Determination of lactose in milk and milk-derived ingredients using biosensor-based techniques

Lactose is the primary solid constituent of bovine milk, accounting for 35% of the total solids in whole milk, and is the primary constituent of many dairy ingredients, such as whole milk powder (about 40% dry-basis lactose) or whey powder (about 70% dry-basis lactose). As a result, the properties of several dairy products, particularly concentrated and dehydrated products, are dominated by lactose properties such as solubility, crystallization behavior, mutarotation properties, and tendency to Maillard browning. Lactose assays commonly employed by the dairy industry are time-consuming and require sophisticated equipment or trained staff to perform. A blood glucose meter (BGM) biosensor can be applied as an approach for measuring lactose in milk and milk products, where after hydrolysis of lactose into glucose and galactose, the resulting glucose content can be measured with the BGM. For correlating the glucose reading with the lactose content in milk and milk products, a calibration curve must be developed between the known lactose concentration and BGM reading. The BGM method can be a promising tool for rapid, low-cost analysis of lactose in milk and milk products for purposes such as quality control, process development, or ingredient standardization. However, the type of milk and milk product, amount of lactose present, pH of medium, and amount and type of nonlactose interferents must be taken into consideration during standardization of BGM usage for lactose estimation.