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March 14, 2016 9:21 AM   Subscribe

Why does almond milk curdle in my cold brew?

Almost every time I put (fridge cold) almond milk into my cold-brewed (also fridge-cold) iced coffee, it curdles.

I googled this and got a host of ill-informed people on nutrition and fitness forums insisting that this simply doesn't happen, but it does. It seems to happen regardless of brand, shelf-stable vs. almond milk from the fridge section, etc. It's NOT an issue of the almond milk being too cold and the coffee being too hot, as I'm adding cold to cold in this situation.

I'm fine drinking the broken almond milk, because I know it's not "rotten" per se just chemically broken up in an unsightly manner. But I'm curious about what causes it.
posted by Sara C. to Food & Drink (10 answers total) 1 user marked this as a favorite
 
Acid is another thing that curdles proteins. A quick search indicates coffee is acidic with a pH of around 5. Try a splash of almond milk in a shot of vinegar (pH 2.4) and see if that has the same result.

Hmm, apple cider vinegar appears to be much closer to coffee in pH.
posted by Sunburnt at 9:39 AM on March 14, 2016


The acids in the coffee are coagulating the proteins. The higher the acidity, the more coagulation. Cold brewed coffee is much more acidic than hot brewed coffee. You may be able to reduce coagulation by making a hot brewed concentrate in an aeropress or similar, refrigerating it, then adding water and milk to taste.
posted by xyzzy at 9:40 AM on March 14, 2016


I often see particles of fat from the almonds floating in my coffee (hot or cold), but I don't see curdling. Are you seeing a few flecks, or the entire volume of almond milk separating and settling?

If it's the latter, you're most likely seeing an acid reaction. I can't think of anything to change the pH of your coffee other than looking for low acid beans (do those exist?) or emailing almond milk manufacturers to find out if any have been very finely homogenized or otherwise intended for use without curdling in acidic beverages.

If it's the former, that won't go away. I've never met an almond milk (commercial or homemade) that completely homogenizes the fat content or fully reduces insoluble particles to invisible sizes.
posted by late afternoon dreaming hotel at 9:43 AM on March 14, 2016 [1 favorite]



I often see particles of fat from the almonds floating in my coffee (hot or cold), but I don't see curdling.


This was me also. Are you shaking the hell out of it before you add it to your coffee? Try that and see if the "curdles" are smaller. Hot coffee can dissolve the fats back into liquid. Cold coffee won't.
posted by jessamyn at 9:47 AM on March 14, 2016


Have you tried pouring the coffee into the milk rather than milk into the coffee? That seems to work for me, sometimes.

I have also read suggestions of shaking the milk vigorously before pouring it.
posted by like_neon at 9:47 AM on March 14, 2016


Cold brewed coffee is much more acidic than hot brewed coffee.

I was under the impression that the opposite was true- that it's LESS acidic.

However- the molecules in cold liquids are moving around more slowly than those in cold liquids. I wonder if the agitation of hot coffee might make this effect less noticeable.
posted by showbiz_liz at 10:05 AM on March 14, 2016 [2 favorites]


I have definitely found that shaking the almond milk fixes the problem most of the time. My assumption has always been the acidity of the cold brew.
posted by Night_owl at 10:08 AM on March 14, 2016


However- the molecules in cold liquids are moving around more slowly than those in cold liquids. I wonder if the agitation of hot coffee might make this effect less noticeable.
That may be the case and I'm probably wrong about cold brew being more acidic. I noticed coagulation problems with just normal creamer when I tried cold brew a few summers ago and assumed that it was more acidic as a result. For all I know it was the particular coffee I was using.
posted by xyzzy at 10:14 AM on March 14, 2016


This happens with soy milk too for very acidic coffee. I started adding a pinch of baking soda to my coffee grounds before I poured the water over it to make it less acidic. Maybe you could mix it in before you add the milk?
posted by Toddles at 2:12 PM on March 14, 2016




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