Increase vitamin D levels in milk.

Vitamin D is essential for maintaining proper bone health. Recognizing the importance of this vitamin in preventing rickets or osteoporosis, milk is fortified with vitamin D. However, the recommended daily intake of vitamin D is expected to increase from 400 to 1,000 international units (IUs).

In response, the level of fortification in milk needs to be increased. Also, consumption of milk in the United States is decreasing. So alternate ways of providing vitamin D need to be explored, such as the fortification of processed cheese and yogurt.

Scientists at South Dakota State University wanted to determine the feasibility of fortifying high temperature-short time (HTST) 2% milk, ultra-high-temperature (UHT) chocolate milk, low-fat strawberry yogurt and processed cheese with 250 IUs of vitamin D per serving. They also wanted to identify techniques that would ensure the uniform incorporation of vitamin D in processed cheese. They also sought to measure the stability and potential flavor defects caused by vitamin D. Their research demonstrates that it's feasible to increase the level of vitamin D fortification in milk and other dairy products.

The scientists fortified samples with vitamin D prior to processing them, using a cold water dispersible vitamin D supplement. The fortification level targeted was 250 IUs of vitamin D per serving. Three replicates of HTST 2% milk, UHT 2% chocolate milk and low-fat strawberry yogurt were produced on a pilot-scale level. A single batch of processed cheese was produced on a commercial scale.

Each product was stored for the duration of its recommended shelf life: 21, 60, 42 and 180 days, respectively. The researchers analyzed the vitamin D content throughout each product's shelf life, as well as flavor differences two-thirds of the way through. It turns out that vitamin D fortification was feasible and stable over each product's shelf life at 250 IUs per serving. No changes in terms of flavor occurred.

Further information. Lloyd E. Metzger, Midwest Dairy Foods Research Center, Dairy Science Department, SHN 023, South Dakota State University, Brookings SD 57007; phone: [phone]; fax: [phone]; email: [e-mail].