Abstract: [Objective] The aims of this study were to assess the content, distribution and influencing factors of endogenous thiocyanate in raw dairy milk in New Zealand, and to provide references for risk evaluation and limit standard establishment of thiocyanate residue in raw dairy milk. [Method] From August 2022 to May 2023, a total of 800 raw milk samples were monthly collected from 50 dairy farms in South Island, New Zealand （no samples were collected in June and July due to the dry milk period of local dairy cows）. The contents of thiocyanate in raw milk samples were determined by using ion chromatography. The detection rate was calculated and the distribution of detection result was characterized. The influence of different sampling months and pastures on endogenous thiocyanate levels in raw milk was analyzed. [Result] A total of 798 raw milk samples were positive for thiocyanate, with an overall detection rate of 99.75%. The contents of thiocyanate in the tested samples ranged from 0 to 10.62 mg/kg, and the mean and median were 6.25 mg/kg and 6.21 mg/kg, respectively. The samples containing 0-2.00 mg/kg, 4.00-6.00 mg/kg and 6.00-8.00 mg/kg of thiocyanate accounted for 1.13%, 36.62% and 50.50% of all the tested samples, respectively, while the samples with thiocyanate content exceeded 10.00 mg/kg only accounted for 0.75%. The contents of thiocyanate in the samples collected from September to November 2022 increased monthly, and the contents of thiocyanate in the samples collected from December 2022 to May 2023 generally exhibited an increasing trend month by month. The samples collected from January to May 2023 had higher contents of thiocyanate than those collected from August to December 2022. The highest average content （7.02 mg/kg） of thiocyanate was observed in the samples collected in May 2023, while the lowest average content （2.95 mg/kg） was observed in the samples collected in September 2022. The change trend of thiocyanate contents in the samples collected from 2 randomly selected dairy farms from January to May 2023 was consistent with that of thiocyanate contents in the 800 samples collected during the same period. There was no significant （P>0.05） difference in thiocyanate content between the samples collected from the 2 dairy farms. [Conclusion] Thiocyanate was commonly observed in raw dairy milk in South Island, New Zealand. It was attributed to the endogenous factor, and the possibility of exogenous addition was extremely minor. There were seasonal variations in thiocyanate content in local raw dairy milk.

Key words: South Island of New Zealand, thiocyanate, raw dairy milk, ion chromatography