were weakest in the case of the takeaway foil and strongest for the normal-size round plate. Most tasters reported that the curry on the large square plate was bland, although they felt it had the most agreeable texture. In contrast, the food dished up in the small bowl was deemed to have the strongest and longest-lasting flavour.
The sample size was too small to be statistically analysed. but it seemed clear enough that something made the same food taste different when presented in varying ways.
“This simple experiment clearly shows that our oral sensors are influenced by what we observe,” says Monash University dietetic researcher Ricardo Costa. “For example, the fact that curry in the small bowl tasted strongest suggests a more concentrated sensation in response to food presented in a more condensed fashion.”
The findings accord with a burgeoning body of scientific research demonstrating that the human senses interact and combine to form an overall impression of experiences. Taste is no exception. So the sounds we hear, and the shapes and colours we observe, markedly influence the flavour of food and drink.
“It is an area of research only flourishing in recent times,” says Dr Costa. Research, he adds, is now beginning to explore the influence of cutlery texture on flavour – such as whether a fork or spoon is made of plastic or metal.
The same principle applies to drink. Water presented in a cool-coloured glass, such as pale blue, may seem more thirst quenching. But in a yellow glass, for instance, the water may taste less refreshing.
“Certain colours are associated with events in nature – for instance, red or yellow with fire, blue with cool water, green with refreshing leaves. Bright and vivid colours, on the other hand, signify dangerous poisons, perhaps,” Dr Costa explains. “This may predispose people to having a particular perception before consuming a meal or drink.”
Working in tandem
The sense of taste refers to five main qualities: sweet, sour, salty, bitter and umami – a fondness for savoury substances triggered by certain amino acids and nucleotides, says Deakin University sensory scientist Russell Keast. “We know the senses work together to form a perceived sense of flavour – so there is plenty of opportunity for one sense to influence the perceptions experienced from a second sense.”
For example, adding a strawberry aroma to a sucrose solution makes it taste sweeter than sucrose alone. “If we are concerned about excess consumption of sugar, this type of information allows us to reduce the level of sugar while maintaining sweetness, which we all like,” Professor Keast says.
People also need to be able to separate the pleasure derived from sweet foods from the quality of sweetness, he says. “They are independent systems and can easily be disentangled from each other.”
The context in which a meal or drink is consumed also influences flavour. “I like a beer after mowing the lawn, but if given the same beer when I awake at 5am, I don’t like it, even though the beer is the same,” Professor Keast says.
Food scientists have also identified something called the dose-response effect. “A pinch of salt in a bucket of water cannot be tasted,” he says. “But the same quantity of salt added to a stew really heightens the flavours, while again the same quantity sprinkled on one potato chip would be excessively salty and unpleasant.”
Taste itself is just physiology, says Baker Institute biochemist Merlin Thomas. “Taste molecules bind to taste receptors, setting off nerve impulses that go to the brain, and so forth,” Professor Thomas says.
But the ways we interpret this taste, he says, are determined by factors including age, gender, past experiences and associations, mood, the setting and whether or not one is hungry. Even music can play a part.
“Although shape, colour and texture don’t affect physiology directly, they influence our interpretation of these impulses,” Professor Thomas says.
It is well known, he points out, that when participants take part in the same taste test but in complete darkness, or wearing tinted lenses, remarkably different results are obtained.
Expectations also play a crucial role in how flavour is experienced, says Cambridge, Massachusetts-based food author Jeff Potter.
“Food shapes, colours and textures have in common the perception of how what we expect something to be lines up with our sensory input,” Mr Potter says. “For instance, if you’re looking at an apple and expecting it to be crisp, a little tart and juicy, and instead you get something mealy – well, it’s not enjoyable,” he says. “That’s not to say things that crumble and are mealy always taste bad. If you were biting into baked potato and it was crisp – instead of having that fall-apart texture related to mealy – that’d be bad too.”
People are satisfied when foods conform to their expected taste, smell and texture, he says, but may be surprised when they are different. “Sometimes that surprise can be fun and novel, and some high-end restaurants pull this off with the modernist culinary stuff.”
British celebrity chef Hestor Blumenthal, famed for experimenting with a range of dishes in his restaurant The Fat Duck, springs to mind.
“But usually it’s the opposite,” Mr Potter says. “And we’re disappointed when we don’t get what we’re expecting.”
Mr Potter describes a landmark study in which scientists altered the colour of some 70 foods. With the exception of bacon, subjects found that odours appealed more when colour was “normal” for that dish.
In the US, some high schools conduct simple experiments on food and perception. In one, orange dye is added to clear soda and compared with orange soda. “Obviously the clear soda and orange dye shouldn’t have a fruity orange taste, but the colour suggestion can be strong,” Mr Potter says.
Experiments on taste began in the 1930s, when a scientist at the chemicals company DuPont accidentally spilled a compound called phenylthiocarbamide on his lab bench and a co-worker complained of experiencing a bitter taste.
“Like any good scientist, the chemist started giving samples to various people, and watching what happened,” Mr Potter explains. The research found that one in four people tasted no bitterness.
More recent work concludes that people divide into two groups: super-tasters who find phenylthiocarbamide unbearably bitter and others who find it less bitter or not bitter at all.
“There are other compounds, such as caffeine and nicotine, that are chemically similar to phenylthiocarbamide and which some people find bitterer. As a result, they tend to avoid such substances.”
It seems super-tasters have inherited certain characteristics from their parents, Mr Potter says. “The percentage breakdowns differ by ethnicity and gender.”
White females, for instance, have a 35 per cent chance of being super-tasters, while white males have a 10 per cent chance. Asians, sub-Saharan Africans and indigenous Americans are much likelier to be super-tasters.
Feeling the heat
Temperature also plays a crucial role in the way food tastes. Take a vanilla cake. “The recipe says set your oven at 175 degrees and bake for 25 minutes,” Mr Potter says. “Why can’t you set it at, say, 300 degrees and bake it in just 10 minutes?”
For vanilla cake, certain heat-dependent chemical reactions are needed, such as getting the water in the batter to steam up or getting the baking powder to generate air bubbles to make the cake light and airy.
“We also want to ensure other chemical reactions don’t occur at temperatures higher than 175 degrees,” Mr Potter adds. “So, if you set your oven at 300 degrees, such reactions would ruin the taste.”
Learn about Ricardo Costa
Follow the exploits of Russell Keast
Delve into Jeff Potter’s book Cooking for Geeks
Tuck into top-notch tucker