I have tried making soy milk powder from store bought soy milk. I used my dehydrator, but a few hours into the process the milk was starting to smell sour. I have seen recipes that make soy milk powder from the soybeans itself, but I have no access to soy beans.

Has anyone have had succes making soy milk powder this way? Is it possible to dehydrate store bought soy milk without it turning sour?

I am thinking of trying dehydrating almond milk next. The goal is to make an instant chai latte powder. I like my chai latte best with soy milk but am open to whatever plant-based milk will dehydrate properly.


  • Given your goal, have you looked for commercial soya milk powder. I could get a couple of brands online in the UK
    – Chris H
    Mar 10, 2021 at 10:40
  • The only commercial powders are baby formula ones. So full of sugar also. In my pantry I have Soy Protein Isolate, I’m wondering if this would do the trick?
    – Lauwchen
    Mar 10, 2021 at 14:05
  • This US brand is available internationally and has no added sugar.L amazon.co.uk/Pure-Dairy-Free-Milk-Powder/dp/B07DGC3S3K Some have lots of sugar, you're right. Others have a few %, comparable to the lactose (i.e. sugar) in cows' milk
    – Chris H
    Mar 10, 2021 at 14:14
  • It might help if you tell us where you are
    – Chris H
    Mar 10, 2021 at 14:17

1 Answer 1


You are going about the process the wrong way - the milk powder in this case is made of pulverized soy beans. Once you add water to this powder to make the milk, it will be very difficult, time consuming and expensive to dehydrate it to make the powder.

The reason your dehydrating milk is turning sour is either that it has picked up some bacteria or yeast from the air or contact with a slightly contaminated surface and these are growing happily in the nice warm dehydrator, similar to making yoghurt from milk. The other possibility is that there are some (bio)chemical changes going on with the heating which result in a sour taste. I would put my money on the bacteria/yeast option.

Your best bet will be to buy some dry soy beans, soak them to remove any dirt, then dry overnight, roast to denature proteins then pulverize them yourself. You can use a blender/spice grinder to do much of the work, but to get it fine enough to work well as milk, you might need to do a bit of manual labour with a mortar and pestle. There is a recipe here.

  • I know this is the right way to make soy milk protein, but I cannot find a store (online or elsewhere) that sells raw soy beans. Thanks for your answer!
    – Lauwchen
    Mar 10, 2021 at 14:07
  • @Lauwchen They would be listed as dry or dried soybeans. The product listing won't specify "raw" but that's what they are. I found many, many product listings by googling "bulk soy beans dry," eg this listing for organic soybeans, 25 pounds for $35. Just make sure you buy soybeans intended for human food, not for animal feed or for planting.
    – csk
    Mar 11, 2021 at 6:30

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