Polyacrylamide gel electrophoresis

Electrophoresis run through a polyacrylamide gel serving as the diffusion medium, separating proteins by size as they migrate through the gel matrix under an electric field. Food analysts use it to fingerprint the proteins of milk, meat, fish, and cereals, verifying species authenticity, detecting undeclared ingredients or adulteration, and checking the purity of enzyme preparations. Because the band pattern reflects the protein composition so precisely, the technique is a workhorse of food authenticity testing and allergen investigation. Modern variants and mass spectrometry have extended its power, but the classic gel remains a staple of food protein laboratories.