Chef Heston Blumenthal had a eureka moment when he read, in Harold McGee’s book, On Food and Cooking: the Science and Lore of the Kitchen, that hot searing does not seal in the juices of meats.
This shocking truth encouraged him to adopt a different attitude towards cooking that boiled down to two words – question everything. Another key lesson Blumenthal took from McGee’s book was the value of a scientific approach to cuisine. The results, eaten in his 3-star Michelin restaurant, The Fat Duck in Bray, UK, brought him world recognition.
Initially, Blumenthal turned to textbooks for some advice. He was having trouble with his vegetables. The weighty tome Food Chemistry was a little difficult to digest, so he went in search of a chemist who could explain the science.
Eventually, he came across Peter Barham, a polymer chemist at the University of Bristol, UK, and said he was looking for someone to spill the scientific beans on what effect salt has on the colour of green beans. ‘He has no hang-ups that you must do things in the traditional way, and he’s open minded,’ says Barham, who asserts you only get a basic idea from a recipe, and that you should feel free to take good ideas and reject ridiculous ones.
Turkey roasts or boiled chicken?
For Christmas dinner, Barham usually cooks something fairly traditional. ‘Last year I had a bird’, he says. ‘But I did not roast the whole bird in the oven because it is very difficult to cook all the different components properly in an oven. I cooked the breasts in a water bath at a temperature around 58°C to get them nice and tender without overcooking. And I roasted the legs in a stock to ensure they too were tender’. The rest of the bird made stock for gravy, he recalls.
Barham explains that meats are challenging to cook well because their protein fabric is fragile. Proteins coagulate between 40 and 60°C, sticking to each other with water pockets trapped in between. When cooked at temperatures above their coagulation point, they stick together more tightly and this is why meat and fish quickly get hard and dry. ‘They become scrumptious between 55 and 65°C, but can go from juicy to dry in just a minute’, he says. According to another text by McGee, Keys to good cooking: a guide to making the best of foods and recipes, breast meat is low in connective tissue and is best cooked to 65°C for chickens and turkeys, or 57°C for ducks or squabs, but their leg meat is high in connective tissue and best cooked to 70°C. Meats become tender when moderate heat causes the proteins to bind loosely to each other and to water. Since most oven temperatures vary, it is difficult to predict correct cooking times, so it is best to check the temperature with a digital thermometer at intervals.
French chemist Herve This, an expert in molecular cuisine, is dismissive of the fashion for water baths. ‘My oven is good: if I want 61[°C], I get 61. And my dishwasher is very good, so I have two ways to cook,’ he explains. In fact, in 2010, This cooked his Christmas turkey in his trusty dishwater and he recommends the appliance for foie gras and salmon fillets too.
There are disadvantages to not roasting, according to Lisa Methven, food scientist at the University of Reading, UK, who delivered a festive lecture in December 2011 on the science behind Christmas dinner, organised by SCI's London Regional Group. ‘You get far more reactions occurring when you roast something than if you just boil it,’ she explained.
Flavourless proteins and carbohydrates react together to form hundreds of volatile aroma molecules when foods brown in the oven. Turkey has free amino acids and carbohydrates, which initiate these Maillard reactions, producing hundreds of different meaty flavours.
But you don’t need to be a carnivore to enjoy these reactions. Nut roast is an alternative way to generate similar flavour compounds, Methven said, and she recommends the inclusion of dried mushrooms and soy sauce to add some ‘umami’. The often forgotten fifth taste category – after salt, bitter, sweet and sour – umami is sometimes described as the savouriness of broth or stock.
Umami is the taste of the amino acid salt, monosodium glutamate (MSG), says Barham. Italian food bursts with umami because parmesan cheese, hard cheeses and processed tomatoes have enormous amounts of MSG. He explains that while less natural MSG is available in Asia, cultures there found a way around this shortage.
Eastern Asian cuisine, in particular, produces fermented fish sauce by recruiting microbes to grow on fish and transform its texture and flavour; the sauce preserves the fish and produces a concentrated source of savoury MSG and other amino acids. There is no evidence of ill effects from MSG, adds Barham. Those people who feel ill after eating Chinese food shouldn’t blame the MSG: ‘Give the same people an Italian meal, which is chock full of MSG, and they love it and aren’t ill,’ he says.
Umami, and MSG, it turns out, are also part of Christmas. ‘Stuffing will have quite a bit of MSG in it and cooked turkey will have some, and there will be some in the Christmas pudding. If you have cheese after-wards, there is plenty there,’ says Barham.
When it comes to carving your bird or joint, you should carve across the direction of the fibres or grain. This will minimise the length of the fibres in your guests’ mouths and make the meat easier to chew.
But Christmas isn’t just about roasted turkey. Barham says he usually serves roast potatoes with the main meal, but his are crispier than the norm. He explains: ‘It is easy to get nice and crisp roast potatoes if you vacuum dry them before you put them into the oven.
‘Put them under a vacuum for an hour or two to get the surface dried out. Then roast them, so you get them beautifully crisp on the outside.
And what wisdom for the accompanying the vegetables?
Keys to good cooking explains we can prevent a wrinkled surface on such vegetables as asparagus, green beans, carrots, and corn by coating them immediately after cooking with a little oil or butter. This prevents the hot vegetables from losing moisture and shrinking.
Methven revealed to her audience the science behind cranberries and Brussels sprouts.
Sprouts scare some of us away with their distinctive flavours, whereas some will delight in these pungent defensive plant chemicals, typical of the cabbage family.
‘We have a love-hate relationship with Brussels sprouts,’ said Methven, partly due to their bitter taste. The compounds responsible for that are mainly glucosinolates, but we vary greatly in how we perceive these compounds. Those of us with many papillae, or bumps, on our tongue, which contain the taste receptors, will feel the bitterness more strongly. But there is also a genetic component. We have 25 different bitter receptors, but only one of these (hTAS2R38) responds to glucosinolates. This receptor differs markedly between individuals.
‘If you are “bitter blind” then you have a genotype for this receptor that contains two insensitive alleles and so you miss that hit from your Brussels; if you have the two sensitive alleles you get the full wallop. Others are intermediate, as they have one of each allele – tasting and non-tasting. Dinner guests who are bitter blind to this compound won’t taste bland Brussels though, because there are other bitter compounds detected by different receptors.
However, bitterness is no reason to give up your greens. ‘Initially nobody likes bitter compounds, because they are a signal for toxins,’ explained Methven, ‘but we learn to like bitter things.’ Beer, coffee and dark chocolate are just a few examples of foods that we learn to like.
Methven also encouraged diners to try out the cranberry sauce. Cranberries are full of polyphenols, which are antioxidants and are potentially good for the heart and immune system. Phenolic compounds have also been shown to be good for attention and memory, as research done at the University of Reading has shown with blueberries.
Polyphenols are easy to spot, she explains. They bind to salivary proteins, so it can feel like the moisture is being sucked out of your mouth when the levels are high. Experiment by sipping red Bordeaux wine, which will give you a similar experience.
Ice cream or Christmas pudding?
Now for dessert, and a raid on the chemistry department might just prove useful. A good ice cream has a smooth texture, which comes down to the size of the ice crystals and the proportion of syrup coating them.
A balanced mix of ingredients and quick freezing produces small ice crystals coated with sweet, thick, concentrated cream. At –196°C, liquid nitrogen is up to the task.
‘If you make ice cream using liquid nitrogen to freeze the mixture,’ says Barham, ‘you make it at a very low temperature and make it very fast. The ice crystals don’t get a chance to grow large, so it is always going to be the smoothest ice cream you ever make.’
Barham adds that every chemist and physicist is comfortable using liquid nitrogen in the labs, and there is no reason for it to be locked out of kitchens. Last Christmas, Barham had a parmesan ice cream with parmesan crisps for the starter.
For dessert, he had the traditional Christmas pudding, though it would have been nicely matured, having been made five to 10 years previously. If you fancy something different, however, you could try a classic Blumenthal chocolate desert with a sponge type centre, inside which swirls a molten mix of blue cheese and chocolate.
And finally, to Blumenthal’s greens and colour. In The Fat Duck Cookbook, Blumenthal notes that Barham explained to him that chlorophyll – the green pigment in beans – is held in by magnesium. But this mineral can be replaced by calcium. So if you cook your beans in hard water, out goes the magnesium and the green colour. Forget about salt; there is a scientific explanation. And what better way to improve your cooking than to understand some of the science behind it.
Culinary gifts of knowledge
There are several books that cover the science behind cooking: The Science of Cooking (2001) by Peter Barham is one, or you could plunge for the encyclopaedic 800-plus pages of McGee’s On food and cooking: An encyclopedia of kitchen science, history and culture (2004).
A more accessible book from Harold McGee is Keys to good cooking: a guide to making the best of foods and recipes (2010), which is full of tips and tricks and the reasoning behind them.
Alternatively, there is Kitchen mysteries from Hervé This, which can be dipped in and out of with its chapters on soups, braising and bouillon, or The Flavour thesaurus (2010) by Niki Segnit, who takes us on a tour of flavour combinations.
For those with time on their hands, there is the lavishly illustrated but weighty book, totalling some 2438 pages, Modernist cuisine: the art and science of cookery by Nathan Myhrvold, Chris Young and Maxim Bilet (2011).
According to Barham: ‘It is the Bible for all of the things done in modern restaurants now,’ describing it as an absolute brilliant piece of work.
Anthony King is a freelance writer based in Dublin, Ireland.