The enzyme-linked immunosorbent assay — the full form of ELISA — is the laboratory workhorse that detects and measures substances using antibodies linked to enzymes. Antigen from the sample is captured by antibodies fixed to a plate; a second antibody, carrying an enzyme, binds to it; the enzyme then converts a substrate into a coloured product, and the colour’s intensity measures how much target was present. Food laboratories run ELISA for allergens — peanut, milk, gluten — for mycotoxins, for veterinary drug residues, and for pathogens, getting sensitive, specific answers in hours. The method’s power is the antibody’s specificity married to the enzyme’s amplification: a trace of target becomes a readable signal. Few analytical techniques have done more for food safety testing — ELISA put the modern allergen-control programme within every competent laboratory’s reach.