A sensitive, high-throughput fluorescent method for the determination of lactoperoxidase activities in milk and comparison in human, bovine, goat and camel milk

•A sensitive microplate fluorescent assay was developed for milk peroxidase activity.•Adding excess exogenous thiocyanate enabled milk normalisation and enzyme activation.•High assay sensitivity and reproducibility was demonstrated.•Lactoperoxidase activities in milk from four species were comprehensively analysed.•A hydrogen/oxygen transfer-based mechanism for LPO in the assay system was proposed.