any tips on holding and making foams? I have to make a foam at work and sometimes it just doesn't seem to happen. I use about 2 tablespoons of soy lecethin for every quart of water. I know it works better warm...
help with foam
There is no ideal ratio to use for all foams (or airs as I would call them) since it depends on what liquid you are using, at what temperature and the fat content so really you just have to find a recipe that works or develop one yourself. For anything "molecular" it is important to get a set of accurate micro scales so you can measure to at least 0.1g. Most of the airs I used were around the ratio of 0.3-0.8% of lecithin to liquid. Also you have to use a good stick blender, I always used a bamix with great results but when I used a cheaper one during one service it didn't really work as well.
As for holding, it depends on the temperature you want it held at. If you want it hot then you could use a pot in a bain marie with a lid or saucer on top to stop it evaporating. I used to keep all my sauces in little pots in a bain marie with saucers on them and used a marker to name them. It's never a great idea to hand your chef the wrong sauce for a dish if you don't want it thrown back at you. And yes, unfortunately I am talking from experience.
If you want more specific advice I'd need to know what you are trying to make into an air. There is a free recipe collection to download here http://blog.khymos.org/recipe-collection/ have a look at the lecithin section, it's also a good site to have a rummage in. Let us know how you get on and good luck.
Foams are all about trial and error and there are not really that many ground rules to follow. The link posted above is excellent and is about the only good resource online.
Soy lecathin will froth just about anything and I use a general ratio of 1tsp to 450ml (1pint) of liquid but you have to bear in mind the ingredients you are using. Lecathin needs some degree of fat for best results and it will emulsify water into oil, I use it in vinaigrette to stop it from settling out. Lecathin is also better for hot or warm foams as agar and gelatine dissolve with heat.
I don't understand why you are using water to make a foam as this would surely dilute any flavor profile you are trying to create. Without knowing the type of foam you are making it is difficult to offer suggestion, however if you think about it there are many ingredients that will do the job. Egg whites and powdered milk work very well in some applications.
One final thought, Have you considered using an ISI cream whipper? they make life a lot easier.
iSi canisters care great, but pricey. We use a gelatin base for our cold foams, and for hot foams, we use lecathin and an immersion blender. The trick to using the handheld with hot foams is to make sure you are getting air into the mix. No air, no air bubbles. No air bubbles, no foam.