Plate Count Agar (PCA) is a microbiological growth medium commonly used to evaluate or monitor the "total" or viable bacterial growth of a sample. This non-selective medium is used in food bacteriology for the enumeration of aerobic bacteria in milk, meat, meat products, other food products, as well as the analysis of pharmaceuticals, cosmetics and their raw materials. The amount of bacteria is expressed in colony-forming units per gram (CFU/g) in solid samples and per ml (CFU/ml) in liquid samples. The composition of the medium may vary from one manufacturer to another, but it always contains peptone, yeast extract, glucose and agar. The medium contains an enzymatic digestion product of casein which provides amino acids, nitrogen, carbon, vitamins and minerals for body growth. The yeast extract mainly provides the B-complex vitamins.  Glucose is the fermentable carbohydrate and provides a source of energy for bacterial growth.  Agar is the solidifying agent.