Science - May 10, 2012

From molecule to meal

Anyone who cooks is involved in fascinating chemical and physical processes, often without realizing it. You can read about these processes and how you can use that knowledge to your advantage in the book The Kitchen as laboratory, containing the latest insights about molecular cooking. Our question was: does it work?

Mmm..., scientific food tastes good.
Can you make ice cream without using sugar? How do you get the tastiest bacon? And why does cold milk froth more than hot milk? You will find the answer to these culinary questions in The kitchen as laboratory, which was published in January. The science behind eating is the subject of this collection of essays, put together by Erik van der Linden, professor of Food Physics, and others.
Van der Linden and his co-authors were inspired by Nicolas Kurti's book But the crackling is superb that appeared in 1988. 'Nearly a quarter of a century on, we wanted to give an updated picture of the current state of affairs', says Van der Linden. He is not keen personally on the term 'molecular gastronomy', which he feels evokes images of stagey cooking using liquid nitrogen. He prefers to talk of science-based cooking, in which cooking practices are based on knowledge of food at the molecular scale.
Of course the million-dollar question is: What are the benefits? Do meals taste better as a result? To find out, two Resource editors with little in the way of cooking experience tried out some recipes in the kitchens of the Restaurant of the Future.

The tastiest cookie
We start by having a go at the perfect dough for chocolate chip cookies. Cookery experts know you get the best cookies by using dough that has stood for a day in a cold place. That allows the moisture to disperse properly and gives a fuller, more complex flavour. The book argues that you get the same effect by sucking all the air out of the dough to create a vacuum; the moisture spreads immediately because the porous dough exerts an attraction on the water molecules.
We combine the ingredients to create a lump of dough, then seal half in a plastic bag. There is a clear difference between the two halves. The standard dough is dry and light brown but the vacuumed dough is creamy and dark.
There is still a big difference when the cookies come out of the oven. The cookies made from the standard dough are light brown, dry and crispy whereas the vacuum cookies are soft and creamy. The underside looks a little caramelized from the sugar, just as it says in the book. The restaurant staff like the cookies but are divided in their opinion as to which batch tastes best. 'Sorry but I think the normal cookies are the tastiest', says one of the testers. Most of the others agree with her. 

The crunchiest chicken thigh
We go in search of the secret of crunchiness. The first step is to coat the chicken thigh in flour. We also make a batter in which we will dip the meat before deep-frying it. Roy Burgman, the cook at the Restaurant of the Future, looks worried as we get ready to throw the chicken in the fat. 'Can I help, perhaps?'
The secret to this crunchy chicken thigh lies in the light batter. The idea is that this should be a crackly coating full of air bubbles and to achieve this mineral water is added with carbon dioxide bubbles serving as so-called nucleation sites. Bigger air bubbles grow from these sites by absorbing CO2 gas produced by the baking powder during the frying process. Crispy sounds have a positive effect on the eating experience, a subject the book dedicates a lot of space to. For instance, how do you measure crispiness in the lab and what is the difference between crunchy and crispy?
But we have other things to worry about as we are unable to follow the recipe to the letter. The frying temperature is supposed to be 200 degrees but the appliance only goes up to 190. This gives a crispy layer but without the golden colour. Our testers do like the taste of the end result but the batter is rather too run-of-the-mill for a super-crunchy chicken.

A savoury ice cream
The most exotic recipe on our list is tzatziki ice cream. We shred a cucumber in a blender and add half a litre of Greek yoghurt, gelatine, garlic and fifty grams of sugar. Then the mixture is poured into a common or garden ice-cream maker. We have to add 15 grams of salt, which we find rather strange. That seems pretty unhealthy but the essay explains that salt has an important function.
Ice cream consists of three phases: frozen water, air bubbles stabilized by fat or proteins and a matrix holding it all in place. This matrix consists of water that remains unfrozen thanks to compounds added to lower the freezing point. Usually that is sugar but salt and alcohol can also function as antifreeze. Salt is used here (with some sugar) as we are making a savoury ice cream.
The first bite from our tzatziki ice cream is a strange sensation. The ice cream looks good, smells of tzatziki but tastes incredibly salty while you are unconsciously expecting a sweet flavour. In the end most of it is left uneaten.
Elke Scholten is an assistant professor in Van der Linden's group and the author of the essay. When asked, she admits 'We didn't really perfect the recipe.' Scholten and her Advanced molecular gastronomy students are currently experimenting mostly with alcohol-based ice cream.

Insight
Dishes like the tzatziki ice cream show what is possible if you understand how foods function at the micro-level. This also encourages creativity. If you understand the basic principles of making ice cream, what is to stop you making a basil-and-tomato ice cream? But not all recipes are suitable for making at home as they often require specialist equipment such as precision thermometers and dry ice.
The real appeal of the book lies in the insights it gives. You finally understand why you get froth on your coffee and why you can never pour out the last drop of ketchup. And of course if your dish doesn't quite succeed, that is an excellent excuse to eat out instead.

With thanks to Nicolette Meerstadt and Karin Fikkers.

The kitchen as laboratory: reflections on the science of food and cooking, editors: C├ęsar Vega, Job Ubbink and Erik van der Linden, Colombia University Press, 22 euros, hardcover 312 pages

Re:act