...you know how you pour a beautiful cup of coffee... at my shop, it happens to be french press, and then you toss a little soy milk in there (either hot or cold)... and then the cup transforms from some chemical reaction into some "bottom-of-the-river-yucky-muddy-visual-mess"--why is that? and why is it only with some brews?
I'm no expert, however, I think it has something to do with the varying amounts of oils/fats in each coffee and the brewing method used (paper filters hold more oils from the end product?) and the oils and fats in each different brand of soy. I have only seen it do this in certain soymilk brands with certain coffees. definately strange... sorry for the incomplete and possibly wrong answer.
This is a reaction between soymilk and high acidity coffees; in some extreme cases, it'll do the same with light cream. We direct soy-drinkers to some of our darker roasts which don't have that problem. (We're using Edensoy Original)
Haha, definitely had that situation come up before :D We were pretty stumped as to what was going on, but we were determined to fix it for the guy, even though he just set it on the counter and said "I'm good, really, thanks". Steaming did help a bit, at least to make it palatable for him.
I think the temperature of the coffee could be one reason also. I've experimented with it before with a freshly brewed, super hot cup of coffee. I put some ice in it just to cool it down slightly, then I put some soymilk in it and didn't see any clumps, but when I put soymilk in it without cooling it down, clumps all over the place! But the acidity level makes sense too. Didn't think of that before.
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