In my lab - Foams, part 4, Lecithin

Lecithin is a fatty substance that occurs naturally in lots of animal and plant tissues. It is the lecithin in egg yolk that makes the yolk work as an emulsifier. It also works as a foaming agent. According to this page it is most often used at a ratio of 0.25% - 1%. Let's try it out.

I added 1g lecithin to 300 grams of water. That makes 0.3% of lecithin.

I poured this into a wide, low container and whipped it using an immersion blender. Since the goal here is to add air, I held the blender so that half of it was over the liquid and half of it in the liquid. This may be a bit messy, so you may want to put a cloth or something over the part of the container where the action is. This resulted in a bit of foam that could be spooned out onto a plate, but nothing celebrate, really.

Same thing now, but with 3g of lecithin. This makes 1% of lecithin in the
water. this time there is much more foam, and it seems to be stronger as well. When spooning this out I get a good height on the plate. The foam seems quite stable. Bubbles are of medium to large in size, so the foam is quite coarse. It also feels quite dry and is very light. This is perfect for what is known as an air. The liquid used to make this must have a really strong taste because there is very little of it, the foam is mostly (normal) air. This can be used to add subtle flavour nuances to a dish without drowning the dish in sauce.

So the foam we created above was quite dry. There is very little of the liquid
in it. If we want it to be wetter and containing more liquid, we need to thicken it. I will try to add Xanthan. According to some sources I have found, Xanthan is typically used in a ration of 0.1% to 0.5% to do this. So I mix 300g of water with 3g of lecithin and 0.3g (0.1%) of Xanthan. The resulting foam is more heavy and wetter containing more of the water, but also, because of that it cannot support itself and sits flatter on the plate. It seems quite stable, though.

Let us see what more Xanthan does. 300g of water, 3 grams of lecithin and
1.5g (0.5%) of Xanthan. The liquid is quite thick before whisking, and the resulting foam is very wet, but it is so heavy that it just sits on the plate as a shallow, airy mass. Also, the bubbles seem to be a bit bigger now. Not very exciting.

But what would this be like using a whipping siphon? I mix 300g of water, 3g of lecithin (1%), some red colouring and 1g (about 0.3%) of Xanthan. I mix this with the immersion blender, pour it into the ISI whip, charge with one canister of N2O and shake vigorously. This gives me a quite fine foam with small bubbles, but it is not very strong. Since the foam is quite wet, it cannot hold its shape. It seems quite stable, though.

I try to double the amount of lecithin, using 6g. The foam i a bit firmer, managing to stay in a lump in stead of just floating out. Nice wetness, but at this concentration I think I can start tasting the lecithin, and we do not want that.

What if we just add another charge to the same siphon now and give it another shake? The foam seems a bit stronger having slightly more height, but I really do not think this is the way to go. I also try adding no Xanthan, only lecithin as we did when whisking up that air. In the siphon that does really not work at all. No foam, just squirting liquid all around.

So let us go over board with the Xanthan. 300g of water, 3g of lecithin and 3g of Xanthan. This time the goo that I pour into the ISI whip is quite thick. When dispersing, I get a nice, wet foam with very fine bubbles. It really has a good mouth feel. It also holds a bit of shape. I sort of like this one. Almost like a foamy sauce.

As a last try, what if we did the same, but without the lecithin? With only 1% Xanthan? Wet slime with bubbles and not really any hold to it.

So I think the conclusion for lecithin so far is:

1% of lecithin for a good "air". Perhaps with a tiny amount (0.02-0.05%?) of Xanthan to give it more wetness, but not so much as to collapse the bubbles. Whisked using an immersion blender.

1% of lecithin and 1% of Xanthan for a very light creamy foam using a siphon.


Below: Pan fried cod with carrots and lemon air.