Effect of Package Light Transmittance on Vitamin Content of Milk. Part 2: UHT Whole Milk

摘要

This work is the second part of a milk study evaluating the effect of package light transmittance on the vitamin content of milk, in this case on UHT whole milk. The milk was stored at three different light intensities in polyethylene terephthalate (PET) bottles with varying light transmittance as described by Saffert et al. (2006). Changes in the vitamin A, B_2 and D_3 content were monitored over a storage period of 12 weeks at 23℃. Losses in vitamins A and B_2 were most pronounced in completely transparent PET bottles exposed to the highest light intensity. In these bottles, a reduction of the light intensity reduced the vitamin A loss from 88 to 66%, while in the case of vitamin B_2 the complete decomposition was just delayed from 4 to 8 weeks storage. The vitamin D_3 losses in clear PET bottles were almost independent of the light intensity. For pigmented PET bottles, the impact of package light transmittance and light intensity differed for each vitamin. An increase in package light transmittance and light intensity was found to be most decisive for vitamin B_2 stability. In the case of vitamin D_3, only the increase in light intensity was found to be of relevance, whereas for vitamin A stability the influence of increased package light transmittance and light intensity could not be clearly observed. In dark-stored 'control' samples, the analysed vitamins were almost stable.