ISO 5548:1980

Caseins and caseinates — Determination of lactose content — Photometric method

Specifies a method for determining the lactose and other soluble carbohydrates content of caseins and caseinates containing less than 2.0 % of total soluble carbohydrates. Before precipitation of the casein with acetic acid and sodium acetate solution and subsequent filtration a test portion is dissolved either in hot water in the case of caseinates or in hot water with the addition of sodium hydrogen carbonate in the case of acid caseins or in hot water with the addition of pentasodium triphosphate in the case of rennet casein. The content of total soluble carbohydrates is expressed as anhydrous lactose as a percentage by mass.