AOAC ISPAM Stakeholder Panel Meeting Book 9-24-17

Suggested Methods for Estimating Gluten in Grain Samples Method of Wieser et al. using RP-HPLC after selective Osborne-like extraction. Katharina Scherf has been using this method to characterize grains. ƒ The method is well-established, but requires HPLC. We have tried water and NaCl extraction to remove soluble proteins (by definition non-gluten by Codex) followed by centrifugation, then Dumas nitrogen on the remaining pellet. ƒ Our results have been similar to the Wieser results. Gluten = Dumas N 2 *5.68 Similarly, we have tried extraction of non-gluten proteins with 0.4 M NaCl in PBS (pH=7.5) followed by Dumas nitrogen analysis of the resulting centrifuged pellet. Potentially, an approximation could be made on a sample just by a Dumas nitrogen and use a factor for each grain (e.g., for wheat, multiply protein by 0.8, for rye and barley, multiply protein by 0.55) based on Katharina Scherf’s empirical data. 2. 3. 4. 1.

SMPR

Parameter

Acceptance Criteria

Analytical Range (ppm)

” 5 to

LOD (ppm) LOQ (ppm)

” ”

Recovery (%) a

50 to 200 b

RSD r

Not Defined Yet

RSD R

Not Defined Yet