Salicin Discs are used to differentiate bacteria based on the salicin fermentation ability. Microorganisms can only ferment certain carbohydrates, depending on the enzymes they possess to break down carbohydrates. Fermentation can be detected by gas production (CO₂) in liquid media and/or color change of pH caused by acid production. The salicin discs are aseptically added to any sugar-free basal media to test the ability of the organism to hydrolyze salicin, an alcoholic β-glucoside, as the sole source of carbon and energy during fermentation. Salicin is typically fermented under acid and gas production by diverse Enterobacteriaceae but also other bacteria are able to ferment salicin.

Salicin Discs are recommended to detect salicin fermenting bacteria in food and environmental samples. They find their application in various sectors such as the food and dairy industry, water industry, pharmaceutical laboratory testing, cosmetic industry, environmental and sanitary testing, clinical diagnostic, etc.