2.4. Determination of Dietary Fibers

Dietary fibers were determined according to gravimetric AOAC method 991.43 [14]. Samples were treated with thermostable α-amylase, protease and amyloglucosidase (Megazyme Total Dietary Fiber Assay Kit, Megazyme Ltd., Bray, Ireland). The share of insoluble dietary fibers (IDF, %) was determined gravimetrically after filtration, and soluble dietary fibers (SDF, %) were determined by precipitation from the obtained filtrate. After correction for undigested protein (Kjeldahl method) and ash (mineralization at 525 °C), total dietary fibers were calculated Equations (2) and (3) as a sum of IDF and SDF. The values were calculated on the dry matter of the sample.

where: R₁ = residue weight 1 from m₁; R₂ = residue weight 2 from m₂; m₁ = sample weight 1; m₂ = sample weight 2; A = ash weight from R₁; P = protein weight from R₂; B = blank; BR = blank residue; BP = blank protein from BR₁; BA = blank ash from BR₂.