What is ‘sous vide’?
Sous vide literally translates to ‘under vacuum’. It’s an increasingly popular way of cooking food, especially meat, by sealing it in a food-grade pouch and then putting it in a precisely-controlled water bath – usually at a low temperature, for anywhere from 5 minutes to 72 hours.
So it’s like poaching?
No, not really. The food is cooked in hot water. But the difference is that it’s encased in a vacuum-sealed bag which stops the juices from seeping out and being diluted by the surrounding liquid. If you poach a piece of chicken or boil vegetables, then some of the food's flavour is lost to the water it's cooked in. But by cooking inside a sous vide vacuum bag, these juices aren't lost, and the flavours are more concentrated. The other big difference is the precision with which you can control the water temperature. When you’re poaching food, the two options are generally ‘boil’ or ‘simmer’. But, with sous vide, the water temperature can be controlled down to 0.1 degree. This means you can cook meat or fish at the exact temperature which will keep it naturally moist and juicy.
Will the meat have that horrible poached look?
You’re right to be concerned. Poaching food isn’t aesthetically great, and the meat won’t look its best straight after it has been taken out of the water bath. Nor will it taste at its best – the Maillard Reaction happens when pan-fried meat is browned, and it’s a big part of the meat-flavour. So when the meat has finished being sous vided, heat a little butter or oil in a pan, and very quickly sear the outside. For smaller pieces of meat or fish, a wide-flamed blowtorch is another effective way of browning. But be sure to use a chef's blowtorch rather than a cheap, crème brulee torch, which won’t be much use on a joint of meat
What about the gravy...?
Don’t worry – the meat still gives out juices. In fact, the juices collected in the bag are even better than roasting tin juices, because they can't evaporate away.
But why does the food have to be cooked in a special vacuum-seal packet to catch the juices - surely any bag will do?
Well, water conducts heat 23 times better than air. Heston Blumenthal illustrates this by saying that “you can put your hand in a 100°C oven for a few seconds without coming to harm, but you wouldn't even think of doing the same thing with a pan of boiling water”. So by removing any air from the bag, the heat conducted by the water moves straight to the food, cooking it evenly and precisely. Aside from anything else, it’s unwise to use any old plastic bag to cook food in at a high temperature. All the bags sold in the sous vide section of the site are food-safe, and specifically designed to be used in hot water.
What’s wrong with a good old oven?
We’re not suggesting that you rip out your oven and replace it with a sous vide machine. There are lots of emotional articles about home cooks struggling to make scrambled eggs in a sous vide machine, with sad families waiting half an hour for their breakfast. Really, just make scrambled eggs on a hob. It’s quicker and easier. Sous vide machines come into their own when slow cooking pieces of tough meat and cooking several perfect steaks at once. The sous vide technique is very forgiving with cooking times, as they allow far more leeway than ovens which can quickly dry-out and overcook meat. So with sous vide, you can do all the prep for a dinner party hours in advance, and spend very little time in the kitchen when guests arrive. Plus there's a lot less washing up.
I still don’t understand why floating meat in water makes it taste so much better.
Ok then, here’s the science part. When you cook meat in an oven, the aim is to heat the centre to around 55°C – enough to kill off pathogens like salmonella and E.Coli, which generally can’t grow much above 50°C. So for argument's sake, let’s say that you’re cooking a thick cut piece of steak with normal home kitchen apparatus, there are two conventional methods: either searing both sides in a hot pan around 250°C, leaving it to rest and hoping that the centre comes up to 55°C. Or searing one side of a piece of meat in a pan, then putting it in the oven at around 135°C and hoping that you manage to take it out when the centre reaches 55°C. Heston Blumenthal describes both these options as a culinary equivalent of “using a flamethrower to light a cigar”. The likelihood is that while trying to bring the centre of the meat up to 55°C, the outside will become dry and overcooked. Sous vide cooking is quite different in that it slowly heats up the entire piece of meat to 55°C without overexposing the outer layers to an unnecessary blast of heat.
Is it good for cuts other than steaks?
Sous vide steaks get a lot of air time. But sous vide cooking cheap cuts of meat can be even more effective. The parts of the animal which get most exercise – like shoulders and legs – contain more collagen. This is made up of three molecules tightly twisted together like a rope, and make the meat tough to chew and cut. But between 50°C to 55°C the collagen dissolves and turns into gelatin. This is traditionally done through braising or stewing, but sous vide cooking is a great way to get the best out of large, tough cuts of meat and turn them into something a little bit special.
Can you put seasonings into the bag too?
Absolutely. Seasonings often intensify during sous vide cooking, which is an added bonus... most of the time. A sliver of lemon in with a chicken breast infuses wonderful flavours. Even just a bay leaf or a couple of peppercorns impart intensified flavours. There are a few rules worth sticking to though. 1. Raw garlic flavours don’t always improve in a sous vide scenario, so use powdered garlic – and even then, only use a tiny pinch. 2. If you’re using a wine marinade, cook it in a pan first, otherwise the heat inside the water bath will cause some of it to turn from liquid into vapour, which result in the meat cooking unevenly. 3. Use processed oils instead of extra virgin olive oil, which can develop metallic tastes during sous vide cooking. For olive oil flavours, use a drizzle as a finishing oil after cooking, not during. 4. Avoid using traditional stock-vegetables to flavour meat. Often the water temperature won’t be high enough to soften carrots, onion and celery. Perhaps include them very finely sliced in a salt-brine before you cook the piece of meat. This helps to flavour and tenderise. 5. Be careful using marinades and sauces which will acidify sous vide meat as this will affect the cooking times. That's not to say that you shouldn't use fruit juices, wines or vinegars - just make sure that you do your research first.
Sure, it’s not cheap. But with new sous vide equipment designed specifically for home use coming onto the market, more and more machines are popping up in domestic use. A whole home sous vide kit (including sous vide machine, vacuum sealer and vacuum bags) costs £350-£450. But if you think that a sous vide can turn brisket (£15/kg) into fillet (£50/kg), then there’s a strong argument that the investment is priceless. Click to see our full sous vide range, including the SousVide Supreme, vacuum sealers, and sous vide bags or pouches. Do you have any more questions? Please ask them below!