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.
Can food really affect bacteria in my gut?
Friendly bacteria in our gut help digest our food and keep bad bacteria at bay. Scientists, though, are just beginning to understand how this legion of microbes, known as the gut microbiome, contributes to our health. They play a key role in how our immune system functions and thus might help to prevent chronic diseases including diabetes. They orchestrate how genes are turned on and off in many cells and even affect appetite, weight and mood.
“The type of food you eat has the single biggest impact on your gut microbial community,” says Suzanne Devkota, a gastroenterology and microbiomeresearcher at Cedars-Sinai Medical Center in Los Angeles. The evolutionary template for good health, she says, was set when humans were hunter-gatherers and ate plenty of fibre-rich, plant-based foods. Bacteria feed off the fibre in vegetables such as spinach or kale and in beans and pulses, helping them make important short-chain fatty acids. These fatty acids, in turn, are used as fuel by cells that line our gut to keep it functioning well. They also communicate with cells in other parts of your body including the brain and organs in your immune system. “It may not be a coincidence that our major reduction in fibre consumption has coincided with the rise in many modern diseases,” Devkota says.
Tim Spector, a professor of genetics at King’s College London, and author of The Diet Myth, says compounds called polyphenols in bright berries and nuts are another source of food for microbes. Being too prescriptive about what you feed your gut minions won’t help, though. “Diversity is key,” he says. “Eat as many different types of healthy foods as you can.”
From studies that look at the guts of healthy people versus unhealthy overweight people, we know that a healthy microbiome is a rich, diverse one. It makes sense, given bacteria have 100 times more digestive enzymes than we do, that the more different types you have the more nutrients you’ll be able to strip out of your food.
Given this, cheap meat pumped full of microbe-killing antibiotics, says Spector, is something you want to avoid. It might also make you think twice about taking a course of antibiotics you don’t really need. Likewise, some preservatives, additives and artificial sweeteners might cause havoc. In evolutionary terms, our gut bacteria have never seen these chemicals. As they don’t know how to digest such chemicals, they can cause metabolic disturbances.
It’s not just some modern food production but modern ideas about eating that cause some people harm. The diets that tell us to restrict what we eat to lose weight – rice crackers and cottage cheese, anyone? – aren’t good for a blossoming gut microbiome. Obese people, who often have a less diverse gut microbiome, can be fussy eaters who eat few vegetables. So restrictive diets that starve your gut microbiome could explain why some people yo-yo on and off diets for ever.
A good guiding principle if you want a healthy gut microbiome – and by extension a healthy you – is to remember that you’re eating for more than just one, so have a little bit of what everyone wants.
How can something as tasty as fried food be so bad for you?
There’s an F-word even the bravest health bloggers daren’t mutter. It’s a word with such a bad image that even KFC rebranded itself to be free of its oil-splattered reputation. That word is fry. But what’s so unhealthy about the process? Is there anything we can do to make it less bad for us?
Whether fried, sautéed or roasted, we cook foods in fat because it makes them taste good. Fats reach higher temperatures than water, and at high temperatures chemical reactions happen that add texture and flavour – think seared meats, caramelised garlic, or crisp, battered fish.
If you cook like this occasionally, the extra fat you’ll eat is probably negligible to your health: it’s what you do to the fat when you heat it that counts. Like sending an astronaut into space, you need to choose the right vehicle – some fats will break down before they get to the temperatures you want. At temperatures below 180C (so sautéing, pan-frying or sweating-off vegetables) olive oil is a good choice. You’ll not get the full health benefits as in its raw state, but at these heats there’s no major risk of it degrading.
Polyunsaturated fats extracted from vegetables such as sunflower, corn, or soy oil are susceptible to degradation or oxidation when heated, and release toxic compounds such as the potentially carcinogenic aldehyde. A link to cooking with these oils and developing cancer has never been shown, but knowing a risk exists suggests it’s wise to steer clear. The same can be said about acrylamide – a chemical produced by excessive browning, or burning, of starchy foods such as bread or potatoes which has received recent attention after it was found that giving enormous amounts of it to mice gave them cancer. Such studies tell us little about its effect in a human diet. Still, a sensible approach would be to brown food and not burn it: a mantra any chef should be OK with.
On polyunsaturated fats, even when raw, some researchers think the high omega 6 content in these oils can lead to chronic disease of both body and mind. Get your protective polyunsaturated fats from whole foods high in omega 3 – nuts, seeds and fish.
For high-heat searing, roasting or deep-fat frying, where oil is heated to higher temperatures or for long periods, go for saturated fats like animal fats. These are more stable at higher temperatures and, as a tasty bonus, can get your food up to those stratospheric temperatures for taste: it’s why goose fat makes the crispiest potatoes. Rapeseed oil is a stable monounsaturated fat with a great theoretical profile for cooking, but we don’t know much about its long-term effect on health.
Before we free the clarified butter and lard from the shadowy corners of our cupboards, we should remember that frying is by no means healthy. High-heat cooking produces plenty of tasty chemical reactions but it might also produce some potentially unhealthy ones. In lieu of solid evidence about the health effects of dietary aldehyde and acrylamide, we should accept that there might be some risks but ameliorate them as much as possible by using the right fats.
Is fresh always best?
If you asked someone a decade ago about bacteria and food they might have thought of a time-lapse video of a rotting sandwich. Our understanding of the interplay between bacteria and food is now more sophisticated. We know that fermenting foods makes them taste good. And some people think it might even make them healthier.
To understand the role of fermented foods in our diet it helps to understand their original purpose. Kimchi, kefir, yogurt, beer, cured meat, cheese and wine – they’re all fermented and all predate refrigeration. During fermentation, bacteria or yeast convert carbohydrates into acids or alcohols, natural preservatives that keep food for longer. That it improved the taste – or in the case of alcohol gave drinks other pleasurable side-effects – helped the process catch on.
Like cooking, fermentation helps break down components of food we’d otherwise find difficult to digest: it’s why an aged steak can melt in the mouth. And with easy digestion comes easier absorption of nutrients and thus benefit for health. The fermentation process also creates new nutrients such as vitamin B.
The much-touted health effects of eating the bacteria in these foods is less clear. “There’s a big debate about whether fermented foods have a proven beneficial effect and if so what the mechanism is,” says Tim Spector. “Most people have found that the bacteria you ingest don’t stick around for too long, but there’s a consistent suggestion that they might still do some good.”
Given that people eat so many different types of foods over their life, teasing out any benefit of one thing is difficult. Still, says Spector, although we lack high-quality data, long-term observational studies have shown beneficial long-term health outcomes such as reduced heart disease in people who eat, say, live yogurt compared with those who don’t, even when potential confounding factors such as regular consumption of junk food are accounted for. “They don’t become permanent residents, but we think the bacteria might have a beneficial knock-on effect on others in your gut.”
With so much unknown about the effect of ingested bacteria, it’s probably not worth a healthy person taking specially branded probiotic products, such as the theoretically beneficial vials of live fermented milks or the probably useless capsules of dried, dead bacteria. And it would be wise to apply the same principle to any one fermented food. Eating plenty of one type of fermented food alone may not give you a special health benefit. Eating a range of fermented foods, especially fermented vegetables, will add variety and flavour to your plate, letting you pack in even more nutrients and fibre into your diet.
Sourdough isn’t better than regular bread, just more fashionable, right?
Goldilocks and The Three Bears isn’t the only story to start with a bubbling bowl of porridge. Around 6,000 years ago, a baker noticed a bowl of flour and water that had started to bubble. Baking it anyway, he pulled from his oven not the flat bread he was expecting but leavened, textured sourdough.
Mixing with the flour and water, the wild yeast and bacteria in the air had triggered a fermentation process that breathed life and taste into bread. In the 1960s, bread manufacturers devised a cost-effective way to make more of it. They dispensed with the lengthy natural fermentation process by adding more gluten, the protein in wheat that gives bread its chewiness. They used white flour, stripping all the goodness out of whole wheat, then shovelled other apparently fortifying nutrients back in, which along with added preservatives, they used to market their tasteless product as superior to the bread a local baker might make. They aimed for a Superman bread but ended up with a Frankenstein one.
David Sanders, author of Gluten Attack and an NHS gastroenterologist, reckons one of the reasons we’re seeing an increase in gluten intolerance might be the high gluten content in industrially produced breads. “Many patients with gluten intolerance tell me that when they have sourdough they don’t have a bad reaction like they do with other bread products,” he says. “Maybe it’s because the natural proofing process breaks the gluten down better or more likely it’s all the extra gluten they’re spooning in.”
So too, says Sanders, are we seeing more gluten intolerance and allergy in India and China as people there switch to a more Western diet, swapping rice for supermarket breads, pizzas and pastas. It’s easy to point the finger at one culprit, gluten, but it’s also been part of our diet for thousands of years. Let’s not forget there’s money to be made in providing gluten-free alternatives. A bigger problem, perhaps, is some food production; stripping nutrients out and putting others in, solving one profit-making problem by creating another.
By selling us convenience, the food industry has skewed our perception of how long we should spend preparing our meals so that traditionally prepared food is somehow fashionable – that many people see sourdough, the original leavened bread, as a fashionable product would attest to that. The story of bread and industry should be a cautionary tale. Not all foods need to be made in Grandma’s kitchen, but we should be wary of food that has had nutrients squeezed out to make room for profit.
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