Changes in vitamin content of powder enteral formulas as a consequence of storage

The thiamine, vitamin E (α-, γ- and δ-tocopherol) and vitamin A (all-trans and 13-cis-retinol) contents of four commercial powder enteral formulas (A, B, C and D) have been determined. The vitamin intake provided by the studied formulas was always above the US daily recommendations. Powder enteral formulas A and D were stored at 30 °C for up to 6 months with a water activity of 0.44 (Aw = 0.44), and formula A was also stored under atmospheric conditions for 3, 4 and 6 months. Formulas A and D kept at 30 °C and Aw = 0.44 suffered a gradual loss in vitamin content (from 3% to 4% after 1 month to 58–60% after 6 months). Formula A, stored at 30 °C under atmospheric conditions, underwent a slight reduction in vitamin content after 3 months, similar to that found after 1 month with Aw = 0.44, and from that time onward, this decreased steadily (to 30% after 6 months). The RDA of thiamine, vitamin E and vitamin A for women and men were met only when the powder enteral formulas were stored at 30 °C with Aw = 0.44 up to 1 month and without Aw up to 3 months. These results show that Aw and storage period have a marked effect on the stability of thiamine, vitamin E and A during the storage of powder enteral formulas and should be taken into consideration for the shelf-life of the product.