AOAC OMB Final Action Recommendation (December 2019)-2016.14

2016.14 (October 2019) – FOS-03 MANUSCRIPT

FOR ERP USE ONLY DO NOT DISTRIBUTE

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A.

Principle

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Samples are reconstituted in water (if required) and further diluted until the concentration

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of fructan in solution is such that after hydrolysis the fructose and glucose concentrations

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will be within the range covered by the standard curve. The diluted sample is treated with

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a mixture of sucrase and α-glucanases to hydrolyse sucrose and α -glucooligosaccharides

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to their constituent monosaccharides. The sample is passed through a solid phase extraction

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(SPE) column packed with graphitized carbon. Salts and monosaccharides pass through

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and are washed away, while the fructans are retained. Fructans are released from the

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column using an acetonitrile solution. The released fructans are hydrolysed with a

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fructanase mixture, and the released glucose and fructose are analysed by high performance

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anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD). The

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fructan content is calculated by summing the glucose and 0.9 × the fructose contents

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measured. In some matrices, a blank correction may be necessary and can be applied.

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B.

Apparatus and Materials

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(a) Analytical balance. —Readability of 0.1 mg.

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(b) pH-meter. —Readability of 0.1 pH.

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(c) Microtubes. —1.5-mL & 2-mL.

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(d) Floating rack for microtubes.

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(e) Water bath. —Able to maintain 80 °C ± 1 °C, with magnetic stirring if available.

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(f) Water bath. —Able to maintain 40 °C ± 1 °C.

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(g) Microcentrifuge. —Able to operate at 10 000 x g .

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(h) Micropipettes. —With tips (0.1 to 1) mL.

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(i) Vortex mixer .

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(j) Single-use plastic pipettes. —Graduated, 2-mL, 10-mL and 25-mL.

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(k) Single-use syringes. —2-mL.

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(l) Graphitized carbon solid phase extraction (SPE) columns. —100 mg.

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