Remember the amazing "Soup and chocolate "between vineyards"" at Arzak that the wild boar raved about? We couldn't stop thinking about the little balls chocolatey goodness since then. The chocolate spheres have a thin membrane filled with chocolate liquid. They were extremely fragile and upon slight pressure, the spheres "exploded" releasing the creamy molten chocolate inside - amazing. The chocolate spheres were actually "spherified" (reverse spherified to be exact) - a technique widely used in molecular gastronomy. I will only do a brief introduction of what spherification is and won't bore you with too much details.
The spherification technique was introduced at el Bulli by Ferran Adria in 2003. It is used for encapsulating liquids within a very thin jelly-like exterior creating the famous el Bulli "caviar". There are two main types: basic spherification and reverse spherification. Both techniques involve two main components: sodium alginate and calcium ions (calcium chloride or calcium lactate is usually used). Sodium alginate is a high-molecular-weight polymer (a long chain of repeating molecules) with sodium salts and is an extract of brown seaweed used as a thickener, emulsifier or stabiliser in the food industry. In the presence of calcium ions, sodium alginate acts as a gelling agent. The calcium ions cross-link the alginate molecules forming a water-insoluble, gelatinous "mesh". Sodium alginate only increases the viscosity of the liquid, making it a bit "gummy" and doesn't impart any flavour.
Image from fooducation.org
Basic spherification involves submerging a liquid with sodium alginate in a bath of calcium. You basically blend together a small amount of sodium alginate and whatever liquid you want to spherify then submerge the mixture in a calcium bath. For liquid that already contains calcium like milk, yoghurt, cheese, chocolate and the like, reverse spherification is used - you submerge the calcium-containing liquid into an alginate bath. Simple.
NOT. There are a few more things that need to be taken into consideration.
As mentioned, basic spherification doesn't work if the liquid has a high calcium ions content. It also doesn't work with liquid with more than 20% ethanol, thus, for liquid that has a high content of calcium or alcohol, you will have to use reverse spherification. Calcium lactate or calcium gluconate is usually used to increase the calcium content of the liquid.
Besides, alginate is not soluble at pH less than 4. In other words, it does not work if the liquid is too acidic (Remember: the lower the number, the more acidic.). The best way is to check the pH value with a pH paper or an electronic pH meter, but for home experiments, here is a list of the approximate pH values of some commonly used fruits and vegetables. For acidic liquid, sodium citrate can be added to reduce the acidity level before the spherification process.
My first spherification experiment
OK, enough of facts, now, let's talk about my first spherification experiment! I got myself a Texturas spherification kit and a bottle of Gluco (a mixture calcium gluconate and calcium lactate for reverse spherification) from Infusions4chefs. The kit consists of the three essential ingredients: Algin (sodium alginate), Calcic (calcium chloride) and Citras (sodium citrate). Also included were the appropriate tools: two syringes - used to create drops that make spherical caviar; a set of measuring spoons; two collecting spoons - used to remove the spheres from the Calcic bath.
I was so excited when I got the parcel and couldn't wait to experiment with it. I raided my pantry right after I unwrapped the parcel to see what I can spherify, found a can of lychee, quickly checked its pH (here), 4.70 - 5.01, BINGO! I was feeling rather ambitious and decided to make more than just "caviar".
There are 5 major lychee elements in this dish: the fruit in its original form, lychee vodka granita, lychee jelly, lychee caviar and ravioli (giant caviar). The granita and jelly can be prepared the day before and the spheres are pretty easy to make once you get the hang of it. The height of the pipette to the bath and the way you tilt the pipette affect the shape of the spheres and it takes some trial and error to achieve good results. I got a lot of "teardrops" and "tadpoles" at the beginning. I had a lot of fun making this dish and also enjoyed eating it. Can't wait for my next experiment!
This lychee ravioli was left "cooking" in the calcium bath for 10 mins, so the membrane is a bit thick.
Textures of LycheePrintable recipe
Prep time: 30 mins
Set time: overnight
Cook time: 30 mins
Yield: serves 2
For lychee jelly:
- 1 canned lychee (565 g net weight, 227 g drained weight) - remove 2 lychees and leave aside for later use. Use the rest of the fruits (about 210 g) for lychee spheres.
For lychee and vodka granita:
- 1 leaf gelatin
- 100 ml lychee liquid
- 1/2 lemon's juice
For lychee spheres:
- 150 ml lychee liquid
- 1 tbs vodka
- 210 g lychee
- 40 g lychee liquid
- 2 g Algin (sodium alginate)
- 2.5 g Calcic (calcium chloride)
- 500 g water
- Prepare the jelly and granita the day before.
- Heat up the lychee liquid.
- Remove the liquid from heat and whisk in the gelatin leaf.
- Stir in lemon's juice.
- Pour mixture into a lightly-greased mould or container that holds 100 ml of liquid (I used 8x11x2 cm container) and leave to cool.
- Cover with clingfilm and refrigerate overnight till set.
- Mix together lychee liquid and vodka.
- Pour into a container and leave in the freezer overnight till frozen.
- Dissolve Calcic in water and keep this in the fridge while you prepare the lychee mixture.
- You should get about 210 g of lychees after removing 2 fruits for later use. Top this up to 250 g with lychee liquid.
- Blend the lychee until smooth and pass this through a sieve.
- Add Algin to 1/3 of the lychee mixture and blend until completely dissolved.
- Mix Algin-lychee mixture to the rest of the lychee mixture and leave to rest for about 1 hr so that it loses part of the air created by blending.
- Remove the calcium bath from the fridge and fill another bowl with water (this is to wash the spheres). You should have some lychee liquid left after making the granita, jelly and spheres, pour the leftover lychee liquid into another bowl (this is to "keep" the spheres). You should have 3 bowls altogether.
- For lychee caviar, fill a pipette or syringe (I used a 3 ml pipette) with the lychee mixture and expel it drop by drop into the calcium bath. The syringe needs to be high enough for the drops to sink when they get in contact with the bath but not too high or the drops may break into smaller drops creating “baby” spheres. Leave the spheres "cooking" for about 1 min in the calcium bath and then carefully remove them using a sieve. Rinse them very gently in the bowl of water to remove the calcium then transfer the spheres to the lychee liquid. Serve this immediately.
- I used a half sphere tablespoon for the larger lychee ravioli. Fill the spoon with lychee mixture and completely submerge the spoon in the calcium bath. Turn the spoon over and gently shake it to release the sphere. Leave the ravioli "cooking" for about 2 mins in the calcium bath and then carefully remove it using a slotted spoon. Then rinse it very gently with water to remove the calcium. Serve this immediately.
- The thickness of the membrane depends on the "cooking" time. Leave it longer in the bath if you think the film is too thin.
- For larger ravioli, always clean your spherical spoon after each ravioli, especially if you are placing the spoon bottom on the bath to pour the liquid. Also make sure your slotted spoon is clean before you dip it in the bath to fish your spheres. If you don’t clean your spoons, you may get small lumps of extra gel or “baby” spheres stuck to your sphere.
- The spheres have to be served right after the spherification process to conserve their inside liquid. The jellification process continues even after removing the sphere from the calcium bath and will eventually convert into a solid sphere with no liquid inside.
- The liquid in the lychee ravioli was a tad too viscous, would suggest diluting this before the spherification process.