The beta-glucan (mixed-linkage) kit (K-BGLU) should work with this sample type.
Samples will need to be freeze-dried prior to the analysis. It may be required to wash these samples with aqueous ethanol as described for malt samples, please see page 12 of the data booklet) to remove low molecular weight compounds that may interfere.
As these samples have not been tested by Megazyme, this would have to be internally validated.