AOAC Official Method 992.16 Total Dietary Fiber Enzymatic–Gravimetric Method

First Ac tion 1992
Fi nal Ac tion 1997

(Applica ble to deter mination of total dietary fiber increals,beans, vegetables, and fruits.)
Results of the interlaboratory study sup porting ac ceptance of themethod (dry weight basis):
Turnip, 20.71%: sr = 1.01; sR = 1.37; RSDr = 4.85%; RSDR =6.60%
Wheat bran, 46.30%: sr = 0.69; sR = 1.91; RSDr = 1.48%; RSDR =4.13%
Bean, 18.19%: sr = 0.90; sR = 2.06; RSDr = 4.93%; RSDR =11.30%
Rice, 1.21%: sr = 0.18; sR = 0.22; RSDr = 14.73%; RSDR = 17.94%
Whole wheat bread, 10.29%: sr = 0.74; sR = 0.80; RSDr = 7.18%;
RSDR = 7.81%

A. Prin ci ple
Foods, dried and ground, are fat ex tracted if con tain ing >5% fat. A test por tion is treated in au to clave with heatstable amylase,amyloglucosidase, and pro te ase to re move starch and pro tein.Enzymatically undigested fiber is precipitated by ethanol and filtered. Resi due is dried, weighed, ashed, and reweighed. A second test portion is refluxed with neutral detergent and treated with a-amylase from por cinepan creas to remove water solublecar bohydrates and protein. Residue is dried, weighed, ashed, and reweighed. Total dietary fiber is calculated as sum of the 2 residues.