I’m kind of embarrassed to admit that I have been playing around for a while and have been keeping a secret of it.
I’ve been fixated with molecular gastronomy – more specifically – spherification. This is the technique that lets you make little spheres of ‘caviar’ – a thin gel membrane holding a liquid that bursts in your mouth. It’s totally amazing! OK yes, it’s total wankery too, and is perhaps a bit ‘so last year’ now. But it’s a challenge and it made me feel a little like Heston (without the genius).
My preferred method is reverse spherification, as 1) it can be used for a variety of liquids, including dairy; and 2) the spheres can be different sizes and last a lot longer. Most importantly, from what I’ve read, it’s easiest to get to work. My spheres are rarely never very pretty and I usually ‘hide’ them in food, like a mousse. There’s still the wonderful mouth pop of fruit. The down side is that you can’t dispense too many in the special bath at once, or they fuse together. So I don’t tend to make more than 10 in a batch, which means to make enough for a recipe (about 50 balls), it takes me about an hour.
Getting this right requires special equipment (and believe me, you can really go to town here) – I have (limited myself to) a slotted tablespoon and a couple of syringes (I find a 25 ml works better than a 10 ml syringe). The larger the volume of the syringe, the larger the droplets. That said, mine often end up looking a bit like worms and usually have little tails…. to be honest, it’s just practice and patience. My first few goes were disasters.
I have also used a round-bottom 1 teaspoon measuring spoon for grape-sized spheres – be patient, they may start off looking very distorted, but they do eventually form spheres as they move around in the bowl.
I cannot recommend enough:
1) looking at a few YouTube videos of the techniques; and
2) not trying this for the first (or second) time on a dish you really care about presenting!
I’ll post a few things that I have made with this method over the coming weeks, including mousse cakes flavoured with fruit caviar and cheesecake balls. It’s been great fun.
This is my GO TO place for Molecular Gastronomy
For the berry puree
- 1 punnet strawberries (or another fruit – adjust sugar and acid to taste)
- 2 tablespoons caster sugar
- 1 teaspoon lemon juice
- ⅛ teaspoon Calcium Lactate Gluconate Powder (2 g per 100 ml)
- Xanthan Gum Powder (if required 0.2 g to 0.5 g per 100 ml)
- Place fruit and sugar in a pot on the stove top and heat until sugar starts to caramelise and fruit is soft.
- Pass through sieve to remove seeds.
- Set aside to cool (should be a bit over ½ cup –approx 125 ml).
- Add Xantham gum if not thick enough – it needs to be the consistency of thick cream (0.2 g per 100 ml turns something with water consistency into a cream-like consistency – 0.5 g per 100 ml will make a cheesecake-like consistency).
- Add calcium lactate gluconate and mix thoroughly (though not so much that froth is formed – I have a teeny-weeny whisk for this).
- Leave to rest.
For the sodium alginate water bath
- 5 g icing sugar
- 5 g Sodium Alginate Powder (0.5%, or 5 g per litre water)
- 1000 ml distilled water
- Mix the icing sugar and sodium alginate together and place in the bowl of an immersion blender with half the distilled water.
- Blend for at least one minute. Then add the rest of the distilled water.
- Pour into large clear pyrex bowl, cover with cling film and leave in the fridge to rest for at least 4 hours to remove the air bubbles (recommend 1 – 24 hours).
To make the magic
- Set up a bowl of fresh water next to the sodium alginate bath.
- Fill a syringe with the berry compote/calcium.
- Place the barrel of the syringe into the sodium alginate bath and slowly and carefully dispense a droplet under the liquid while raising the syringe towards the surface.
- Let the little spheres fall to the bottom of the bowl and gently tease with a spoon so all the surfaces get exposed to the water bath.
- Alternatively (for larger spheres), fill a 1 teaspoon measuring spoon and carefully pour out right over the surface.
- These larger spheres will form as they penetrate the water bath due to surface tension. Allow the spheres to fall to the bottom (or ‘help’ them sink with some gentle agitation).
- If the fruit mixture just spreads across the surface, then it is too thin – use some Xanthan gum to thicken it up a bit.
- Leave the spheres in the sodium alginate for a couple of minutes to form a solid gel membrane and ‘set’, then carefully remove with a slotted spoon and rinse in the water bath.
- Scoop spheres out of the water bath to a clean container.
- The spheres can be used immediately, or set aside until needed by storing in liquid to prevent them drying out. Store the caviar in a solution of fruit juice (same as what they are made from), rather than water – or they will dilute due to the wonders of osmosis.
Now some hints:
1) Do you really need distilled water? Probably not, especially if your tap water is not too hard – Canberra’s water is typically quite soft. However, I’ve use distilled water with good results. It’s about $3 a litre in BigW.
2) Never try to hydrate the sodium alginate in warm water!
3) I have had great success doing reverse spherification with diary products, such as yoghurt and cheesecake, though I still add calcium to help with a firm gel membrane.
4) Bigger spheres can have a strange ‘mouth feel’ when they burst in your mouth compared to small (pea sized) caviar – that’s my opinion (I think it’s the thickness of the membrane required to hold together a larger sphere). I never try to make anything bigger than a grape, unless it’s just for show and breaking over something.