MOLECULAR GASTRONOMY: What makes green beans get even greener as they cook? Why is vinegar useful when cooking shellfish? These are just some of the culinary questions to which scientists have found answers
DR JUAN VALVERDE admits he got a few funny looks when he went to put some green beans into an MRI machine, which is normally used to scan body parts. But it wasn’t as bizarre an investigation as it may seem. “You can tell a lot about the internal structure without needing to destroy the tissue,” explains Valverde, who was exploring the inner secrets of green beans for his PhD in Paris.
By looking at the internal structure of the vegetable in various states from raw to cooked, he could work out something that had long been a puzzle to cooks: why do green beans become even greener as they are cooking?
He found the answer. “There’s some air inside the green beans and when you cook them the air is released, and that changes the perception of the green colour,” explains Valverde.
He spent several years researching in the lab of Hervé This, who co-founded the field of molecular gastronomy with fellow scientist Nicholas Kurti.
“They thought that food science was too focused on what happens in the food industry, which is not exactly what happens in the kitchen,” says Valverde. Cooking in a pan is not the same as heating something in an autoclave, a vessel that is used in the laboratory for high temperatures.
“The difference between molecular gastronomy and food science is that molecular gastronomy has a real interest in what happens in a normal kitchen, which could be in a house or a restaurant,” he adds.
So after studying chemistry in his native Spain, Valverde found himself trying to unlock the secrets of how beans first green up and then fade over time as they are boiled.
“Tons of green beans are being cooked every year and yet no one knew why this happens,” he says. “How come we have the situation where we are cooking something every day and we don’t know what happens.
“Often the way we prepare something in the kitchen is based on an old wives’ tale, or because your mother used to tell you to do that, but more analytical and structured thinking can help foster culinary innovation. The main aim is to understand it in a scientific way.”
Valverde is network scientific officer of the Irish Phytochemical Food Network at Teagasc’s Ashtown Food Research Centre in Dublin. His research looks at the properties of chemical compounds in carrots, broccoli and onions.
He has a particular interest in glucosinolates, naturally occurring plant compounds that may have health-related properties, but which can impart characteristic tastes too.
After we take a walk through the new facility in Ashtown, which is definitely more of a laboratory than a kitchen, Valverde explains the value of characterising these chemical properties, likening the process to how Dmitri Mendeleev set out the periodic table of the elements in the 19th century.
“By studying the general properties of elements and classifying them, he made a map of elements, and he could predict the properties of elements that hadn’t been discovered yet,” he says.
“I think classification and understanding how things work lets you find knowledge gaps and, at the end of the day, you are going to tap them. Where you see a gap, you have an opportunity to improve and innovate.”
Valverde lectures students at the Dublin Institute of Technology on culinary science, and he describes how they are encouraged to think analytically about the properties of foods and processes. By applying scientific thinking about the properties of ingredients, they can get a new perspective even on relatively basic practices, such as like making emulsions, stocks and sauces, he explains.
“If you are doing an emulsion, you need three compounds: a water solution, a fat solution and something to mix them together,” he says. “So you can do up a table and you can try different kinds of oils – olive oil, grapefruit, butter – then different types of water solution, and different types of mixer.”
Other examples might include using the acidic properties of vinegar to degrade crustacean shells when making stock, or changing the order of adding ingredients in a recipe to protect certain flavours.
In molecular gastronomy, the route from the successful experiment to the consumer can be a quick one, he notes.
“The great thing in molecular gastronomy is that the applications, in 90 per cent of cases, are more transferable than in food science. In food science you need an autoclave and to do things on an industrial dimension. But it’s great to understand scientific concepts from cooking because you can just do it in a pan.”
So how do you move discoveries out of the laboratory and into the kitchen? Through scientific papers, conferences, books and by working with chefs themselves, according to Valverde, though he says there can be hurdles.
“The biggest barrier is language: chefs have one type of language and scientists have another,” he says. “And you need a couple of weeks for each to understand what the other is saying.”
Molecular gastronomy can have an economic impact by enticing consumers, including tourists, to areas where chefs base their restaurants, says Valverde.
He describes how Spain has put itself on the map in recent years through culinary innovation, not to mention the success of British chefs such as Heston Blumenthal.
Ireland needs to organise its resources and initiatives, he notes. “We have fantastic products, and it’s working pretty well, but we need to bring more people in and to make a more consolidated culture,” he says.
Valverde hopes the work will inspire students to think this way about food and to innovate, he says. “Sometimes it’s easier to work with people who are studying now, the chefs of tomorrow,” he says.
“The seed is being planted and carefully watered. So hopefully it will be germinating in the next couple of years.”
