A Single-Enzyme Electrochemical Biosensor for Lactose Detection in Human Breastmilk and Dairy Products

Lactose, a disaccharide found predominantly in human breast milk and dairy products, plays a vital role in human health and nutrition. While lactose is an essential energy source particularly for infant growth, it is also a biomarker of low milk production in breastfeeding women. Furthermore, lactose intolerance affects a substantial portion of the global population, impacting the quality of life. Therefore, the ability to detect and quantify lactose is important as a biomarker for both milk production and nutritional content. Here, we report on the development of a single-enzyme electrochemical biosensor for lactose employing lactose oxidase (LOx), which converts lactose to lactobionic acid and hydrogen peroxide. The sensor showed high specificity, achieving a limit of detection of 1.4 μM. The analytical performance of the sensor was verified in human breast milk as well as bovine milk. This approach allows for a rapid, reliable, and potentially portable platform for lactose detection, making it ideal for both clinical applications and routine controls in the food industry.