Food and kitchens can seem resistant to innovation. Food is a basic substance, and much of what we eat has changed little in centuries.
Food preparation processes have changed much more rapidly. We can now keep food for longer, distribute it more widely, and make it more (or less) nutritious. Pit ovens and spit-roasting have come and gone; open fires became enclosed ovens and then induction hobs.
New food preparation innovations often start as weird inventions, then become industrial units, before becoming expensive must-have home gadgets, and then (for the lucky few) becoming mainstream. Microwave ovens, which made their first appearance in domestic kitchens in the late sixties are now owned by more than 90% of UK households.
Sous-vide is a phrase you may have seen on a restaurant menu, or heard on Masterchef. It means cooking vacuum-sealed food at precise temperatures in a water bath, often for many hours. It combines an industrial process for storing food for longer - the vacuum sealed package - with a much older observation about the benefits of long, slow cooking.
Over the years sous-vide technology has crossed from the domestic to commercial to restaurant kitchens and back several times, and we may now be on the verge of its appearance in domestic kitchens again. Whether it crosses over to become an essential part of the kitchen remains to be seen. The story of the invention and re-invention of sous-vide cookery illustrates some of the ways in which food process innovations are propagated.
The scientist credited with the origins of sous-vide cookery is Count Rumford, an eighteenth century scientist who conducted many experiments on heat, and made interesting observations about cooking along the way. His essays convey personal interest and curiosity with an experimental mindset in search of evidence. He was very concerned with the fuel wasted by rapidly boiling meat when it could be cooked at lower temperatures. In one accidental experiment, he left a shoulder of mutton in a low-temperature oven overnight:
'Desirous of finding out whether it would be possible to roast meat in a machine I had contrived for drying potatoes, and fitted up in the kitchen of the House of Industry at Munich, I put a shoulder of mutton into it, and after attending to the experiment three hours, and finding it showed no signs of being done, I concluded that the heat was not sufficiently intense; and, despairing of success, I went home rather out of humour at my ill success, and abandoned my shoulder of mutton to the cook-maids.
It being late in the evening, and the cook-maids thinking, perhaps, that the meat would be as safe in the drying-machine as anywhere else, left it there all night. When they came in the morning to take it away, intending to cook it for their dinner, they were much surprised to find it already cooked, and not merely eatable, but perfectly done, and most singularly well-tasted.'
In the mid-sixties, Cryovac created a vacuum sealing process using food and heat-safe plastic films to extend the shelf life of foods. These foods were then 'boiled in the bag' to heat them. However, in 1974, two parallel discoveries suggested that vacuum sealed food could be cooked at much lower temperatures, to replicate the 'singularly well-tasted' effects of Count Rumford's experiment.
Pierre Troisgros, of the three Michelin-starred Restaurant Troisgros in Roanne, was looking for a better method of cooking foie gras without the expensive loss of fat from sauteing. He collaborated with fellow chef Georges Pralus and they discovered that wrapping the liver in layers of plastic could reduce the weight loss to less than 5%, compared with more than 20% with the previous method.
At the same time, scientist Bruno Goussault was developing industrial processes for longer-life meals, demonstrating a 60 day shelf life for a sous-vide beef stew, for instance. So from its inception, sous-vide has had a dual life as an industrial method for increasing shelf life, as well as a tool for high-end restaurants to make better food. Both saw the value in preparing food in advance, and then heating it consistently to a precise temperature.
The stability of sous-vide prepared meals have made it popular with train and airline caterers, as well as chain restaurants; Joel Robuchon collaborated with Goussault to create a first class menu for SNCF in the eighties. In this context, few restaurants or caterers are keen to advertise the fact that the food is prepared offsite and reheated to order. The stigma of 'boil in the bag' still suggests this method is inferior to fresh food, prepared on site. In 2009, Gordon Ramsay was subject to a 'scandal' when The Sun found his gastro-pubs serving meals that were prepared off-site in an industrial kitchen, and reheated. Consumers are still reluctant to believe that such plastic packaged food can also be of high quality.
However, sous-vide has another life as an essential tool of modernist cuisine, and is found in elite restaurants such as The French Laundry and El Bulli. Here, while they also prepare food ahead, and appreciate the great consistency of sous-vide, they are more likely to experiment with other effects of the technique. Compressing the food with the vacuum seal can create novel textures in pineapple, melons and celery. The vacuum also helps infuse flavours into the food, so adding herbs, spices or truffles can penetrate the food more thoroughly. Cooking vegetables sous-vide prevents any flavour or nutrients being lost to the cooking water, concentrating flavours. Meat cooked this way can be made perfectly rare throughout, without the gradation that comes from grilling.
These attributes, especially the ability to cook meat to a perfect doneness, have interested enthusiastic home cooks. Sous-vide has started to become a usable technology for domestic cooks, with a few companies producing kits suitable for home use, but it is yet to find an audience beyond a few food enthusiasts. As the NY Times describes it, 'The heavy, boxy countertop unit and the long cooking times of some sous-vide recipes (up to two days) are not always inviting.'
More practical home models are appearing, though. Sous vide at home startup Nomiku has already raised $750k for their second generation sous vide circulator on Kickstarter, due to ship this year. Similar models, which can be used with an ordinary saucepan, are already available. Some have even experimented with using a Raspberry Pi as a sous-vide controller.
It has now moved into supermarkets as well, with ready-to-cook meals such as lamb shanks, or barbeque pork being sold 'pre-cooked in the pouch' (although they seldom use the phrase 'sous-vide'). And it remains popular with catering companies, as the vacuum seal means that food can last for days or weeks once cooked, before being reheated. There is a new restaurant chain, Suchef, trying to sell diners on the benefits of sous-vide food ('improved nutrition!, less additives') in that hotbed of culinary innovation, East London (also home to the Cereal Cafe and the Porridge Cafe).
Whether sous-vide starts to be seen as a home kitchen essential will depend on improvements in the equipment, making it cheaper and smaller. It will also need to find the right offer to make to the home cook. It can offer lower energy cooking, and better retains nutrients, especially for vegetables. However, it generates no smell of cooking, and provides very little opportunity to intervene - checking the food part-way through would break the seal. So it can seem off-putting to those used to hands-on cooking. Perhaps its best bet, like the microwave, is in the development of a parallel industry of pre-prepared meals that can be heated at home.