AOAC OMB Final Action Recommendation (December 2019)-2016.14

2016.14 (Jan. 2019) FOS-03 MLT Report FOR ERP USE ONLY DO NOT DISTRIBUTE

Table 2016.14B. Scheme for sample dilution depending on expected fructan content Expected fructan content, g/100 g Dilution Dilution factor, D Powder Ready-to-feed Volume of Solution A, mL Final Volume, mL 0.2 – 4.0 0.03 – 0.45 No dilution No dilution 1 2.5 - 45 0.3 – 4.5 5 50 10 25 - 100 3.0 - 45 0.5 50 100 (e) Hydrolysis of sucrose and α-glucans.— Transfer 200 µL Solution B H(d) into a 1.5-mL microtube, add 100 µL of N,N’ -diacetylchitobiose internal standard solution D(d) and 200 µL of the sucrase/amylase/pullulanase/maltase enzyme mixture D(j) . Mix well (vortex), place the microtubes on a floating rack and incubate at 40 °C for 90 min. Cool down to room temperature. NOTE: Adapt these conditions according to enzyme manufacturer recommendations. (f) Optional Carrez Clarification .—(Skip if not necessary) Add 10 µL Carrez I solution D(g) to the sample and mix well. Then add 10 µL Carrez II solution D(h) and mix again. Centrifuge at 10 000 x g for 10 min and use the supernatant for the next step H(g) . (g) Removal of monosaccharides.— Prepare the graphitized carbon SPE columns B(l) , as follows: a. Flush with 3 × 400 µL SPE wash solution D(l) . b. Flush with 3 × 400 µL water. Then perform the following steps under gravity if possible (i.e without applying vacuum or positive pressure). However, depending on the SPE columns brand, a slight positive pressure may be necessary and can be applied): c. Apply 400 µL of the enzyme treated solution H(e) or H(f) . d. Wash with 2 × 1000 µL sodium chloride solution D(m) . e. Wash with 4 × 1000 µL water. f. Elute the fructans into a 2-mL microtube using 4 × 400 µL of SPE elute solution D(n) . g. Apply a little positive pressure to eliminate all solution from the column. h. Mix eluates from the SPE column well (vortex). (h) Hydrolysis of Fructans.— Transfer 700 µL of the eluate from the SPE column H(g) into a 1.5-mL microtube (marked “Sample”), add 200 µL of sodium acetate buffer D(c) and 100 µL of the fructanase enzyme mixture D(k) . Into a second microtube (marked “Blank”) transfer 700 µL of the eluate H(g) and add 300 µL of sodium acetate buffer D(c) . (NB: The “Blank” is necessary only for some matrices containing low amounts of fructans and may be skipped if it has already been established that it is not needed for a given matrix). For all tubes, mix well (vortex) and incubate at 40 °C for 40 min. After cooling, centrifuge at 10 000 × g for 5 min and then transfer 700 µL of the supernatant into a vial suitable for the instrument autosampler. NOTE: Adapt these conditions according to the enzyme manufacturer recommendations.