Food Allergy and Allergen Testing

Food Allergy and Allergen Testing

What are allergens?

Food allergens can be defined as usually harmless food components or constituents which induce an allergic reaction in a sensitised individual. Food allergies affect about 1-2% of adults and 5-8% of children in the UK according to the FSA. Food allergy should not be confused with food intolerances such as lactose intolerance which is due to an inability to digest lactose or food poisoning from microbial contamination of food. The symptoms may be similar but the underlying causes are often different.

Symptoms with varying degrees of severity include itchy or swollen lips, mouth, tongue and throat; skin reactions; wheezing or shortness of breath; diarrhoea, feeling sick, vomiting and bloating; coughing; a runny nose and sore, red and itchy eyes.

Over 160 foods/ingredients that cause allergies have been identified. These include:

  • Celery (including celeriac)
  • Cereals containing gluten (wheat, rye, barley, spelt, kamut or their hybridized strains).
  • Crustaceans (e.g. lobster, crab, crayfish, prawns and langoustine)
  • Eggs
  • Fish
  • Lupin (including lupin seeds and flour and which can be found in types of bread, pastries and pasta) 
  • Milk
  • Molluscs (such as clams, mussels, whelks, oysters, snails and squid)
  • Mustard
  • Nuts (Almonds, Hazelnuts, Walnuts, Cashews, Pecan nuts, Brazil nuts, Pistachio nuts, Macadamia nuts)
  • Peanuts 
  • Sesame
  • Soy beans (soya)
  • Sulphur Dioxide/Sulphites where added and at a low level above 10mg/kg in the finished product. This can be used as a preservative in dried fruit.

Labelling & Legislation

For the allergic consumer it is particularly important to have full information about potential allergens contained in food products. Manufacturers must follow the Food Information for Consumers Regulation (EU1169/2011). The regulation, which was published in October 2011, outlines allergen labelling provisions for pre-packed foods and introduced a new requirement for allergen information to be provided for foods sold non-packed or pre-packed for direct sales. In turn, this has led to greater consistency from food manufacturers in the way that allergen information is labelled on food products, making it easier for the consumer to find and understand. Additional information is also provided by the Food Standards Agency at www.food.gov.uk.

Testing for the presence of allergens as part of an effective quality control process allows manufacturers to safeguard against undeclared allergens entering final products, thereby enabling them to comply with current labeling requirements.

Allergen Testing

ALS offers a wide range of in-house and partner laboratory allergen testing, providing extensive support to the food manufacturing industry, thereby enabling them to deliver the product assurance the marketplace demands.

Two types of testing are available:

Automated ELISA (Enzyme Linked Immunosorbent Assay)

ELISA techniques use antibodies to selectively target allergens or specific marker proteins within a food product for detection. Once the allergen has been selectively bound by the antibody an enzyme linked to these causes a proportional colour change. This change can be measured to give highly sensitive results. The technique is applicable to multiple sample matrices including environmental swabs. The advantages of this technique include:

  • The test is highly specific for the analyte.
  • The test is highly sensitive for the analyte.
  • The technique is more environmentally friendly as it does not produce large volumes of waste solvents.
  • Relatively rapid detection technique

PCR (Polymerase Chain Reaction)

PCR techniques involve the extraction and amplification of target allergen DNA from samples. This test is highly specific but may not be representative of the quantity of allergenic protein content of a sample. This technique is highly useful when allergenic proteins are difficult to detect by ELISA. 

Real Time PCR is a variation using a thermocylcer to generate specific target species DNA copies, with each copy containing a fluorescent marker. These can be read by a spectrophotometer in real time where the signal generated by the fluorescent markers is directly proportional to the number of copies of the DNA (amplicons).

Additional testing is available using traditional chemistry techniques for sulphites (as sulphur dioxide) and histamine (by HPLC).

Allergen Test Methods

  • Almond
  • Celery
  • Crustacean
  • Fish speciation
  • Gluten
  • Egg
  • Meat speciation using ELISA or RT-PCR
  • Milk (Betalactoglobulin and Casein)
  • Mollusc
  • Next generation DNA sequencing
  • 9-Nut screen (Almond, Brazil, Cashew, Hazelnut, Macadamia (Queensland nut), Peanut, Pecan, Pistachio)
  • Peanut
  • Sesame
  • Soya

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