AOAC OMB Final Action Recommendation (December 2019)-2016.14

2016.14 (October 2019) – FOS-03 METHOD

FOR ERP USE ONLY DO NOT DISTRIBUTE

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FRUC, was used. When enzymes from another source are used, the buffer composition (type,

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concentration and pH) may need to be adapted to the recommendations of the supplier. It is also

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imperative to ensure the enzyme mixture will completely hydrolyse any sucrose in the product

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without hydrolysing the fructans. This can be checked by performing an analysis with sucrose as

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an analyte and with a pure fructan as an analyte. No fructan should be measured when sucrose is

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analysed, and more than 90 % recovery should be achieved when a fructan of known purity is

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analysed (recommended to check using both long chain inulin and short chain FOS). An alternative

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test for checking the suitability and performance of the enzyme mixture is described in Appendix

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A.

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

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containing freeze-dried powdered exo- and endo-inulinases and endo-levanase C(r) in 22.0 mL

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sodium acetate buffer D(c) . Mix well and divide into aliquots of 2 mL each and store frozen at -

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20 °C in polypropylene tubes until use. Stable for 5 years at -20 °C. NOTE: For the development

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and validation of this method, the pre-prepared enzyme mixture available in the Megazyme kit K-

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FRUC, was used. When enzymes from another source are used, buffer composition (type,

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concentration and pH) may need to be adapted to the recommendations of the supplier. It is also

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imperative to ensure the enzyme mixture will completely hydrolyse the fructan without

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hydrolysing any other glucose or fructose containing oligo- or polysaccharide that may be present

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after treatment with the sucrase mixture above. This can be checked by performing an analysis

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with a pure fructan as an analyte. More than 90 % recovery should be achieved when a fructan of

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known purity is measured.

(l) Wash solution for graphitized carbon SPE column (TFA 0.1 % in acetonitrile 80 % (v/v)) .—Into a

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100-mL volumetric flask, add 80 mL acetonitrile and 100 μL TFA. Make up to the mark with water.

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Stable for 6 months at room temperature.

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