ISO 5498:1981 Preview
Agricultural food products -- Determination of crude fibre content -- General method
This standard was last reviewed and confirmed* in 2014.
*Therefore this version remains current
The method consists in boiling with sulphuric acid solution (after any necessary grinding and defatting), and separation and washing of the insoluble residue. Boiling this residue with sodium hydroxide solution, then separation, washing, drying and weighing of the insoluble residue, and determination of the loss in mass on incineration. An annex A specifies methods of extraction of fatty substances. An annex B gives various devices for the separation of crude fibre and supplementary information on the procedures for their use.