After my recent Spheres and Circles dinner adventure I decide to put together a quick post on how to get started with frozen reverse spherification.
The basic recipe for reverse spherification is really quite simple. First create your flavourful liquid that you want to spherify and add 2% calcium lactate to the mix. Next freeze the liquid in a mould to create frozen spheres. While the spheres are freezing, prepare a 0.5% solution of sodium alginate dissolved in distilled water (5g sodium alginate in 1000g of water). Let the alginate sit for at least 2 hours to fully hydrate and also lose any bubbles that were created while mixing. I prefer leaving mine overnight in the fridge which matches well with the time it takes to freeze.
The spheres are created by dropping the frozen ice into a warm alginate bath for a ~20 seconds during which the calcium ions in the frozen liquid interact with the alginate bath to create gel skin that encapsulates the spheres. Gently stir the bath without touching the sphere for best results.
Finish up by fishing the sphere out of the alginate bath using a slotted spoon and then stir it in two separate rinsing baths of water to remove any traces of the alginate and place it a holding bath of either oil or the flavourful liquid till you are ready to serve.
Ingredients and equipment
While I started out with a kit from Molecule-R, I feel that if you primarily want to do spherification you are better off buying the following ingredients in bulk. The biggest issue in the kit is that the chemicals come in a limited number of specific sachet sizes which makes it hard to scale your own recipes correctly. Most of the following links are to Modernist Pantry but this should all be available on Amazon as well. The following is what I would recommend as a starter set:
- Calcium Lactate is the source of the calcium ions that you must add to your flavourful liquid. You can also use Calcium Lactate Gluconate which is supposed to be even more flavour neutral but at this point I havent run into any taste issues with straight calcium lactate.
- Sodium Alginate is a seaweed extract that serves as a cold gelling agent and creates the sphere boundary layer.
- Distilled water is the safest way to hydrate the alginate as tap water may contain calcium ions that will cause the alginate to gel prematurely.
- Slotted Spoons are necessary to move you spheres around without contaminating the various baths. They are useful both for making caviar and for the larger spheres I am talking about here. This one is perfectly functional but personally I would get the much sexier Ferran Adria version.
- Digital scales are probably the most important tools you need to do the spherification. You will generally need one to measure larger quantities for the base liquids and another one with 0.1g precision to measure the chemicals. I have been using the linked ones at home with good results.
- An Ice mould/tray is needed to freeze the liquid before you can make the spheres. You do not need the fancy molecular moulds that are sold at the modernist websites. While the fancy ones are definitely easier to remove ice from, I have been using a standard circular ice tray with great results. You should make sure that it is the right size for the sphere you want. The kit mold I got is ~5-7ml in volume while the standard cube is ~10ml in size which makes for a more substantial sphere which I definitely prefer.
- Xantham gum (optional) is a thickening agent for when you want to play with the texture of the fluid in the sphere. I would recommend getting comfortable with basic spherification first before using xantham and other gums to adjust mouthfeel.
- Amuse Bouche spoons (optional) are the most common way of serving spheres. That said you can also serve them in regular soup spoons, shot glasses, etc…
Tips and Tricks
I have now done this several times and have created spheres of a wide range of things from mojitos and bloody marys all the way to yogurt and mango puree. The following are some tips and tricks that may help you get you spheres done better/faster
- Mix the lactate using an immersion blender – leads to a very fast and even mix. It does however create a lot of bubble and you want to let the liquid rest in the fridge for a while to lose the bubles before pouring in the mould. You can mix with a spoon as well but I find that the last bits of the lactate dont always dissolve and I sometimes have to strain the mix to remove them.
- Watch the texture of the liquid before you freeze it. Liquids with a thicker consistency (mango puree, yogurt, bloody mary mix) have a better mouthfeel when they burst. That said there are certain liquids that work better are regular fluids due to the original expectations (eg: pani for pani puri). You can use xantham gum (say ~0.5%) to slightly thicken the liquid but be careful with bubbles as the thickened liquid will not lose them easily.
- For encapsulating spheres (eg: spherified mojito with an encapsulated min leaf below) take care that the encapsulated item is entirely enclosed in the ice. If any part of it sticks out of the ice it will cause the alginate skin to rupture. I recommend using 2 step freezing where you first fill the mould half way and drop the floating substance in the mould and wait for it to freeze completely before adding a second layer of liquid on top to guarantee encapsulation. In the case of a heavy substance that sinks you will want to add the item while making the second layer.
- You do not have to store frozen spheres in the mould. When I am making several different kinds of spheres I freeze each liquid overnight, pop it out of the mould and store them in a closed container in the freezer. This is particularly useful when you have limited moulds and lots of spheres to make.
- Do the spherification well before the meal. Sometimes you run into issues during spherification or may have yield issues so I suggest doing the alginate bath step several hours before the meal itself. Doing it just before guests arrive adds more pressure to the meal than I would like.
- Use a warm alginate bath for fast spherification. If you warm the bath to ~50C it helps the sphere to melt faster and form the skin quicker.
- I find that using a saucepan with non vertical edges makes it easier to pull the spheres out with the slotted spoon. I get more breakage when I use a saucepan with vertical walls.
- Experiment with how long you want the keep the sphere in the alginate bath. The longer it stays the thicker the skin will be. You generally want as thin a skin as possible especially for non-viscous liquids. Having the bath set to a specific temperature will help you improve the repeatability of the spherification. I generally use 20 sec per sphere in a 60C bath.
- Leave the frozen spheres in the freezer for as long as possible. I prefer pulling them out 2-3 at a time so that they are still solid when I drop them in the bath. If they start melting before the bath they end up leaking liquid into the bath which can break the spheres.
- Wipe your spoon with a dry paper towel every time you dip it in the alginate bath. This prevents any contamination from the holding bath. Wipe the bottom of the slotted spoon with a paper towel to absorb excess water before adding the holding bath – this is particularly important if you are using oil to hold the spheres.
- Wait at least 10 min after the spherification bath to let the core of the sphere melt before serving.
- Keep checking the alginate bath for any gel floating in the mixture. This is particularly important if you have been having yield issues as the ruptures spheres leave a lot of gel reside that affect future spheres being made. Luckily the slotted spoon is usually sufficient to fix the gel out
- If you are making a large number of spheres (say 20+) you probably want to make excess alginate and use it in batches rather than topping up the same bath. This will help reduce any issues from free floating gel in the bath. Plus if you have excess alginate you can always store it in the fridge for later use.
- You can store the completed spheres in a bath of olive oil for several days but then you end up having to thrown the oil away as you cant really reuse it. Instead I prefer storing the spheres in a batch of the flavourful liquid itself as you can always drink the liquid after service.
- While amuse bouche spoons are the most common serving methond for spheres, you should feel free to play around with different things. I have served them in shot glasses (with and without other liquids), on a wafer, suspended in alcohol, directly in the holding bath, etc… Sperification is all about experimentation and that should extend to the plating as well
- Consider using lab beakers to measure and mix the ingredients. They are cheap, oven safe, microwaveable, easy to clean and allow you to inspect the bottom to check if the chemicals have dissolved completely. They are also super easy to pour from – I usually use a 100ml beaker to fill the moulds as it gives me good control and allows me to measure the amount poured.
- Play with the serving temperature of the spheres by adjusting the holding bath temperature. For higher temperatures you can heat the bath before adding the spheres while for lower temps just refrigerate the spheres in the bath. If you do heat the spheres please warn the guest before they eat them as you dont want anyone to burn their mouth with something that is too hot.
- Try serving your spheres with other interesting accompaniments. Common ways to punch up the flavour and texture are to drizzle olive oil, shave cheese over the top, plate on a crunchy bed, top with sauces, sprinkle salt/spices, etc… For example the pani puri spheres below have been topped with a sweet tamarind sauce and served with a fried chickpea balls to replicate the crunch of a puri breaking.
Hope you folks liked my guide to frozen reverse spherification. As you can see it is a very simple technique that can easily be done at home. It does takes some time but most of that is in prep work to be done before the meal. You can also pre-make the spheres a day or two before the meal and store them in the holding bath till you are ready to serve.
The following are some of the spheres I have made with this exact same process and should be straightforward to repeat:
- beet juice
- mango puree
- bloody mary (alcohol)
- bloody may mix (no alcohol)
- orange juice
- grapefruit juice
- mojito (alcohol)
- pani (spicy liquid for pani puri)
Thanks for reading and go try out some interesting spheres of your own.