There are test tube and skin tests to recognize allergy to foods like peanuts. Some people allergic to shrimp also react to crabs, lobster, and craw fish. Ragweed sensitive people can react to melon, banana, and celery. The melon and banana problems are usually limited to the mouth and throat. Rarely celery may cause anaphylaxis if eaten before exercise.
Food allergens have small molecular weights, which allows absorption through the lung or gut lining.
Food allergens in general are stable in normal digestive juices for 2 or more minutes but non-allergenic food proteins are destroyed in 30 seconds or less. The transfer of known allergens to bioengineered crops can be detected in the test-tube or in people. Certain laboratory tests will work. One can also skin test or use serum pooled from known allergic people. Double blind placebo controlled challenge of allergic people is generally not done for safety reasons.