Stability of vitamins A and C in fortified yogurt.

Plain and raspberry flavored low fat yogurt samples were fortified with various commercial forms of vitamins A and C under actual production conditions. Immediately after processing, yogurt samples were kept at 3 degrees C for 6 wk and were analyzed biweekly for pH, titratable acidity, and vitamins A and C. Data revealed that both vitamins decreased gradually in fortified yogurt with vitamin C decreasing at a higher rate than vitamin A. However, a fortification level of 10,000 IU of vitamin A and 300 mg of vitamin C per 227 g container of plain or flavored yogurt provided at least 100% of the US recommended daily allowance of both vitamins after 6 wk storage at 3 degrees C. This level of fortification did not significantly change pH, titratable acidity, or sensory characteristics of yogurt samples.