The Science of Food by Marty Jopson
You may be familiar with Marty Jopson from the occasional science films he does for programmes like The One Show. He may have become an entertaining science boffin on telly and stage with his live show, but he has a PhD in cell biology and his mother was a cookery teacher, so he is well placed to write a popular science book about food.
After the introduction, Jopson starts by taking a look at ‘The Essential Technology of the Kitchen’. Eschewing all the useless things we all have drawers full of, we look first at the ‘ultimate kitchen gadget’ – the knife. The Materials Scientist in me loved this – chopping and slicing is all about shear. He explains why blunt knives don’t shear, requiring more force which is why they are more dangerous. We discuss what kind of steel makes a good knife – you need a sharp edge that stays sharp – to get the hardness to toughness balance right. Then there is the angle of the blade to consider – the Japanese-style blades are narrower but more prone to getting damaged. He goes on to discuss chopping boards – the wood versus plastic debate. It transpires that as long as you use hot soapy water to wash and throw it away when it gets scored/split – there is no difference on the hygiene side. Discussions about saucepans, pressure cookers, water baths, fridges and whisks follow – no mention of the microwave though!
We’re ready to start looking at food now. The magic of processed food first. We’re drawn in by Jopson’s explanation of the frankly bizarre lengths they have to go to to make puffed wheat (aka Sugar Puffs), before settling down to look at some key ingredients and processes. He clearly explains what modified starches are used for in the food industry – from thickening to giving good shelf-life etc before moving onto the Chorleywood process for making bread which solved a big problem in British agriculture:
Here in the UK, we have a problem when it comes to growing wheat, the raw materials needed to make bread flour. It’s just not cold enough in our winters. … Because of this, almost all of the wheat grown in the UK has a low protein content, generally only about 10 percent of its weight. Unfortunately, that is not enough gluten to make good bread. For that you need at least 13 percent protein, and ideally a bit more, in your flour.
Different varieties of wheat produce different quantities of gluten in their seeds. But all of the high-gluten varieties need a period of deep cold to get the best protein content – a period of deep cold that the UK just doesn’t get. This process is called vernalization. … Winter wheat that has been successfully vernalized produces hard wheat, which in turn makes for strong flour. Conversely, almost all wheat grown in the UK is soft and only useful for pastry flour.
The Chorleywood process, named after the village where it was developed, uses intense kneading to put so much energy into the dough that it overpowers the gluten’s tendency not to stick together. This chapter continues by looking similarly at emulsifiers, sweeteners and freeze-drying.
Then we move on to the real magic that happens when you cook food due to chemistry. Jopson explains the two crucial reactions that occur which give our cooked food the flavours we adore. Firstly, the Maillard Reaction which starts at around 140C – the different sugars in foods combine with amino acid proteins to give us those roasted or nutty tastes and browned colours. Secondly caramelisation of sugars which starts at slightly lower temperatures. He also discusses chocolate, Brussels sprouts, caffeine and more, delving into the chemical reactions and physical properties that make these foodstuffs so distinctive in our diet. There are lots of chemical constituents named in this chapter, some many times, and the reactions that create taste, flavour, aroma are complicated, but Jopson explains them well backed up with other interesting facts.
The next section is about bugs – bacteria. He starts by quoting the folklore that is the five second rule about eating food that has been dropped on the floor. The correct answer is that of course it’s utter nonsense, As soon as the food touches the floor it is contaminated. It only takes a few E.coli bacteria to make you very ill indeed – that is the risk you take. Arguably if it is a dry food onto a clean floor the risk is smaller, but do you want to risk it? This chapter goes on to discuss gut bacteria briefly before moving onto pasteurisation, fermentation and fungi.
The final part looks at the future of food – from the challenges for the world to produce enough protein for everyone, eating insects, a little about genetic modification, new farming techniques such as hydroponics etc. before closing with the story of the horsemeat as beef scandal which was discovered after advances in DNA testing.
Jopson is an entertaining host. There is enough real science in this book to satisfy those, like me, who have a scientific background. I’m no biologist though, so once beyond the materials-based discussion of kitchen gadgets, I did learn a lot about food processing and the essential science behind “what we eat and how we cook”. You don’t need to be a scientist to enjoy this book though – you’ll find that when you’re cooking, you’ll realise that a pan’s not hot enough for the Maillard reaction when a steak doesn’t brown, or what’s happening when your caramel crystallizes or your chocolate seizes – something Bake-Off constestants could benefit from perhaps? Dare I say it, this book would make a good gift for interested foodies. (8/10)
Source: Publisher – Thank you
Marty Jopson, The Science of Food (Michael O’Mara, Sept 2017) hardback, 224 pages.