This was determined as described by49 with little modification. A glass crucible containing 2 g of the sample and attached to the extraction unit, boiling 1.25% sulphuric acid and solution (150 ml) was then added. The sample was digested for 30 min, after which the acid was drained out, and boiling distilled water was used to rinse the residue four times. The residue was then rinsed using 100 ml of 1.25% NaOH solution. Finally, the crucible was removed from the extraction unit and oven-dried at 110 °C (Overnight), allowed to cool in a desiccator and weighed (W1). Ashing of the sample was then done in a muffle furnace at 550 °C for five hours cooled in a desiccator and reweighed (W2).

The percentage of crude fibre was calculated using the following formula: