Frothy milk question

Mrs Belgium and I like a cappuccino in the afternoons (decaf, of course) and make ours at home using a milk frothing jug rather than a jet of steam.
Now, sometimes the milk will go so frothy it’ll pour almost like whipped cream, yet other times no amount of vigourous wrist action (ooh err) will make it froth up.
It doesn’t seem to correlate with using milk from any given shop (Sainsbury’s, Waitrose, Co-op or even the petrol station), or whether it’s organic or not, it just seems totally random.
Anyone got any ideas how and why this is happening?

pus content, use skimmed and steam up to about 65degs

MrNutt – Member

pus content, use skimmed and steam up to about 65degs

…if I had a steamer, I would.

milk in pan, boil and whisk? thats how i make hot chcocolate and it goes ridiculously frothy and stays that way if its full fat or you add a dolop of cream.

He’s not asking how to froth milk, he’s asking why it varies. And there are many articles on the net about this; I’ve read a few but can’t bring to mind any references. But here’s what I remember:

The bubbles are made possible in milk because of the protein. The long molecules get tangled up and produce the tension needed to create a bubble film. However, fat tends to help stop this happening (can’t remember why) which is why skimmed and full fat behave differently. Skimmed, without fat to inhibit the bubbles, produces a load of thick airy foam which isn’t too nice. Full fat on the other hand produces lots of small bubbles making the result creamier in texture but it doesn’t stay as long. The foam on skimmed can last ages, until it all dries out, but it’s just foam and not lush creamy head.

In any case, the protien content of milk varies based on the cows it’s from, and where and what they’ve been eating. The more lush their pasture, the better nourished they are and the more protein in their milk. Of course, when you buy Sainsbury’s own, it could have come from anywhere, so it’s going to be quite variable. I believe it was an Australian company that produced carefully selected and tested milk specially for making cappucinos that had consistently high protein content.

I would suggest trying milk from as consistent a source as possible, but that’s hard in a supermarket setting. Maybe a farm shop or something, or some kind of expensive branded milk. Of course, even that won’t necessarily be super consistent cos there’ll probably be a seasonal variation.