Why is Ketchup so delicious?

...originally seen in The Observer

This is an excerpt from the article ‘Why is ketchup so delicious? Science answers the big food questions’ by Dr Ali Khavandi and Dara Mohammadi.

What makes ketchup so delicious?

Whether you’re a dolloper or a Jackson Pollocker, a plate of chips just isn’t the same without a good squirt of ketchup. But why does it make chips taste so much better? It’s the same reason Iberico ham is more moreish than the boiled stuff and why a sprinkle of parmesan makes a bowl of pasta that much fresher. The answer is the Japanese word for “savoury” or “deliciousness”, the fifth and most elusive of tastes: umami.

Taste isn’t only about deliciousness. Your tongue, like a little blind gatekeeper, uses taste to control what gets in.

Sweetness signals high-energy food. Saltiness means important electrolytes, which are vital to the functioning of every cell in your body, including those that keep your heart beating. Bitterness is a heads up that you might be eating poison, and sourness is a nudge towards citrus fruits and their vitamin C, or an alarm for rotten fruit.

What’s umami’s role? Its development during cooking or fermentation might show our bodies that food is safe and free of toxins. Maybe it’s a cue to important proteins? But to overcomplicate things would be to miss the point: if you’re having a dinner party, deliciousness is the first flavour you’re going to invite.

Umami is so important to depth of flavour that chefs’ tricks include browning meat and onions before slow cooking; adding a squirt of fish sauce or a generous squeeze of ketchup (a favourite of both Marco Pierre White and Jamie Oliver) to a stew; or adding dried porcini or shiitake mushrooms to give depth to a stock.

So essential is it that it has been bottled and sold as a time-saving product: monosodium glutamate, or MSG. It was discovered in 1908 by the Japanese chemist who coined the word for umami, Kikunae Ikeda. By analysing the brown crystals left after dehydrating kombu broth – made from kelp – he discovered the elusive umami taste was down to the presence of the amino acid glutamate. He stabilised it in its salt form, monosodium glutamate, and sold it as a seasoning.

The urban myth that MSG is unhealthy stems from a letter written to a medical journal in the 1960s, saying that it might be the cause of people having headaches and feeling unwell after eating in some Chinese restaurants. Despite some scientific study, nobody has found a link between MSG and any illness. And if MSG causes headaches, why doesn’t everyone in China have a headache?

A more likely link to unhealthiness is the use of MSG to add taste to cheap, tasteless, nutritionless foods such as instant noodles, where it’s labelled as E621. The synthetic form is chemically indistinguishable from the naturally occurring stuff, so there’s not even a theoretical reason to believe it would be bad. Glutamate, along with sugar, is abundant in human breast milk and helps guide a baby’s desire for food – a baby’s tastebuds are programmed to seek out both umami and sweetness. Speaking of which, glutamate is in the tomatoes in your ketchup, too.

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