Eye watering: A school teacher has created a number of infographics to explain the chemistry behind everyday food includingwhy onions make us cry. None of the compounds that cause people's eyes to water are present in an intact onion, but when the cell walls are damaged by chopping, an enzyme released produces a range of compounds as a defence mechanism, which act as irritants
'Chemistry gets a pretty bad reputaion at times, with the word "chemicals" too often used to denote something bad. I want to show that chemicals are in fact in everything, in all the foods we eat and responsible for some pretty interesting effects,' he told MailOnline. He also sells his creations from his Compound Interest blog.
For example, asparagus causes the urine of some – but not all – people to smell and for 40 years scientists have tried to pinpoint the chemical compounds responsible. While there is no definite verdict, it is thought they are all compounds formed by the breakdown of asparagusic acid.
It is only found in asparagus and scientists think it is metabolised in the body to produce the volatile compounds found in the urine after consuming the vegetable.
A technique called gas chromatography-mass spectrometry was used to analyse the gas nearby urine after the consumption of the vegetable, which showed odour-causing compounds were produced not usually found in normal urine.
The primary compounds present, in quantities a thousand times greater than in normal urine, were methanethiol and dimethyl sulfide. The compounds dimethyl sulfoxide and dimethyl sulfone were also found and might modify the aroma to give it a ‘sweet’ edge.
The ability to smell asparagus-influenced urine is not universal and research has shown that two out of 31 people could not detect the difference in smell. It has also been proven that not all people produce smelly urine after eating asparagus.
The chemist also explained why onions make humans cry. None of the compounds that cause people’s eyes to water are present in an intact onion, but when the cell walls are damaged by chopping, an enzyme produces a range of compounds as a defence mechanism, which act as irritants.
There are a wide range of compounds produced by these reactions and if the onion is eaten, they are broken down into allyl methyl sulphide, which can be removed from the body by exhalation – giving rise to the characteristic ‘onion breath’.
The scientist also explains why nutmeg has been used as a hallucinogen since the 16th century.
Myristicin makes up around one per cent of raw nutmeg and scientists think it leads to the effect because of the breakdown of the compound in the liver into MMDA, a drug of the amphetamine class and a known psychedelic.
However, the spice also has undesirable effects such as vomiting, flushing and an elevated heart rate that can last for several days.
The blog also lifts the lid on why grapefruit interacts with some medicine. A family of chemical compounds called furanocoumarins, as well as bergamottin and dihydroxybergamottin interfere with the activity of an enzyme that plays an important part in breaking down some drugs in the body and when prevented from doing so it can lead to high levels of concentration of the drug in the bloodstream.
This is a problem, because prescriptions for drugs take into account the rate at which the body breaks down the drug in their dosage recommendations.
Eating a grapefruit while taking some medications can be enough to cause significant interaction with enzyme activity and the side effects can potentially include kidney damage, blood clots and breakdown of muscle fibres, the chemist warned.
The blog also addresses why chocolate is toxic to dogs, the chemistry of tea and its antioxidants, why coffee is bitter and lemons taste sour.
Citric acid as well as a number of other compounds such as malic acid gives the lemon its sour taste. Malic acid is also found in apples and cherries, and responsible for aspects of their flavour.
Strangely, coriander, or cilantro, tastes soapy to some people and this is because the essential oil in the leaves is composed of 40 different organic compounds including aldehydes, which are largely responsible for the herb’s smell - and soapy taste for some.
It has been suggested that genetics play a part in why some people think the herb tastes soapy and why others do not. Scientists have highlighted a specific gene that codes for a receptor that is highly sensitive to the flavour of aldehydes.
Original article and pictures take http://www.dailymail.co.uk/sciencetech/article-2599758/Why-asparagus-makes-urine-smell-onions-make-cry-Infographics-reveal-truth-strange-effects-certain-foods.html site