I am following a recipe for oatmilk, consisting on 1L of water, 100gr of oats, a pinch of salt and desired sweetener. This recipe let´s them soak and also blend them for 2 minutes before filtering it in a cloth to get the solid out. The result is then slimy oatmilk, which I like and it seems it's due to Betaglucans and it seems healthy. I know how to make it non-slimy, not soaking, not blending for more than 30s.

After letting sit the oatmilk, I can see a division of densitities between the more watery part and the part that has more "oaty" content.

Measuring the calories of this drink makes me think it can vary depending on the process... I assume that in the state the milk was in the picture, the watery substance had less caloric value than the bottom "oaty" liquid. We can also weigh APPROXIMATELY the grams of oats filtered with the cloth. But then if the oats were blended for less time and they were also harder (not soaked, not softer), ergo, non-slimy milk, it means that the solid residue to filter with the cloth will be bigger? Decreasing the caloric value of the drink?

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Is there any intuitive way (not using a bomb calorimeter) to determine an approximate number of calories for this type of liquids? Do Betaglucans have any impact on the process?

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    It’s going to be dependent on what dissolved in / was extracted by the water. So it won’t just be a ratio of how much weight the oats lost (after being dried)…
    – Joe
    Jul 12 at 12:17

1 Answer 1


I would say that your options are pretty limited, but it also depends on what your expectations are, exactly.

First, it's unclear if you want to measure or calculate the calories.

The "calculate" part is much easier to cover: you can't. Calculating calories only works when you are combining ingredients, then it's simply the sum of the ingredients. But when you're taking away part of the ingredients, there's no way to calculate how much is left. You'll have to measure it empirically.

Your suggestion of approximating by the weight of discarded oats isn't workable. You're soaking your oats, so you'll probably discard more weight than the weight of the dry oats you're putting in. This doesn't mean that your milk has negative calories, but simply that you're discarding some of the water along with the oats - and you don't know how much.

As for measuring, then it's unclear what you mean by "intuitively", since measuring is the opposite of intuition. If you're asking for a method that is doable under home conditions, the answer is "maybe".

There certainly are ways to rig a simple calorimeter at home and use that. It doesn't even have to be the "bomb" type. You can find many descriptions around the Internet, intended for kids' science projects and the like. You'll run into several problems:

  1. It will require a lot of time investment on your side
  2. A simple homemade device will probably be rather inaccurate. You can of course try to calibrate it, by using published calorie tables and foods which aren't likely to vary much from one sample to the next, such as plant oil or sugar. But you'll probably have to do a lot of experimentation series until you have an inkling of how reliable your measurements are.
  3. Your oat milk is liquid. You'll have to dehydrate it completely before burning it in a calorimeter. As you don't have access to industrial methods, you'll have to choose a slow dehydration method - during which enzymes and bacteria can change the composition of your oat milk (although this will likely cause a shift in the macronutrient composition rather than a big change in total calories)
  4. It's unlikely that you're able to produce consistent results between batches of oat milk. So even if you can overcome the practical problems of creating a measurement, you'll end up with a somewhat broad range. Although that last part is inherent in calorie counting anyway, and the major databases simply list an average value.

It's of course up to you to decide if you want to invest all the time needed just to get some approximate results. If I were counting calories, I would probably simply opt for counting the calories in the oats as an upper limit, and call it a day.

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    I basically agree, but drying the discarded oats could in principle come up with the discard weight. The problem is there's dry and there's dry - the water content will never be zero in the bought oats or the discarded ones. Any approach like this also has to make an assumption about whether the weight retained in the drink has the same composition as oats, or is more starchy or more fibrous. This would still provide a better upper limit than assuming you consumed all the calories in the oats
    – Chris H
    Jul 12 at 15:37
  • @ChrisH: you could also dry a sample of the initial oats to determine their water content. But even with a bomb calorimeter to test the remnants, you’re not going to get truly useful numbers as part of the issue is how bioavailable those calories are
    – Joe
    Jul 12 at 16:13
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    @Joe bioavailability isn't taken into account in standard tables, to which we might like to compare the result. So I doubt we need to worry about it. But I'm addressing the beginning and end of the answer, about estimating - as much as the idea of making a calorimeter appeals, it doesn't seem realistic
    – Chris H
    Jul 12 at 20:47
  • Great answer, thank you very much! Indeed, intuitively was not the word! I meant "something more or less accurate but doable to do at home without lots of equipment". I will do some more research and decide what to do, but you lit a little bit the path. Thank you as always! Thanks also to @ChrisH and Joe! (cannot tag 2 users)
    – M.K
    Jul 13 at 7:30

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