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Your company may be asked to respond to reports from consumers of positive gluten results in your product, coming from home testing devices. Often these home testing devices are not on GFCO’s list of approved kits, and we think it’s important that manufacturers understand why, so they can respond to related consumer complaints.
Although some home devices make claims that the method has undergone a peer-reviewed validation, the studies they have done often do not include a sufficient number of different food types, and typically do not test a suitable number of replicates in each food type to accurately assess their performance. Additionally, these studies often use gluten spiked into a food after it is prepared, rather than introducing gluten prior to any heating or processing, so there is no information on how the method performs in cooked or processed samples. Data analysis in these studies may calculate sensitivity and specificity numbers from across all food types, rather than the more acceptable practice of reporting them per food type. And their data typically does not include the commonly accepted components of a validation such as a thorough interference study, a robustness study, a hook effect study, or a product consistency and stability study.
GFCO recommends that all positive results from rapid test kits be confirmed using an appropriate quantitative ELISA method, and this is especially true when the initial positive result came from a home test kit. If you receive a report of a positive result from a consumer, ask them if they have any of the remaining sample that they can send to you, and send it to a laboratory for testing. Whether or not the consumer has any sample remaining, pull your retain sample from that lot and send it for testing. Have multiple separate tests performed on each sample, as this will help you to put together a complete picture of the potential gluten content of your product.
GFCO receives regular reports of positive test results from home test kits being used on certified products, and a > 10 ppm result has only been confirmed in one instance in the past seven years. Receiving this type of report from consumers should be viewed as an opportunity to investigate, and to demonstrate your product’s safety. And in the unlikely event that the positive result is confirmed, it’s in everyone’s best interest to know about contaminated product and remove it from sale.
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