Dr Kathrin Ohla detested brussels sprouts, so she forced herself to eat them every day for a week.
Is she a machochist?
Maybe, but mainly she’s a psychologist whose research focuses on understanding how the human mind processes food.
She says that she has “always found brussels sprouts unbearably bitter”.
But since she constantly heard they were highly nutritious, she did a self-experiment to see if she could get used to their taste.
One of the many important findings by taste researchers like Dr Ohla and Dr Maik Behrens, head of the working group on taste and odour systems reception at the Leibniz Institute for Food Systems Biology at the Technical University of Munich, is that food preferences can change.
What doesn’t change, however, is whether foods such as brussels sprouts and broccoli taste very bitter to you – this is inherited.
“Detection of certain bitter compounds has a genetic basis,” Dr Behrens says.
People who carry the TAS2R38 gene in a fully-functional form, which “most people do”, can intensely taste these compounds.
But about 30% of the population are “non-tasters”.
Another peculiarity of the sensation of bitterness is on our tongue.
The tongue’s papillae contain taste buds with 25 different kinds of bitter taste receptors.
For the other basic tastes – sweet, sour, salty and umami (savoury) – there are typically just one or two.
The taste receptors are dispersed all over the tongue, with an especially large number of bitter taste receptors at the back.
“This makes sense,” says Dr Ohla, because stimulating this area also stimulates a nerve that can trigger the gag reflex – a protective response to prevent foreign objects from entering the throat and to expel inedible or toxic substances.
“Everything that activates the taste buds is relayed via nerve fibres to the brain, where a taste sensation is then formed,” Dr Behrens says.
In common parlance, many senses are involved in taste, he notes, adding that “not without reason do we say that we eat with our eyes first”.
The sense of smell plays a greater role though, more specifically what’s known scientifically as retronasal olfaction.
Odours emanating from the oral cavity during eating and drinking pass through the upper part of the throat and are picked up by smell receptors in the nasal passages, contributing to the flavour of foods and drinks.
This is why we can’t taste as well when we have a stuffy nose.
As Dr Behrens clarifies: “In fact, we can’t smell as well.”
And contrary to what you may think, “hot” or “spicy” isn’t a taste, as the sensation doesn’t arise from our taste buds.
”It actually comes from stimulation of nerve endings (for touch, temperature and pain) in the oral cavity, such as also occurs on the skin,” he says.
“Spicy isn’t a taste, but a pain or temperature sensation,” says Dr Ohla.
And no matter how you slice it, there are some foods that lots of people turn up their noses at.
Take the herb coriander, for instance.
“Some people say it tastes like soap, while others find it quite pleasing,” Dr Ohla says.
As she explains, the main reason for the former isn’t a difference in the taste receptors on their tongue, but a variation in a group of olfactory-receptor genes that allows them to strongly perceive soapy-flavoured organic compounds in the leaves.
Besides genetics, the extent of a person’s exposure to certain foods affects taste perceptions.
“Socialisation plays a role in food preferences too,” says Dr Behrens.
“In Asian countries, for example, where coriander is much more commonly used, there are far fewer people who reject it than do here.”
It’s conceivable, he surmises, that acceptance of this plant could increase in places where it isn’t as popular, such as happened with garlic when people started to come into contact with it at a much earlier age and more often, and gradually grew to appreciate it.
“You can get used to almost anything,” says Dr Ohla.
“Psychology can override genetics.”
Her self-experiment with brussels sprouts was a success.
“It was really bad the first few days,” she recalls.
“But now it’s one of my favourite vegetables.” – By Katja Sponholz/dpa