I heard recently that adding Sodium Citrate, also known as Sour Salt, to your cheeses when trying to melt them into a cheese sauce supposedly helps keep the cheese from becoming all separated and greasy. Has anyone tried this? I would love to know if this works, because I've wasted many a block of good cheese trying to make a fancier version of Mac & Cheese, only to have it wind up a mess because the particular cheeses I bought didn't melt well.
I can't say that I have heard of it but that would be nice if it works! If I am working with a cheese that I know will separate, I will make a basic white sauce and just add some shredded cheese to it. This will give you a good cheesey flavor and seems to prevent the cheese separation issue. To make the basic white sauce you just make a rue with butter and flour, then slowly add milk using a whisk to prevent lumps, cook until thickened, remove from heat and then add the shredded cheese. It doesn't take much cheese to get a cheesy flavor either!
That's how I'd always been taught to make cheese sauces, start with a roux. I have mixed luck with them though, sometimes they go from creamy to paste in the blink of an eye. I've also heard it helps to take the roux off the heat when you add the cheese, and let the cheese gently melt into it. Something about melting it too fast and/or overheating it can also cause the cheese to separate. Another method I use from time to time, is just to heat some heavy cream in a double boiler and gently melt my shredded cheeses into that. I've had some success with that, but found the sauces don't hold up too well to being baked afterwards, such as if you're trying to make a baked mac and cheese. But if you're just looking for a plain creamy mac and cheese, it works fine.
I hadn't thought about it before but I do always take the roux off of the heat before I add the cheese to it.If it does get too paste like, I slowly add milk or cream while whisking it to thin it out. There have been a few times that I have needed to strain the lumps out though. I also only bake the mac and cheese just long enough to lightly brown the very top. Because everything is already cooked before I put it in the oven, there is really no need to bake it very long.
