Blotting

Blotting moves nucleic acids and/or proteins — directly or off a gel — onto a chemically reactive matrix such as nitrocellulose, where they bind covalently in the same pattern as on the original gel. Targets are then detected with complementary labelled nucleic acids or antibodies, and the family includes Northern blotting for RNA, Southern blotting for DNA, and Western blotting for proteins. In food analysis these techniques verify species identity, detect pathogens and allergens, and confirm genetically modified traits. Though increasingly complemented by PCR and sequencing, blotting remains a reference method where visualised, size-resolved confirmation is required.