Vitamin D3 in High-Quality Cow Milk: An Italian Case Study

Abstract

The quality-labeling category of high-quality (HQ) milk defined by the Italian legislation must comply with specific requirements concerning rigorous breeder management, hygienic controls, fat and protein content, bacterial load, somatic cells, lactic acid content, and non-denatured soluble serum proteins. However, there is no specification for the vitamin D content of HQ milk. Moreover, the data on the vitamin D content of this milk category are very scarce. In the present study, the content of vitamin D3 was evaluated in HQ raw and pasteurized cow milk obtained from Italian cowsheds and supermarkets. The vitamin D3 content varied from not detected (less than 1 µg L^-1) to 17.0 ± 2.0 µg L^-1 milk and was not related to the milk fat content. These results represent a case study including a significant although not exhaustive part of the contemporary Italian market of HQ milk. It was shown for the first time that HQ raw milk does not necessarily contain more vitamin D3, even though non-expert consumers likely to buy milk labeled as HQ could expect it. The vitamin D3 content in HQ pasteurized whole milk should be reported on the label of the milk package as a best practice of consumer information policy.

Keywords: Italy; cholecalciferol; consumers; high-performance liquid chromatography (HPLC); high-quality cow milk; mass spectrometry; pasteurized cow milk; raw cow milk; vitamin D3.

Figure 1

HPLC/UV-DAD traces of a high-quality (HQ) milk sample showing the natural presence of vitamin D3 (a) and absence of vitamin D2 (top panel); the same HQ milk sample spiked with vitamin D2 (b) (central panel) and spiked with both vitamin D2 (b) and vitamin D3 (a) (bottom panel). Peak identification: a, vitamin D3 (naturally present or spiked); b, vitamin D2 (present only in the spiked samples).

Figure 2

Mass fragmentation of the pseudomolecular ion (M + 1 = 385)⁺ of vitamin D3.