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How to Make Coffee With Soya Milk Without It Curdling

I love coffee, but I'm vegan so I don't drink cow's milk. I wanted to find a way to make coffee with soya milk without the milk curdling.

The soya milk is starting to curdle yet again! Argh!

The soya milk is starting to curdle yet again! Argh!

How to Stop Soya Milk Curdling in Coffee

If you’re anything like me (and I hope for your sake you’re not), you love coffee but don't want to use cow’s milk—perhaps for health, taste, or ethical reasons.

If that’s the case, then you have undoubtedly come up against the big curdling conundrum: Just how do you make coffee with non-dairy milk, like soya milk, without it curdling? In this article, I will attempt to help you in your quest to make a perfectly smooth, non-dairy milky coffee. For those of you looking for a quick fix, I’ll even show you which product has been designed to solve this problem once and for all.

For many years, unable to solve this issue, I drank my coffee black with a spoonful of honey. I loved it, and it meant I no longer had to worry about curdling milk. But then my dentist persuaded me it was time to ditch the honey. I protested vehemently, but it was no use: I knew the time had come. So I set about trying to make coffee with soya milk once again, just as I had tried to do many years ago.

Operation Curdle Prevention: 11 Experiments

Over a period of several weeks, I researched this issue and tried a number of experiments. Here are the various attempts I made at making the perfect coffee (I used instant coffee in these experiments):

  1. Add water to coffee and then add soya milk.
  2. Add the soya milk first, then water, then coffee.
  3. Mix the coffee with the soya milk first and then add water.
  4. Warm the soya milk first, add water, then coffee.
  5. Warm the soya milk first, add coffee, then water.
  6. Allow the boiled water to cool before adding it to the cup.
  7. Leave the spoon in the mug after mixing soya milk, water and coffee.
  8. Shake the carton of soya milk first or whisk the milk in the cup before adding water and coffee.
  9. Pray to the Goddess of Lattes.
  10. Try different brands of soya milk.
  11. Try a different type of non-dairy milk.

Disappointing Results

Several of the experiments seemed to work initially, only to stop working as soon as I began to think I may have cracked it. With my initial attempts allowing the boiled water to cool quite a lot before making the coffee seemed to work best. This was fine but resulted in several cups of lukewarm coffee, which was not ideal.

Whisking the milk was interesting and made the coffee taste nicer but all that did was make it harder to tell if the milk had curdled because it took several slurps to get through the froth. Unfortunately, below the froth, there was the usual curdle.

Allowing the boiled water to cool before making the coffee certainly makes sense from a taste perspective ("coffee boiled is coffee spoiled," after all) but it was interesting to note that adding boiling water to soya milk alone doesn’t make it curdle. It only curdles once the coffee has been added.

I tried two brands of oat milk: one made from only organic oats and water; and another which had added ingredients like sunflower oil. The one containing the oil worked better but personally speaking I don’t really want to be adding oil to my coffee.

A Miraculous Discovery

Eventually, after praying to the Goddess of Lattes and looking online for a magical spell I could use, I tried using a different brand of soya milk. I live in the UK, and up until that time I had been using a supermarket brand of organic soya milk. It was unsweetened and had no added ingredients—it was just organic soya beans and water. But it wasn’t working.

So then I tried Alpro organic unsweetened soya milk, which seems to have identical ingredients. The result? Bingo! I made a milky coffee that didn’t curdle—and it was hot! So I tried again. And again. And again. Each time it worked. Curdling was a thing of the past.

So what was the difference? Both the supermarket (Tesco) brand and the Alpro soya milks were organic, unsweetened and had no added ingredients. So why does the Alpro milk work when the Tesco one doesn’t? Perhaps it has something to do with the beans, the water or the manufacturing process.

Why Does Soya Milk Curdle in Coffee?

My experiments led me to believe quite firmly that the Goddess of Lattes is capricious and very difficult to placate. I suspect she has a particular liking for cow’s milk and doesn’t like this new-fangled soya nonsense. But the general consensus in the scientific community seems to be that soya milk curdles in coffee because the coffee is acidic.

With that in mind, I did try making ground coffee in a cafetiere, in the hope that it might be less acidic, but that didn’t work when I was using the Tesco milk. So then I had a look online for some low-acid coffee, but there doesn’t seem to be a great deal available over here. If you live in the US, I believe low-acid coffee is easier to come by, so if you haven’t been able to solve the curdling problem any other way, that might be worth a try.

Still on the subject of acidity, some soya milks contain acidity regulators and some people believe these can prevent curdling. I tried the Alpro non-organic unsweetened soya milk, which contains acidity regulators, and that has worked for me every time, but so does the Alpro organic unsweetened version which doesn’t contain acidity regulators.

2020 Update: Oatly Barista to the Rescue

Sometimes to solve a problem you have to think outside the box. Or, in this case, outside the carton. A few months ago I went into a coffee shop and asked if they had any soya milk. "No, but we have Oatly Barista Edition oat milk, which makes a mean latte." So I gave it a go.

Man, that was THE best coffee I have ever had. Finally, a definite answer to the question of how to stop soya milk curdling: don't use soya milk! Who'd have thunk it?

Since that day, I've been a total convert. No more soya for me.

I recently made a coffee for a friend who usually has cow's milk. He's used to me giving him some kind of plant milk, but this was the first time he'd tried the Oatly Barista milk, and he said it tasted great. He said it tasted really creamy and just like proper cow's milk. He even got his wife to start buying it!

Thank you, Goddess of Lattes, I knew you were listening all along!

Please feel free to share your own experiences by leaving a comment below. Happy drinking!

Questions & Answers

Question: Have you tried Alpro soya chocolate milk? I have been drinking it in my coffee for a few days, and have now googled it to see if anyone else has done this, only to read that the drink curdles! I think it tastes yummy but should I continue to drink it?

Answer: Hi, I personally haven't tried it but it sounds nice. I guess if it doesn't curdle when you use it, why not continue drinking it?

© 2018 Rob Butler