Effectiveness of PoIy(ethylene terephthalate) and High-Density Polyethylene in Protection of Milk Flavor

摘要

The development of certain off flavors in whole milk (3.25/100 milk fat) as related to packaging material glass, high-density polyethylene (HDPE), amber poly(ethyl- ene terephthalate) (PETE), clear PETE, and clear PETE-UV] were evaluated after exposure to fluorescent light (1100 to 1300 lx) for 18 d at 4"C. Control samples packaged and stored under identical conditions were wrapped in foil to prevent light exposure. Selected fla- vor compounds in milk were measured analytically on d 0, 7, 14, and 18 of storage, while intensities of "oxida- tion,,, "acetaldehyde," and "lacks freshness" off flavors were determined by sensory analysis at the same inter- vals. In light-exposed samples, oxidation off flavor was significantly lower when packaged in amber PETE ver- sus other containers. Milk packaged in HDPE contain- ers showed a significantly higher level of oxidation off flavor than milk packaged in PETE-UV containers but not higher than clear PETE or glass containers. No significant difference in acetaldehyde off flavor was found between package material treatments (exposed or protected). Acetaldehyde concentration never ex- ceeded flavor threshold levels, regardless of packaging material. Amber and PETE-UV materials proved to be a competitive packaging choice for milk in preserving fresh milk flavor.