Effect of Package Light Transmittance on the Vitamin Content of Pasteurized Whole Milk

摘要

Pasteurized whole milk (3% fat) was stored under fluorescent light at 8℃ in clear 1 litre polyethylene terephthalate (PET) bottles and three variants of pigmented PET bottles with different light transmittance. Changes in the vitamin content were monitored over a period of 10 days. 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. Data were obtained for vitamin A (retinol), vitamin B_2 (riboflavin) and vitamin B_(12) (cobalamin) content. Standard plate counts were determined to ensure an acceptable microbiological status of the pasteurized milk during the sampling period. In clear PET bottles a reduction of 22% of the initial content was observed for vitamin A and 33% for vitamin B_2, while the vitamin B_(12) content remained almost stable. In all pigmented PET bottles the vitamin retention was significantly higher; the losses were 0-6% for vitamin A and 11-20% for vitamin B_2, depending on the pigmentation level, as compared to 6% for vitamin A and no significant loss for vitamin B_2 in the 'control' sample. An impact of the package light transmittance on the vitamin B_(12) content could not be observed.