Determination of Total, Soluble, and Insoluble Dietary Fiber in Foods—Enzymatic-Gravimetric Method, MES-TRIS Buffer: Collaborative Study

Abstract

A joint AOAC/AACC (American Association of Cereal Chemists) collaborative study of methods for the determination of soluble, insoluble, and total dietary fiber (SDF, IDF, and TDF) was conducted with 11 participating laboratories. The assay Is based on a modification of the AOAC TDF method 985.29 and the SDF/IDF method collaboratively studied recently by AOAC. The principles of the method are the same as those for the AOAC dietary fiber methods 985.29 and 991.42, Including the use of the same 3 enzymes (heat-stable α-amylase, protease, and amyloglucosldase) and similar enzyme Incubation conditions. In the modification, minor changes have been made to reduce analysis time and to Improve assay precision: (1) MES-TRIS buffer replaces phosphate buffer; (2) one pH adjustment step Is eliminated; and (3) total volumes of reaction mixture and filtration are reduced. Eleven collaborators were sent 20 analytical samples (4 cereal and grain products, 3 fruits, and 3 vegetables) for duplicate blind analysis. The SDF, IDF, and TDF content of the foods tested ranged from 0.53 to 7.17, 0.59 to 60.53, and 1.12 to 67.56 g/100 g, respectively. The respective average RSDR values for SDF, IDF, and TDF determinations by direct measurements were 13.1, 5.2, and 4.5%. The TDF values calculated by summing SDF and IDF were in excellent agreement with the TDF values measured independently. The modification did not alter the method performance with regard to mean dietary fiber values, yet It generated lower assay variability compared with the unmodified methods. The method for SDF, IDF, and TDF (by summing SDF and IDF) has been adopted first action by AOAC International.

Chemical composition, sensory and cooking quality evaluation of durum wheat spaghetti enriched with pea flour

“…Protein content (% N 9 5.7) was analysed using the micro-Kjeldahl method according to AACC method 46-13 (2000). Total dietary fibre (TDF), soluble water dietary fibre (SDF) and insoluble water dietary fibre (IDF) contents were determined by means of the Total Dietary Fibre Kit (Megazyme International Ireland Ltd., Wicklow, Ireland) based on the method of Lee et al (1992). The available carbohydrates (ACH) were determined according to the method of McCleary & Rossiter (2006) as described in the ACH assay kit (Megazyme).…”

Bioactive compounds, in vitro antioxidant capacity and Maillard reaction products of raw, boiled and fried garlic (Allium sativum L.)

“…Total, soluble and insoluble fibres were analysed in samples as described by Lee & Prosky (1992). The results are reported as g per 100 g (dry matter).…”

Use of berry pomace to replace flour, fat or sugar in cakes

“…This can be attributed to the water binding capacity that was higher for aronia pomace (3.85 g g À1 dry matter) than for black currant pomace (3.20 g g À1 dry matter, determined according to Zahn et al, 2013). Differences in water binding capacity can, in turn, most likely be ascribed to the differences in soluble fibre content of both pomaces (39.7 g kg À1 and 70.4 g kg À1 for black currant and aronia pomace, analysed using the total dietary fibre kit (Megazyme u.c., Bray, Ireland) based on AOAC 991.43 according to Lee et al, 1992). Differences in apparent viscosity between the samples became less pronounced with increasing shear rate.…”