Transmission of Light Through Pigmented Polyethylene Milk Bottles

Light transmissions through white and yellow pigmented polyethylene milk bottles were measured in the 350- to 800-nm region. The bottles were opaque below 400 nm. Light transmission at 550 nm was 13 and 17% for the white and yellow pigmented bottles, respectively, compared to 72 and 2% for an unpigmented polyethylene bottle and a paperboard milk carton, respectively. The 400- to 550-nm wavelengths, which apparently are harmful to milk quality, were not entirely blocked by the pigmented bottles. A plastic sleeve for fluorescent tubes in dairy cases was opaque below 385 nm and had 92% transmission in the 440- to 800-nm region.