Accurate analysis of residual lactose in low-lactose milk: Comparing a variety of analytical techniques

To receive the designation "lactose-free", milk should contain <0.01% (w/w) lactose. As the analysis of such low levels of lactose is often hampered by other saccharides present or formed during milk processing, methods are required that are highly sensitive, accurate and precise. Currently, there is no international standard analysis method for the determination of lactose in low- or lactose-free milk, despite such a need from the dairy industry. We validated the analysis of residual lactose in lactase-treated UHT milk using HPAEC-PAD on a CarboPac PA100 column and compared it with a variety of commonly used analytical techniques for measuring lactose, including HPLC-RI, NMR, enzymatic kits, cryoscopy, and lactose biosensors. The results show that only one analytical technique, namely the Biomilk(300), an amperometric biosensor, has performance comparable with analysis by HPAEC-PAD, which remains one of the most accurate, precise and sensitive methods to assess low levels of lactose in milk. (C) 2019 The Authors. Published by Elsevier Ltd.