Development of an analytical protocol for the estimation of vitamin D(2) in fortified toned milk.

A simple and rapid method has been developed for the isolation and determination of vitamin D2 in fortified milk samples by HPLC. The advantage of the proposed method is that sample preparation time is reduced and both crystalline and encapsulated forms of vitamin D2 can be estimated. The developed protocol involves a few extraction steps and requires less amounts of reagents. The HPLC separation of vitamin D2 was carried out on a reverse phase C18 column with photo diode array detector at 254 nm. Some additional steps were required for extraction of microencapsulated vitamin D2 for breaking down coating material in comparison to crystalline vitamin D2. The recovery of vitamin D2 in fortified toned milk by the proposed method ranged from 96.46% to 99.05%. Non significant degradation was observed in vitamin D2 during seven days storage and also under light exposure (1485 lux) for 32 h.

Bioavailability of vitamin D2 and calcium from fortified milk.

The objective of the present investigation was to determine bioavailability of calcium and vitamin D2 from milk fortified with either calcium or vitamin D2 alone or when both were used for preparation of multiple micronutrient fortified milk and also to study its interaction with iron and zinc bioavailability. 32 weanling male rats (aged 21-28 days) were assigned into four groups and were fed milk and milk fortified with calcium, vitamin D2 and calcium+vitamin D2. Vitamin D2 increased calcium bioavailability. In multiple micronutrient fortified milk, the bioavailability of both calcium+vitamin D2 increased in comparison to single fortification. Calcium fortification decreased, whereas vitamin D2 increased the absorption of iron and zinc. However, calcium and vitamin D2 when fortified in combination, the iron and zinc bioavailability was similar to control group. There was positive association between bioavailability of calcium and vitamin D2.