Overview
The authors made yoghurt, buttermilk (diluted, salted yoghurt) and butter in the laboratory from the milk of Awassi sheep at a university farm, and measured sodium, magnesium, potassium, manganese, copper, zinc, arsenic, selenium, cadmium and lead by ICP-MS. Arsenic, cadmium and lead were below the limit of detection in all four matrices. Copper and manganese rose sharply in buttermilk, which the authors attribute to added water, salt or metal containers.
Key numbers
- Arsenic, cadmium and lead below LOD in milk, yoghurt, buttermilk and butter (Table 2, p. 97).
- Copper 73.5 ppb in milk, 71.5 in yoghurt, 1230 in buttermilk and 24.6 in butter (Table 2, p. 97).
- Zinc 2683.5 ppb in milk and 3692 ppb in yoghurt; selenium 282.5 to 447 ppb (Table 2, p. 97).
Methods (brief)
One gram of sample digested with nitric acid and hydrogen peroxide by microwave; ICP-MS (Agilent 7500ce). The LOD value and number of samples are not stated, and no reference material or recovery is reported.
Evidence Fitness
Dairy proxy for fromage-frais: no fresh cheese was measured, so that page is not linked. A single farm and one batch of each product, with an unstated LOD, so the non-detects cannot be bounded. The text gives buttermilk manganese as 11.5 ppb while the table shows 111.5 ppb.