Polymerase Chain Reaction (PCR) is a molecular technique that can amplify small amounts of DNA to millions of copies. It involves denaturing DNA, annealing primers to the DNA, and extending the primers to exponentially replicate the target DNA. PCR is useful for detecting pathogens in foods as it is sensitive, specific, convenient, and provides results faster than conventional methods. A typical PCR analysis involves enriching a food sample, extracting DNA from the sample, and amplifying and analyzing the DNA to detect any pathogens present.