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Gluten Testing and Cleaning

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Posted 09 March 2022 - 07:33 PM

Hello everyone, 



I am a new member to this site although I have been following for a long time. I have seen great suggestions for different topics in this forum and I'm hoping to pick your brains on this situation as we have tried many things to no avail.

We are a bakery / co-packing facility and we produce mostly gluten containing products but have a couple gluten free SKUs which we don't make often. Most of the equipment is dedicated for GF products and some is shared. 

When we make these products, all of the equipment is thoroughly cleaned then swabbed before production.

We used rapid test swabs (have tried both Hygiena and Neogen) for the equipment then rapid tests for finished product throughout the run to validate. 


For some reason that we cannot figure out, we have started failing equipment swabs which has prevented us from producing. Sometimes we have to wash everything 4-5 times before we are able to get negative results. 


At first we thought we had defective tests, but we tried different brands and lots of tests, but keep getting the same results with everything. We also validated them by testing GF ingredients by themselves which came back negative.

Nothing has really changed in our operations or the way we perform sanitation, and we have no issue removing other allergens (we have egg, milk, sesame, soy, peanuts and tree nuts in the facility, and very rarely fail a test after sanitation with any of these).

We had some recommendations from the company that supplies our cleaning chemicals, but saw no improvement in the amount of failed tests after following them. 


Has anyone encountered any issues with gluten removal or testing? We have been trying to do research online but can't seem to find much. Our customers are getting so frustrated because we do not feel comfortable making the GF products. Any information will be greatly appreciated! 



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Posted 09 March 2022 - 10:22 PM

There are a number of possible reasons for this.  Unfortunately, without more information it is not possible to narrow down the issues.  It might be worth having someone from outside visit the facility to see if there is something happening with the equipment.  The problem could also be related to your ingredient supplies, including the possibility that your supplier/suppliers have problems that they don't know about. 


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Posted 10 March 2022 - 08:00 AM



If the repeated failures have only started recently at least one thing must have changed, could be any number of things i.e. change in cleaning method/equipment/chemicals/operatives/materials/hygiene or method of swabber/contamination introduced etc etc. Have you trended your swabbing data to see if you can identify any commonalities in the failed results? Regards tow the swabs themselves both are reputable brands and should be ok, I use vast numbers of Neogen gluten swabs myself for line release.


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Posted 10 March 2022 - 09:40 AM


Are you testing straight after applying a disinfectant? I'm wondering if there is cross reactivity with your tests and the chemicals used?

We found this with some swabs, they were still showing high positives despite an item being cleaned to within an inch of it's life. Determined it was residue chemical reacting with the test.  


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Posted 10 March 2022 - 06:31 PM

You could check the dishwasher/ 3-Compartment sink you using for washing.

Maybe there are some residues here that have given you problems?

The 10ppm threshold can be met by just one drop of allergen being diluted by 5 liters of water.


We had a simlar issue since 160-180°F water alone doesnt completely hydrolyze allergenic proteins.


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Posted 17 March 2022 - 02:18 PM

A while ago I had a customer who made both gluten-containing and gluten-free items, who started getting surface positives after cleaning. The culprit wound up being a stack of (laundered) rags that they were using as part of the cleaning process. The facility kept them on an open shelf on the production floor, so of course they were covered with a fine dusting of flour when the facility made gluten-containing items. Could something similar be going on with your facility?


If not, some info that would be helpful: Are you getting positives with both general protein swabs and also gluten-specific swabs? Are they appearing as high positives or weak positives? Are these positives happening across all of the surfaces or only certain ones (and if so, which ones)? Are you running gluten-containing products in another part of the facility at the same time (is there an issue of airborne dust)?

Emily Kaufman  
Emport, LLC
More safe food, more happy people

866.509.4482 • 718.717.2353
emilyk@emportllc.com • emportllc.com


Rick Reyes

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Posted 17 March 2022 - 02:27 PM

Just a simple suggestion, you might want to look at the equipment condition (age, wear) then look at the cleaning procedures. One thing that I may suggest is that your equipment cleaning include an acid cleaning step at least once a week to keep mineral build up from providing harborage for bacteria and allergens. I ran into this a few years ago. 

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