Discovering the magic ratio
Human breast milk contains all but one of the essential nutrients that our bodies need – it’s just potassium that’s missing. For most of us, it’s the perfect start to our lifelong relationship with food. So it seemed like a good starting point for our series.
One of our producers had a friend who was expressing milk for her newborn, and kindly donated a bottle so we could deconstruct it in our lab. I had a sip, more from curiosity than anything else. It tasted like a sweeter version of cow’s milk. Or almond milk. For obvious reasons I didn’t linger on the thought for long!
One of the things I find really interesting about breast milk is that it contains a secret that food manufacturers have exploited to get us “hooked” on their products. It’s the magic ratio of 2:1, carbs to fat.
In 100ml of breast milk there are roughly 8g of carbs to 4g of fat. You will find the same ratio of carbs to fat in many of the foods that we find so hard to resist, ranging from chocolate and biscuits to ice cream and crisps.
Unlike these highly processed foods, breast milk is, of course, the ultimate home-made food. It is tailor-made for babies, who need lots of energy to grow. And unlike the fats that you find in processed foods, the fats that come in breast milk are nutrient-rich – they’re “good” fats.
So one of the reasons why we find processed food so irresistible may be because we’re reminded of the first food we ever had.
For the series we tested strawberries and discovered that they have only half the sugar of blueberries. Yet they taste sweeter. Why? Well, strawberries are surprisingly devious. They give off aroma molecules that trick our brains into thinking they contain more sugar than they really do.
On the one hand they need to be sweet enough to be eaten so that in the wild, their seed is spread through animal droppings. But they also want to conserve some of the energy that would go into developing a sweeter flavour in order to reproduce and grow.
Long ago the strawberry plant discovered that a good way to make its fruit more attractive, without having to give away too much precious sugar, is to pretend to be sweeter than it is. It’s a neat trick that a handful of other fruits have pulled off, including raspberries, pineapples, lychees and peaches. If we can learn exactly how they do it then this could help food scientists find ways of reducing the sugar content of our foods.
Why tomatoes are the best fruit
Umami is a Japanese word that translates as “pleasant savoury taste”. It’s the most recently discovered of all the tastes. The umami taste tells our bodies that the food we are eating is rich in an important amino acid called glutamate. Amino acids are the building blocks of proteins, which in turn are essential for building muscle, blood cells and the cells of our immune system.
One reason why MSG – monosodium glutamate – is such a widely used additive is because it’s our tongue saying to our brain, “Mmmm protein.”
Tomatoes are the most popular fruit in the world, possibly because they are also the richest in umami. But if you want to taste one of the most umami-rich foods of them all, then you need to head – as we did – for the oak forests of south-west Spain, home to the black-footed Ibérico pig.
While they are growing, these pigs roam the forests, gorging on fat-rich acorns. These give the meat a gorgeous fatty shell, which protects the ham while it cures. We were able to show how the cells break down deep inside the ham into more and more glutamate molecules, creating an incredibly intense umami flavour on the palate. Parmesan is another that is incredibly high in umami.
Making this series has been a real education. I came across lots of fascinating research into the different ways our sense of taste guides us towards what is nourishing and away from what is harmful.
Interestingly, we have around 20 more types of bitter receptors on our tongues than sweet receptors, which suggests that way in the past humans’ overwhelming need was to be aware of poisonous foods, which often taste bitter. Put simply, our sense of taste has evolved to be our mouth’s gatekeeper.
The Secrets of Your Food is on tonight at 9pm on BBC2