Investigation of concentration of thiocyanate ion in raw cow’s milk from China, New Zealand and the Netherlands

•A survey of thiocyanate levels in raw cow milk across 3 countries over 1 year.•Able to propose a confident limit for natural thiocyanate in milk of 9 mg/kg.•Differences found between countries, provinces & seasons, but not farm scale.•Suggest that feed type is the main source of variation in thiocyanate levels found.

Thiocyanate ion is a natural component of cow’s milk (hereinafter as milk) which may be artificially augmented to activate the lactoperoxidase milk preservation system. This study presents a survey of thiocyanate levels in raw milk and proposes a naturally occurring baseline concentration of thiocyanate in milk, which is the basis for market supervision. 1669 raw milk samples from China, 270 samples from New Zealand and 120 from the Netherlands were collected in the survey. 65% of the samples contained thiocyanate above the detection limit. The average concentration of thiocyanate was 2.11 mg/kg (0.10–16.20 mg/kg). Differences in the concentrations of thiocyanate were found among three countries, the 12 selected provinces in China, and between summer and winter. The baseline concentration of thiocyanate found in raw cow’s milk was statistically calculated and rounded to 9.0 mg/kg. Thiocyanate in milk at this level does not present a food safety concern.