Determination of Lactose in Lactose-Free and Low-Lactose Milk, Milk Products, and Products Containing Dairy Ingredients by the LactoSens®R Amperometry Method: First Action 2020.01

Background The AOAC Stakeholder Panel on Strategic Food Analytical Methods approved Standard Method Performance Requirements (SMPR®) 2018.009 for lactose in low-lactose or lactose-free milk, milk products, and products containing dairy ingredients. The LactoSens®R Method is a biosensor assay kit developed for the determination of lactose in a variety of lactose-free or low-lactose milk, dairy, and infant formula products produced with yeast-neutral lactases. Objective In response to a call for methods, the LactoSensR method was validated in a single laboratory study with comparison to SMPR 2018.009. Method The LactoSensR method was evaluated for calibration, interference, repeatability, recovery, and robustness. In a method comparison study samples naturally containing low levels of lactose were evaluated using LactoSensR and an accredited high-performance anion-exchange chromatography with pulsed amperometric detection. Results Calibration with lactose standard solutions was shown to be linear and the method was shown to be free of interference from a variety of sugars, vitamins, alcohols, flavorings, and other compounds. Matrix studies, including 85 spiked materials, 55 products naturally containing lactose, and 13 reference materials, resulted in RSDr of 0–10.5% at 8–100 mg lactose/100 g and 0.2–5.4% at >100 mg lactose/100 g for milk and dairy products and 1.0–6.8% for infant formula, in compliance with SMPR 2018.009 with few exceptions. Recovery was 85.0–110.3% at 8–100 mg lactose/100 g and 85.6–109.7% at >100 mg lactose/100 g for milk and dairy products and 91.1–97.0% for infant formula, also meeting the performance requirements with few exceptions. The method was shown to be robust to changes in ambient temperature, sample temperature, and sample volume. Conclusions The LactoSensR method compares favorably with the requirements of SMPR 2018.009 and should be adopted as a First Action AOAC Official MethodSM. Highlights The LactoSensR method is a fast, easy-to-use method that meets the requirements of SMPR 2018.009.