AOAC GFA Stakeholder Program Meeting Book (March 15, 2023)

4.1.3 Matrix / POD study A matrix/POD study must be performed in each claimed matrix. In order to ensure that each claimed gluten source is represented, the gluten sources must be rotated across the claimed matrices as shown in Tables 1 and 2. The single matrix in which all gluten sources are tested, listed in Tables 1 and 2 as Matrix 1, should be the most highly processed matrix used in the validation study.

Matrices Claimed

Matrices Claimed

Matrix

1

2

3

4

5

Matrix

1

2

3

4

5

Wheat Rye Barley

Wheat Rye Barley

Wheat Rye Barley

Wheat Rye Barley

Wheat Rye Barley

Wheat Rye Barley Oats

Wheat Rye Barley Oats

Wheat Rye Barley Oats

Wheat Rye Barley Oats

Wheat Rye Barley Oats

1

1

2 3 4 5

Wheat Wheat Wheat Wheat

Rye

Rye

Rye

2 3 4 5

Wheat Wheat Wheat Wheat

Barley Barley

Rye

Rye Rye Barley Barley

Wheat Table 1. Rotation of gluten sources across claimed matrices for methods claiming to detect wheat, rye and barley. The rotation of single gluten sources would continue for six matrices and greater.

Oats

Table 2. Rotation of gluten sources across claimed matrices for methods claiming to detect wheat, rye, barley and oats.

I find these tables very confusing. These should be modified - maybe a different header across the top? How do I use this table? Maybe give an example in the text? The current proposal of rotating matrixes and gluten sources does not deliver meaningful results. E.g. could different recoveries be the result of different gluten sources or different matrices. Suggestion: test all gluten sources in one matrix for every five claimed matrices / for every claimed matrix category. All other matrices will be tested either with the gluten source showing the highest CDC or with wheat (as wheat is by far the most important gluten source). The matrix chosen to test all claimed gluten sources should be one of the more challenging matrices (most highly processed). Differences between gluten sources will thus be tested in the first matrix, differences between matrices with wheat (or highest CDC cereal) in all other tests.

Table 1 and 2 are Confusing. Consider reformatting like this: