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Enzymatic-gravimetric dietary fibre is the dried indigestible residue after enzymatic digestion, corrected by subtracting the ash and residual protein it contains. Without those corrections the figure is overstated, sometimes by 10-20% of the result on mineral-rich or high-protein samples.
Dietary fibre
Fibre % = (residue - ash in residue - protein in residue) x 100 / sample weight
Only if the method precipitates it with ethanol before filtration, as AOAC 991.43 does. Simpler crude fibre methods measure only lignin and cellulose and greatly understate total dietary fibre.
Crude fibre is an old feed-analysis method that dissolves most soluble fibre and hemicellulose. Dietary fibre for labelling must use an AOAC total dietary fibre method.