AOAC ERP Gluten Assays - Dec 2018

Annex B

Table 14. Summary of results obtained for oat-based cookies incurred with gluten from wheat or rye or barley; mean concentrations and standard deviations derived from all three lots.

mean mg/kg

SD

CV

recovery

mg/kg

(%)

(%)

Wheat gluten 11.5 mg/kg Rye gluten 11.5 mg/kg Barley gluten 11.5 mg/kg Wheat gluten 46 mg/kg Rye gluten 46 mg/kg Barley gluten 46 mg/kg

7.47 11.5 14.0 25.1 38.0 39.2

2.31 1.62 1.73 2.42 3.88 4.17

30.9 14.2 12.4

65%

100% 122%

9.7

55% 83% 85%

10.2 10.6

The porridge was produced as follows:

18 g grounded gluten-free oat flakes were mixed with 2 g oat flour that was contaminated at a level of 2000 mg/kg gluten from wheat or rye or barley. For each contaminating grain, 100 mL milk and 8 g of sugar were added and cooked in a Thermomix (Vorwerk, Wuppertal, Germany) for 5 min under constant stirring. The porridge was cooled down to room temperature under slow stirring. To correct for loss of water during cooking the amount of each porridge samples was determined after cooling down. The gluten content of these samples was 32 mg/kg. To produce samples with lower gluten contents from wheat, rye or barley, 19.5 g grounded gluten-free oat flakes were mixed with 0.5 g oat flour that was contaminated at a level of 2000 mg/kg gluten from wheat or rye or barley. For each contaminating grain, 100 mL milk and 8 g of sugar were added and cooked in a Thermomix for 5 min under constant stirring. The porridge was cooled down to room temperature under slow stirring. To correct for loss of water during cooking the amount of each porridge samples was determined after cooling down. The gluten content of these samples was 8 mg/kg. A blank porridge was also produced. Each sample was used within 24 h for gluten analysis to prevent any microbiological spoilage. Table 15 shows the results of the analysis of all gluten-containing porridge as well as for the blank porridge.

Table 15. Recovery experiment for oat-based porridge incurred with wheat or rye or barley at gluten levels of 8 mg/kg or 32 mg/kg; six extractions per lot and sample.

Lot 1

Lot 2

Lot 3

mg/kg gluten

Recovery

mg/kg gluten

Recovery

mg/kg gluten

Recovery

Blank

89% 72% 83%

79% 63% 71% 94% 93% 69% 97%

79% 63% 71% 94% 93% 69% 97%

Wheat gluten 8 mg/kg

105% 112%

75% 97%

118%

121% 107%

121% 107%

99% 92% 99%

Rye gluten 8 mg/kg

99%

99%

100% 121%

100% 121%

116%

Page 27 of 33

RIDASCREEN ® Total Gluten In-house validation report 2018-10-21