LAB TECHNIQUES FOR THE KITCHEN
Wouldn’t it be nice to create some fancy Michelin Star food at home? Food Guru Natasha dons her chef’s whites and plays with some whizzy kit. Recipes included! Watch out Heston Blumenthal.
Molecular gastronomy is now well known and used by chefs, whether in fine dining restaurants or quaint little bistros. It has even started to creep into our kitchens. The art of mixing science and food is on everyone’s lips: whether it’s trying out a new technique at home or indulging in experimental dining, we all want a taste of the action. Where do these intriguing techniques come from – and where is molecular-cuisine heading? As a food-lover and scientist, I divulge how specialised techniques have gone from the lab to kitchen. White coats are essential in both…
Starter: The spin-y machine soup
The most dangerous addition to the kitchen is what we scientists call a table-top centrifuge. Designed to spin at huge speeds, sometimes generating up to 13,000 times the force of gravity, it allows us geeks to separate a liquid into its different parts based on weight. For example, freshly squeezed orange juice contains sugary water and fruit bits. After spinning, heavier parts will be found at the bottom of the tube, the ‘pellet’, whilst lighter parts will remain in the top layer, the ‘supernatant’. This method is used every day around the world, for instance to isolate blood cells from whole blood and extract protein from bacteria. With an eye for advancing the cooking process, experimental chefs have seized upon this super-spin machine – to clarify a juice or broth, for example. As food fashion leans towards the refined, light and fragrant tastes often found in Asian cuisine, a centrifuge could separate out the cloudy and messy parts of a stock, while retaining those beautiful infused flavours.
WARNING: I will not be providing a do-it-yourself recipe to go with this up-andcoming technique because centrifuges can be extremely dangerous. When spinning at such high speeds around their central rotor, centrifuges create huge amounts of force that, if unbalanced, can lead to devastating results (think ‘bye-bye kitchen’). A rule of utmost importance in the lab is that a centrifuge needs to be perfectly balanced. Tubes of fluid must be placed symmetrically within the circular spinning bowl: if you place one tube containing 50ml in the centrifuge, you must place another tube of exactly equal volume (e.g. 50ml of water) on the opposite side. If you don’t, you are likely to end up with a shattered machine – or worse: super high-speed centrifuges have been known to crash through walls and ceilings. You have been warned!
Main Course: Modern day boil-ina-bag
Sous-vide cooking means ‘ under vacuum’ in French. The idea behind this method is to cook food (meat in particular) at a tightly regulated temperature. So if you’re keen on that perfectly medium-rare steak or tender and moist chicken, this is the one for you. A wide range of machines and bags are available for cooking sous-vide. However, cheaper solutions are also available to achieve the same temperature control: you can get similar results with a sealed jar or oven bag and a modern oven or water bath whose temperature you can control to one or two degrees. There are many benefits to cooking sous-vide. Firstly, cooking at such precise temperatures means a minute or two of over-cooking will not ruin your food – a perfect stress-beater when cooking steaks at a dinner party. Secondly, the controlled temperature means food is cooked very evenly – of particular importance when cooking chicken or pork, when it is notoriously difficult to get the balance of perfectly moist but not undercooked white meat. The meat is also cooked very evenly. This is because the vacuum-sealed meat is surrounded by the hot water from all sides. Another advantage to this method is that it’s completely consistent – once
you’ve worked out your times and temperatures, you’ll get a perfectly juicy steak every time. Best of all, cooking within a vacuum seals in all of the vapours around the meat during cooking, giving you dishes that are always tasty, juicy and tender. Check out the recommended link below for recipes to try.
Accompaniment: Beautiful food bubbles
Spherification is a less stressful technique that doesn’t require actual cooking; it is sometimes also referred to as ‘making caviar’. The process involves making little gelatinous spheres from a liquid preparation. Discovered by Unilever in the 1950s, the technique started to hit the big time in Ferran Adria’s renowned molecular gastronomy restaurant elBulli in Spain. Adding a layer of texture and intrigue (and, of course, artistic plate setting), these little beads are still all the rage in fine dining. Two main methods are used by chefs to create beautiful little spheres; the choice depends on the calcium content of the liquid. Here comes the chemistry: if the liquid contains no calcium, it is mixed with sodium alginate, a gum-like substance extracted from brown seaweed, and then dripped drop-by-drop into calcium chloride or calcium carbonate. This technique is called Basic Spherification and has both pros and cons. On the plus side, it creates spheres with a very thin outer layer so that they dissolve beautifully in the mouth. However, the jellification process doesn’t stop when the spheres are removed from the calcium bath and washed, so they need to be sent out of the kitchen pronto if you don’t want your guests to be chewing on a gobstopper. An alternative technique, used for liquids containing calcium or with a high acid or alcohol
content, is called Reverse Spherification. The liquid is first mixed with the calcium chloride and then dropped into an alginate bath. The calcium chloride causes the alginate protein strands to become cross-linked, forming a gel. Making the bead depends on how you drop this gel into the alginate water: a larger drop will create a large sphere; a small drop, a dainty little bead. It goes without saying that some dexterity is required for this one! This method gives the food blob a thicker membrane, but you are able to make beads from most any liquid and the jellification process is stopped by rinsing the beads in water.
Ready to try it out? Direct from the elBulli kitchen, this Mozzarella bead recipe is delectable (kindly provided by Molecular Recipes): For the Mozzarella mix, you will need 220 g Buffalo Mozzarella 150 g Mozzarella whey 70 g double cream 4 g salt For the Alginate bath 1.5 litre water 7.5 g sodium alginate Your first step is to prepare the alginate bath. Mix the sodium alginate with the water using a blender until the alginate is completely dissolved. Bear in mind this might take some time. Leave it in the fridge for 24 hours. For the mozzarella balls, shred the mozzarella and blend together with the whey in a blender until you obtain a grainy solution. Boil the cream and add it to the mozzarella mix and blend for another 10 seconds. Now add the salt and mix. To make your spheres, remove the alginate bath from the fridge and prepare the mozzarella mix in your preferred spherification tool (whether it’s a special spoon, syringe or pipette – see our top tips on spherification below). Carefully drop the mix into the bath, making sure the beads don’t touch so that they don’t stick together. Leave the balls in the bath for about 12 minutes
and remove with a slotted spoon. Rinse with water and strain them carefully. Serve immediately with tomatoes, basil, olive oil and a generous grinding of pepper. Or you could store it in a plastic box in the fridge for later. If you’re feeling ambitious and want to try your hand at a basic spherification recipe, this recipe will give red wine a complete change in texture and taste! For the sodium alginate bath, you will need 3 g sodium alginate 325 ml water For the calcium chloride bath 5 g calcium chloride 1 litre water For the spheres, use around 200 ml of a liquid of your choice, be it wine, soy sauce or anything else that titivates your taste buds. The first step is to dissolve the sodium alginate into water until you have a powdery solution (an immersion blender is good for this). Bring the solution to the boil and then let it cool at room temperature. Next prepare the calcium chloride bath simply by dissolving the calcium chloride in the water. Now mix your chosen liquid with the sodium alginate solution at a 2:3 ratio of liquid to sodium alginate. Taking your favourite spherification tool, gently drop the liquid into the calcium chloride bath and let the beads ‘cook’ for a minute before removing them with a slotted spoon, rinsing them in water and draining.
Remember to serve these immediately!
Dessert: Dry ice surprise
Using dry-ice and liquid nitrogen in cocktails has become quite popular of late, with the layers of smoke adding a certain mystique. But being so near liquid nitrogen can be dangerous.
Liquid nitrogen’s main purpose is for rapid freezing: it is used to freeze samples of tissue and for storing sperm and eggs. It is also often used for cooling computers in certain settings. With a temperature of -196°C (or less), dropping an object into liquid nitrogen has the effect of freezing it instantly. Liquid nitrogen piqued the interest of forwardthinking chefs in the search for the perfect ice cream. When making ice cream, the liquid must be frozen slowly and regularly remixed during the freezing process to create an even texture. The longer the mix takes to freeze, the more ice crystals are formed and the ‘grittier’ the ice cream will be. Preparing ice cream in liquid nitrogen means a very fast freezing process – and very few ice crystals. This creates a much smoother and creamier ice cream – all for your delight.
WARNING: once again, this is not one to try at home! Liquid nitrogen is treacherous: liquid nitrogen evaporates very rapidly when poured (this is what also makes the exciting smoke) – but it expands so rapidly that one litre of the solution can create up to 700 litres of gas. This could deplete the level of oxygen in a room very quickly – with potentially fatal results. Most labs will keep their stock in insulated containers stored in rooms with specialised ventilation and alarms in case of a spill. But if you happen to be trained and have regulated access to liquid nitrogen (or know someone who does), why not try this gorgeous ‘Berrylicious’ ice cream recipe in between some centrifuge experiments! You will need: 5 or more litres of liquid nitrogen Gloves and goggles A plastic or stainless steel salad bowl 950ml whipping cream 425ml ‘Half and Half’( half light cream and half milk) 350g sugar 500g of mashed mixed berries 2 teaspoons of vanilla extract Mix the whipping cream, the ‘half and half’ and the sugar using a wire whisk until the sugar has dissolved. Put your gloves and goggles on and pour a small amount of liquid nitrogen into the bowl containing the mixed cream and sugar. Continue to stir while adding more liquid nitrogen slowly. As soon as the base starts to thicken, add the mashed berries and stir vigorously. When the ice cream becomes too thick for the whisk, use a wooden spoon. Once it becomes too hard, remove the spoon and simply pour the remaining liquid nitrogen on to the ice cream. Wait for all the liquid nitrogen to boil off before serving.
For everything and anything you may need to become the best molecular gastronomy chef, check out the Molecular Recipes store online! They also have lots of handy information: 10 tips to create a perfect sphere
An introduction to sous vide cooking Sous-vide supreme has some great sugges
tions for the perfect sous-vide cooking times!
A video showing the ‘ secret to ultrasmooth Ice Cream’ with liquid nitrogen
ABOVE: Green tea after tKe VSKerLfiFatLRn process.
BELOW: Image courtesy of
Tiny Urban Kitchen.
Natasha Agabalyan is on her way to becoming a Doctor of Cell Biology in Brighton, UK. In between drinking far too much coffee and blogging at The Science Informant, she has a love of finding out interesting tit-bits from all aspects of life. You can follow her on twitter at @SciencInformant.