Stability of Vitamin D3 in fortified yoghurt and yoghurt drink (Doogh).

BACKGROUND: Vitamin D deficiency and insufficiency are recognized as a worldwide problem with serious consequences. Fortification of foods with Vitamin D is a certain approach to improve serum Vitamin D status if the stability of vitamin in the foodstuffs was controlled. The purpose of this study was to examine the stability of Vitamin D3 added to low-fat yogurt and yogurt drink "Doogh" during the products shelf-life.

MATERIALS AND METHODS: Two kinds of Vitamin D3, water- and oil-dispersible forms, suitable for food fortification, were compared to find out whether they show different stability in the products. The products were packed in opaque or translucent containers. The content of Vitamin D3 was determined by high performance liquid chromatography method.

RESULTS: Vitamin D was not affected by the heat treatment (pasteurization) and other processes (homogenization and fermentation). Both water- and oil-dispersible forms were stable during the shelf-life of yogurt samples packed in opaque containers. The Vitamin D3 content of yogurt fortified with water-dispersible form and packed in translucent containers was not stable during the shelf-life and significantly reduced after 1, 2, and 3 weeks of storage compared to the day 0. The Vitamin D3 content of samples fortified with the oil-dispersible form packed in the same container was only stable after 1-week and significantly reduced after 2 and 3 weeks of storage. The Vitamin D3 content of Doogh packed in the opaque containers remained stable during the shelf-life while it was not stable in the samples packed in translucent containers.

CONCLUSION: The results suggested that both forms of Vitamin D are suitable for fortification, and opaque container is a better choice for packaging of the product.