Food allergen testing: techniques and challenges

Allergens are a big concern for food manufacturers, with customer safety and organisational reputation on the line. But with so many allergens to test for where is the best place to start?


Food safety and quality consultants Leyla Collins and Barbara Hirst look at which techniques are available and how to match the right technique to the task at hand. Find out more about our allergen services here.


Video transcript



Hi, welcome to our video blog by RSSL.  I'm Layla Collins,


and I'm Barbara Hirst,


and we're Food Safety Consultants here at Reading Scientific Services Limited and we're going to be talking to you about food allergen testing and some techniques used and the challenges that we see.


So food allergens are proteins and unfortunately they can cause adverse reactions in some sensitive individuals which can result in fatal reactions now food allergen testing can be a key aspect of food safety but there are lots of different types of analytical methods out there.


Now Barbara, when we're testing for food allergens as I mentioned there's lots of tests out there there's ELISA, PCR, LC-MS-MS, so what should people be using when they're looking for food allergens? 


It's a really good question Leyla and I guess it depends on what the allergen is that you're actually interested in. I mean you mentioned earlier that food allergens are protein so ideally you want to be using a protein based technique such as ELISA that's probably the most commonly used one and that's based as I say on an antibody antigen interaction that's detecting the food protein so that's probably the best one you can choose. If you don't have an Elisa test for the specific allergen that you're interested in and for example celery there aren't any ELISA tests out there available so then you would be using most likely a PCR based method because that's detecting the DNA.


Now you briefly mentioned LC-MS-MS and that's probably the newest type of method that we have out there.


It is a protein-based method but it's probably more in the research area so not commonly used If you're interested in things like lactose you're likely to have to use a chromatographic method or if you're interested in sulfites of course which isn't a protein it's a chemical you're going to be using some kind of distillation technique so we're already making this sound quite complicated aren't we. So Leyla talk to us a little bit about how would you go about trying to choose a good laboratory to work with if you need to have some allergen testing done. Well yeah that's key is working with a good laboratory to help you navigate all of these problems 


So things like picking a lab that has an accreditation to an ISO standard so in this case 17025 now typically in the UK that's going to be UKAS but there are lots of different ones out there So picking one that has that accreditation is a really good start and you want one that you have a good communication with so one where you'll be able to talk to them about what your problems are what your contaminants are and you know help them helping you with your sampling plan and choosing the right test for what you're looking for and the question you want to answer. So really one that can guide you and you also want one with a good knowledge about what's going on in the industry and what cross-reactivities and other issues there are out there so thinking about cross-reactivities maybe you could explain a little bit about that Barbara.  
Yeah sure and it's a real common thing that we see isn't it that sometimes cross-reactivity isn't considered enough and when we're thinking about what does that mean basically it's when the test misidentifies something and gives you a false positive result and I think that probably the most common one I see out there is all of the ELISA tests for mustard they all of them cross-react with rapeseed so you'd get a you'd get a positive result but it might be because of mustard or it might be because of rapeseed and you need to figure out what happens there. So in RSSL for example we don't use the Elisa test we must we use a PCR test to try and mitigate that kind of risk but it's something just to be aware of but that's where partnering with a good lab will help you with some of that. And, I guess I'm thinking now Leyla the other thing that we hear a lot about is this spike recovery, can you tell us what that is please?


Yeah so that's another key kind of extra bit of validation that needs to be done when you're using these biological tests because unfortunately food is really complex and it can create lots of different interferences with the tests that you use.


So having a spike recovery basically means that the laboratory you're adding a small amount, or a small quantity, of the allergen a known amount that they measure and put into your sample run it through the analysis and see how much they get back out so if you put in 5 PPM of milk and you're looking for milk you hopefully are going to get 5 PPM back out and you know if that does happen that means that the test is suitable for your sample type however that's not always the case and sometimes you'll get more out like 20 PPM and that's creating a false positive result because something in that food is interfering with the test and causing that positive reaction.


And then it can also happen the other way and you might only get two PPM out and that's a false negative result so having that little bit of extra validation to show that actually your ingredients in your sample don't interact with the test and it is suitable.


So that's two types of different kind of issues that might arise with these biological tests and a third one thinking about it is positive control, so what would you say about that Barbara?


Do you know that's an area that we don't see that's commonly actually offered by laboratories and it's such an important element so if I think in the context of like cleaning validation.


So you've made a product that contains the allergen you're then going to clean in the factory and then you're going to make the product that doesn't contain it. Really important exercise is to check that the testing method that the laboratory has chosen can actually detect the allergen in the product that contains it so that's your positive control test and that's just a measure as to whether the laboratory have picked the right method is the test good enough can you detect roughly what you expect to be they're at least at a nominal level.


Gosh, I feel like Layla we've tried to cover so much in such a short area of time and um I guess if you are interested in in analytical testing for allergens at all at RSSL we have a very comprehensive service that we can help you out with pretty much all of the allergens that you might need to be testing for.


My colleague Layla actually she's written a very comprehensive article and we've just scratched the surface in this video blog and she's written an article about trying to choose the right testing laboratory and we also have an open course which you might be interested in coming along to and if you are that's all around sampling and analysis and it's got some really good interactive pieces so just go to our website and you'll be able to follow the links for that but just to say thanks very much for joining us on this and hopefully we'll see you again soon thanks now bye-bye.


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