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Chitosan – what to look for in a product

When purchasing a chitosan solution it is important to know that you are receiving the genuine article. Regardless of whether you are intending on using chitosan as a biofungicide, a biostimulant, a water treatment flocculant; the properties that need to be looked for remain the same. Over the years, we have been sent samples of many products that purport to contain chitosan. However, when analysed in our lab, they contain little to no chitosan.

A freshly made batch of chitosan concentrate

The good news is that you can use these simple tips to know if your product contains active chitosan:

Light-brown colour

Chitosan should be a light-brown colour.

If it is clear, then the chitosan content will be very low (or absent).

If the chitosan is black/dark-brown, it is likely that cheaper humate has been added to bulk out the product.


A solution of chitosan should be a gloopy liquid, like honey. This is especially true if you have a concentrated solution, such as Eutrema’s 5% solution.

Clear solution

There should be nothing floating in a chitosan solution, and there should be no sediment. You should be able to see through the liquid when placed in a beaker.

No odour

Chitosan does not have a strong odour. If a product has a strong odour, it is not coming from the chitosan.

Mildly acid

Solutions of chitosan should be mildly acidic. If they are neutral, or alkaline, there will be NO chitosan dissolved in it. Chitosan is not soluble in alkaline conditions.

Fully soluble

If the liquid does not dissolve in water, it is not chitosan. It may be ‘chitin’, but even though chitosan comes from chitin, it is not the same compound and nowhere near as bioactive. If a chitosan biofungicide is not soluble it will not be active on the leaf surface or absorbed by the plant cell.

Precipitate at high pH

Finally, a really good test for the presence of chitosan is to add a few drops of alkaline solutions (such as sodium hydroxide or potassium hydroxide) into the solution. If chitosan is present it will quickly precipitate out when the pH is raised above 7.0. No precipitation = no chitosan.

If your product passes all these tests, you can be confident that it contains chitosan. This is regardless of whether you are using the chitosan as a biofungicide, biostimulant, or even for non-agricultural purposes.

With our technical know-how here at Eutrema, we are able to manufacture the highest quality chitosan products, and can advise you on how to use chitosan products on your crops.

To purchase our 5% chitosan soluble concentrate, please visit:

Dr Russell Sharp

Eutrema Ltd

1 Comment

  • Paul Watson

    Hi Russel. I tried subscribe to your news letter but it didn’t go through. I wanted anyway to ask apication details and recommended dilutions and spray frequencies for different applications like downey mildew for grapes, botrytis on tomatoes anthracnose on chillis to name a few I have heard about from farmers. Perhaps black spot on citrus too… though perhaps you would not have encountered in the UK. Regards

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