AOAC GFA Working Group Documents for Review (November 2022)

Document Comments with Responses

5 matrices, you could do this for the first three, but would then need to do all sources at all levels in the other two. So it gets complicated: MATRIX 1 MATRIX 2 MATRIX 3 Blank -- -- -- 0.5 CDC Wheat Rye Barley CDC Rye Barley Wheat 1.5-2x CDC Barley Wheat Rye o Another suggestion that has been made in the comments is to test all gluten sources in one matrix, and only one gluten source in any others. o Other suggestions would be appreciated, if we want to consider this.

4.1.3 second paragraph “Samples under each type of processing must be incurred” • One Sample

o Consensus from the group was that all processed samples in the matrix studies must be incurred

4.1.3 second paragraph “and in each case gluten would need to be added “ • 1 gluten source or all 4 gluten sources?

o See reply above under 4.1.3 second paragraph “A matrix/POD study must be performed for each claimed gluten source in each claimed matrix. “

4.1.3 page 8, second paragraph “For each gluten source-matrix combination” • For one matrix, the method developer must test all claimed gluten sources. For all others the method developer is required to test one gluten source per matrix. o This is another option to what I have suggested above under 4.1.3 second paragraph “A matrix/POD study must be performed for each claimed gluten source in each claimed matrix. “, and should also be reviewed by the group. 4.1.3 Page 8, second paragraph “sample at two times the highest cdc” • Is 2x the highest CDC required? What if CDC is higher than expected? E.g. test at 0, 0.5, 1 & 2. Predict your CDC will be 1, but results are 100% at 2 and fractional at 1. Do you need to add a sample at 4 ppm? o If you predict a CDC of 1, but your 1 ppm samples don’t give a POD of at least 0.95, then you would be adjusting your CDC to 2 and repeating the validation (although you wouldn’t have to repeat the levels you already did). So yes, that would mean the addition of a sample at 3 ppm or more, since the wording was changed to make the highest sample “at least 1.5x the CDC”. 4.1.3 Page 8, second paragraph “an additional sample must be prepared and analyzed with a concentration midway between” • How would you do this if the samples have to be blind coded or do you have to repeat the entire matrix study with the new concentration?