Effect of package light transmittance on the vitamin content of milk,part 3: Fortified UHT low‐fat milk

This work is the third and last part of a milk study evaluating the effect of package light transmittance on the vitamin content of milk, in this case on fortified UHT low‐fat milk. The milk was stored under light with an intensity of 700 lux in polyethylene terephthalate (PET) bottles with varying light transmittance to monitor the changes in the vitamin A, B₂ and D₃ contents over a storage period of 12 weeks at 23°C. Milk packed in pigmented PET bottles with the lowest light transmittance, which was stored in the dark under the same experimental conditions, served as the ‘control’ sample. In clear PET bottles, a reduction of 93% of the initial content was observed for vitamin A and 66% for vitamin D₃, while the vitamin B₂ content was completely degraded. In all pigmented PET bottles, the vitamin retention was only slightly higher; the losses ranged between 70 and 90% for vitamin A, between 63 and 95% for vitamin B₂, and between 35 and 65% for vitamin D₃ depending on the pigmentation level. In the dark‐stored ‘control’ sample, a 16% loss could be observed for vitamin A, while the level of vitamins B₂ and D₃ remained almost stable. Copyright © 2008 John Wiley & Sons, Ltd.