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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(g) Carrez I solution .—Dissolve 10.6 g potassium hexacyanoferrate(II)trihydrate in 100 mL

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water and store in a brown bottle. Stable for 6 months at room temperature. [NB: Optional

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reagent].

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(h) Carrez II solution .—In a 100-mL volumetric flask, dissolve 22.0 g zinc acetate in 90 mL

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water and add 2.9 mL glacial acetic acid. Make up to the mark with water and homogenize.

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Stable for 6 months at room temperature. [NB: Optional reagent].

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(i) Sodium azide solution (0.5 %).— Dissolve 1 g sodium azide in 200 mL of water [NB:

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Optional].

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(j) Sucrase/β-amylase/pullulanase/maltase solution .—Dissolve the content of the bottle

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containing freeze-dried powdered sucrase, β-amylase, pullulanase and maltase C(q) in

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22.0 mL sodium maleate buffer D(b) . Mix well and divide into aliquots of 2 mL each and

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store frozen at -20 °C in polypropylene tubes until use. Stable for 5 years at -20 °C. NOTE:

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For the development and validation of this method, the pre-prepared enzyme mixture

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available in the Megazyme kit K-FRUC, was used. When enzymes from another source are

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used, the buffer composition (type, concentration and pH) may need to be adapted to the

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recommendations of the supplier. It is also imperative to ensure the enzyme mixture will

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completely hydrolyse any sucrose in the product without hydrolysing the fructans. This can

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be checked by performing an analysis with sucrose as an analyte and with a pure fructan as

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an analyte. No fructan should be measured when sucrose is analysed, and more than 90 %

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recovery should be achieved when a fructan of known purity is analysed (recommended to

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check using both long chain inulin and short chain FOS). An alternative test for checking

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the suitability and performance of the enzyme mixture is described in Appendix A.

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(k) Fructanase (exo-/endo-inulinases/endo-levanase) solution .—Dissolve the content of the

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bottle containing freeze-dried powdered exo- and endo-inulinases and endo-levanase C(r)

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in 22.0 mL sodium acetate buffer D(c) . Mix well and divide into aliquots of 2 mL each and

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store frozen at -20 °C in polypropylene tubes until use. Stable for 5 years at -20 °C. NOTE:

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