The liquid food products are one of the most important sources of energy for humans, so contamination of these products with Listeria, especially Listeria monocytogenes, can pose a life-threatening hazard to many people. Listeria monocytogenes, a foodborne bacterium, is thought to be a serious cause of disease in humans and animals. The detection and enumeration of microorganisms in food are an essential part of any quality control or food safety plan. Traditional culture methods for detecting microorganisms in food are based on the growth of the microorganisms in different culture media like pre-enrichment, selective enrichment, selective plating, and identification. Traditional microbial identification processes rely on phenotypic analysis. Morphology patterns, staining, and biochemical tests are common and less costly methods scientists use to distinguish an organism’s identity. Advances in technology have made detection and identification faster, more sensitive, more specific, and more convenient than traditional assays.