Thank's Linuxboy, a great help as always!
Just one last question... I read that ash mellows the acidity and also helps to promote molds. So am I right in saying that the actual ash does not add any flavour, its more the molds it helps develop on the cheese that adds the flavour?
It's a difficult answer because I want to be exact. Ash from the crucible is about 95-97% carbon. The rest are elemental salts. There are also volatiles that are present that contribute to flavor and aroma. You can increase/decrease the amount of these volatiles by 1) choosing your feedstock and 2)By controlling the temperature. I'll give you a practical example. I make a bloomy rind full lactic curd log that I don't smoke, but that has a smoky flavor. The way I do that is by taking cherry and mesquite hardwood, making ash from them at relatively low temps (about 600F), and then pulverizing the results into a powder. The resulting powder definitely has a nuanced smokey, mesquite, deep kind of flavor and aroma. But it's not dramatic, just adds a layer of "huh, what IS that coy flavor. I must eat more"
As an another example, I like a very slightly aged lactic curd set with diacetylactis and Leuconostoc with geotrichum rind coated with ash made from herbs, carrots, garlic, celery, and onions. It's my mirepoix ash.The resulting ash most definitely has kind of a earthy, French kitchen sort of smell and a slight savory note. Again, not dramatic, but a supertaster would likely notice it and the aroma comes through especially for the fresh cheese. For this ash, I dehydrate the feedstock and I very very gently make the ash, just to the point where it's finished. It doesn't need so much time and heat as wood. And in this way I preserve the higher volatiles and aromatics.
If you buy your ash, it will be flavorless. Commercial ash destined for food grade preparation is washed, usually washed repeatedly. Sometimes it's acid washed to remove those salts I mentioned, leaving 99.9%+ carbon. This really is flavorless.
So does vegetable ash promote a different mold to say, coconut shell ash? Can ash be mixed to give a different flavor or is this so subtle it can not be identified?
No, the neutralization and drying properties of ashes are the same in terms of helping molds. Yes, if you make ash yourself you can definitely control the variables to craft unique flavors, but they will be very subtle. If you buy ash, it's either random vegetable base or coconut base. Not much more out there. Some specialty producers.. I know of only 1... make a hardwood ash.
I just have one last question ion this topic, how much does this contribute to the flavour? I read that coating cheese in ash
My cheeses are all about layers and complexity and terroir. So in the grand scheme of things, not terribly much. But it's definitely a flavor tool to be used in cheesemaking.