Science in the Kitchen

One day, a few years ago, I was sitting my office at Bristol University when the phone rang and a very enthusiastic voice asked "why should I add salt to the water when I cook green vegetables?" This happens to be one of my pet topics; the answer of course is that there is no really good reason, except tradition (see the article on kitchen myths to find out why). So of course, I was happy to spend some time answering the caller.

It quickly turned out this was no casual enquiry - the caller was none other than Heston Blumenthal - one of the UK's top chefs. As we talked on the phone it soon became apparent that we shared a common philosophy that the application of science to cooking can only improve our techniques and experiences. Thus we started working together. Heston and I meet every few weeks to talk about the science of food and cooking - usually the conversations start with some specific issue. Maybe one of Heston's chefs has noticed something odd in the kitchen, maybe I've read about some new and interesting scientific discovery, maybe there has been some problem in the kitchen and Heston wants to ensure that in future the problem is solved.

But always, we end up talking about many other issues sparking off new ideas for cooking processes and dishes, etc. Obviously, much of this comes to nothing, but a few ideas lead to real novel developments. Our collaboration has been very fruitful and influential. Heston is widely recognised as one of the UK's top chefs so his interest in applying science in all his cooking has given Molecular Gastronomy credibility in the catering industry. Perhaps the most important aspects of our collaborations are the development of new cooking methods and the use of scientific equipment in the kitchen which have led to the appearance of completely new dishes on his menu.

One of the most dramatic examples relates to the way in which meats are cooked at the Fat Duck. These days most meat and fish are cooked at low temperatures for long times using temperature controlled water baths. This allows the restaurant to serve wonderfully tender and pink meats in a totally consistent fashion. The problem with traditional methods has been that meats were cooked by exposing the outside to a high temperature (in a pan or oven) and then letting the heat diffuse inside until the temperature at the centre is just right. If the temperature is too high the meat proteins contract and expel water making the meat tough and start to go grey, rather than pink. If the temperature is not high enough the meat seems raw. The ideal temperature varies between meats, but is usually around 55 to 58°C; above 60°C the meat will soon lose moisture and become dry and tough; below 50°C it will still be very red and seem raw and cold. Normal cooking processes mean that if the centre is at the ideal temperature the outside is much hotter and thus tough.

However, at the restaurant now the meat is first vacuum sealed in a plastic bag (to prevent any oxidation of the meat surface and avoid any contact with the hot water). Then the bag is put in a temperature controlled water bath (a standard piece of laboratory equipment) with the water kept at the desired temperature want (say 58°C for lamb). The meat is then left in the bath for a long time (several hours) so that it reaches a uniform temperature throughout; it ends up as a perfectly cooked pink and tender piece of meat.

As well as the physical processes of food preparation, Molecular Gastronomy also involves understanding and controlling the processes involved in flavour release and perception. One of the most interesting aspects of recent research is that we are only just beginning to understand some of the complexities of how our brains interpret flavour (see the article on taste and flavour). For example, when an aroma has been present in our noses for a long time ( about five minutes) we tend to ignore it. So if we keep on eating the same food for a long time its flavour will pale and even disappear. Thus we need a variety of different tastes and flavours on a plate if we are to fully enjoy a good meal. Here the Eastern cuisine which offer many small courses and the Spanish tapas can point the way to better appreciation of our food.

At the Fat Duck, Heston has taken this on board both by ensuring that every dish has a variety of different and complementary flavours and textures and by offering small appetisers between courses, thus keeping the palette interested without ever switching off from a particular flavour. We don't know where our collaborations will lead us next, but we will continue to enjoy talking about food and experimenting with novel cooking techniques and producing new flavour and texture combinations. Hopefully some will end up on the menu at the Fat Duck soon and some will even reach the supermarkets in a few years time.

Peter Barham