Stability of vitamin A and E in powdered cow’s milk in relation to different storage methods
¹Czech University of Life Sciences Prague, Faculty of Agrobiology, Food and Natural Resources, Department of Chemistry, Kamýcká 129, 165 21, Prague, Czech Republic 2Dairy Research Institute Ltd, Ke dvoru 791/12A, 160 00, Prague, Czech Republic *Correspondence: michlova@af.czu.cz
Abstract:
In this article, the influence of different ways of storage on the content of vitamin A and E in powdered cow´s milk was studied. The cow´s whole milk powder was taken directly from the manufacturer and stored for one year in 4 different ways – in the light at room temperature, in the dark at room temperature, in a refrigerator at 8°C and in a freezer at -20°C. The content of vitamins was measured 4 times during the first month and then once a month. The samples were stored for one year. Vitamins A and E were determined by HPLC using DAD and FLD detectors. Vitamin A was identified in all samples but only α-tocopherol (out of various forms of vitamin E) was detected in all samples. In all cases steeper decline of both vitamins in first 14 days of storage was identified. The highest losses of vitamin A and E in powdered milk occurred during storage in the light at room temperature. The value decreased by 91 resp. 95% of the original value.
Key words:
milk powder, stability, storage, vitamin A, vitamin E.