I am trying to break down the starches in a certain variety of oats in the most efficient way possible. I have to break the whole oats down after cooking, so they are finer particles for the amylases (alpha amylase and gluco-amylase) to do its work in the liquid.

I have been adding the amylases at the beginning of blending of the whole oats (at a temperature of about 35 centigrade) because I thought it would help the enzyme process, but could I be damaging / denaturing the enzyme from the shear forces of the blender (I am using a 600 Watt stick blender)

The next stage is where I bring the oat and amylase mix up to 60 - 70 degrees c to get the most effective breakdown of starch

  • 1
    An enzyme is a pretty small molecule. I haven’t read the paper, but I don’t think it’s very likely.
    – mreff555
    Jan 21, 2021 at 3:09
  • Check the recommended temperatures and pH ranges for your enzymes. Enzymes from different sources have different best ranges, not all are the same as barley malt. For some grains you will also need to check gelatinisation temperatures, but oats are around 60C so you should be fine there.
    – Jack
    Apr 16, 2021 at 2:40

1 Answer 1


Good question. No I don't believe mechanical forces can break down enzymes to the extent that it would be a concern. Viewed through a magnifying lens or microscope, blender blades will have a relatively enormous surface area compared to your enzymatic molecules. The blade will push the enzymes around but the only damage done potentially could be if the blender heats up from running for a long time. So: Mechanical damage, no, not a concern. Heat damage, remotely possible to damage, but very unlikely unless perhaps running the blade in the same batch for many hours, and even then... unlikely.

The key of course will be to quickly bring your oat mash to 60-65 C and hold it there for at least an hour. 90 minutes might work even better, depending on your goal for saccharification efficiency, and, (I am assuming) fermentability and attenuation later on. There will not be a great deal of enzymatic activity at 35 C, so I would not keep it there for too long unless perhaps it is most convenient for your process.

  • 1
    Thanks for your answer. I did a test yesterday, blending the cooked groats with cold water to bring the temperature down to about 37 centigrade and making a relatively thick paste (i had to add more water). I then stirred in the amylases at this temperature and it immediately transformed into a thinner liquid - so there is definitely some quick activity going on at that temperature! But yes, most of the real sweetening happens around 60 - 75 C. I think I'll need to get a proper brewing urn.....
    – Amphibio
    Jan 20, 2021 at 8:10
  • This paper also suggests shear forces might be an issue, but I have no idea if the kind of forces from a normal blender are applicable - pubmed.ncbi.nlm.nih.gov/15296441
    – Amphibio
    Jan 20, 2021 at 8:13

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