Part 1: Spherification
Spherification is a technique that uses a calcium salt and sodium alginate to form a small, gelatinous membrane around a liquid ingredient. When the membrane is pierced, the liquid flows out. Probably the most famous form of this technique is the formation of caviar with these liquids; essentially making small pearls not unlike the tapioca balls in bubble tea, but made from juice, alcohol or other liquids.
What you'll need:
- Calcium salts*
- Sodium Alginate
- Distilled water**
- A small slotted spoon
- A blender (immersion or otherwise)
- A scale that measures at least tenths of grams***
- (Optionally) a hemisphere silicone mold.
*
Your options for calcium salts are calcium chloride, calcium lactate, or calcium lactate gluconate. Depending on the salt you use, you need a different amount and/or technique. Calcium lactate glutonate is considered the best because it has a neutral flavor.
** Most tap water, especially 'hard' water, naturally contains varying amounts of calcium. Making an alginate bath with said calcium-containing water would start the gelling process before you even have a chance to drop in your spheres, and thus makes it useless. Distilled water prevents this, because it contains no calcium.
*** I do not have one of these (yet), unfortunately. A lot of my mistakes will therefore come down to guesswork in the amounts I'm using.
The two main ingredients for spherification are calcium salts and sodium alginate. Applying them, however, can be done in two different ways.
A) Basic Spherification
For basic spherification, you mix your ingredient thoroughly with sodium alginate. Then, drip your liquid into cold water mixed with the calcium salt, where the process forms a membrane around the liquid drops within a few seconds/minutes. You then rinse them off before serving them in your dish.
B) Reverse Spherification
Reverse spherification is used for liquids that already contain calcium (like milk) or have a high acid/alcohol content. Because these things don't mix with the sodium alginate, you instead blend them with the calcium salt (if they don't already contain it), then drop them in a bath of water mixed with the sodium alginate. An alternative to this (which requires less active time) is frozen reverse spherification, where you freeze the liquid in a mold, then drop the spheres you've formed in the (warm) sodium alginate bath. As the outer edge of the sphere melts, the calcium salt bonds with the sodium alginate. Rinse off your spheres and serve.
Each technique has its pros and cons, but I'll be starting with frozen reverse spherification, because it's the simplest; the spheres are already formed in the mold, so you don't need to futz with the water bath to make the liquid ingredient form a sphere.
Step 1: Prepare liquid ingredient
In reverse spherification, you'll need a 0.18% calcium solution. In the case of calcium lactate, that's 1g per 100g of liquid (so not 100ml! Always measure by weight in these things, since they require rather a lot of precision, not unlike baking). I'll be using orange juice for simplicity. Sieve your liquid (to take out pulp, in my case), then put it in your blender and blitz the shit out of it. Add your powdered calcium salt as it goes along, and continue doing so for like five minutes (or longer). In some cases, mixing the calcium with a bit of sugar beforehand helps with dispersal.
Once your liquid ingredient has blended with the calcium, pour it in your silicone mold and put it in the freezer, preferably overnight. Meanwhile, you can prep your alginate bath.
Step 2: Preparing the Alginate Bath
To create the alginate bath, you'll want a 0.5% solution, so that's .5g alginate per 100g water. Similar to your the previous step, get your (distilled) water, blitz it in the blender, and pour in the powdered alginate bit by bit - if you throw it in all at once it might clump.
Once you've thoroughly combined the alginate with the water, it should feel a little bit slimy (but not too much) when you dip your finger in. Put it in an airtight container or cover it with plastic foil and chill it in the fridge (also overnight) to remove air bubbles caused by the blending, which will interfere with the spherification process.
Step 3: SPHERIFICATE
Once your ingredients and your bath have had the required waiting time pass, take your water bath and heat it up in the microwave till about 65 degrees Celsius, which is around 150 Fahrenheit. Then it's simple: drop your spheres in the water bath, wait around 2-3 minutes while gently stirring the water (and not touching the sphere in the process or letting them touch other spheres), take them out with a slotted spoon, rinse them in a clean bowl of (also slightly warm) water, and serve.
Except I didn't wait long enough, my first two spheres fell apart, so you'll have to wait overnight to see the results. Tomorrow!