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

Abstract

The development of certain off-flavors in whole milk (3.25% milk fat) as related to packaging material [glass, high-density polyethylene (HDPE), amber poly(ethylene terephthalate) (PETE), clear PETE, and clear PETE-UV] were evaluated after exposure to fluorescent light (1100 to 1300 lx) for 18 d at 4 degrees C. Control samples packaged and stored under identical conditions were wrapped in foil to prevent light exposure. Selected flavor compounds in milk were measured analytically on d 0, 7, 14, and 18 of storage, while intensities of "oxidation," "acetaldehyde," and "lacks freshness" off-flavors were determined by sensory analysis at the same intervals. In light-exposed samples, oxidation off-flavor was significantly lower when packaged in amber PETE versus other containers. Milk packaged in HDPE containers 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 exceeded 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.

Effect of light transmittance and oxygen permeability of various packaging materials on keeping quality of low fat pasteurized milk: chemical and sensorial aspects

“…Current sensory results are in agreement with those of Van Aardt et al (2001) who reported better milk keeping quality in amber PET and UV compounded PET vs. clear PET bottles as well as those of Cladman et al (1998) who reported superior milk protection against light oxidation when packaged in green PET vs. clear PET bottles. What should be stressed at this point is that even though the total microbial count was in all cases below the ''so called'' upper limit for acceptability 10 6 -10 7 cfu mL À1 the organoleptic characters of the product had clearly deteriorated resulting in an unacceptance product.…”

“…Spectral transmission characteristics over the wavelength range of 350-780 nm (Rysstad et al, 1998;Van Aardt et al, 2001) for all packaging materials were measured with a Shimadzu, model 2100 UV-VIS recording spectrophotometer.…”

“…oder et al, 1985;Rysstad et al, 1998). More recently, polyethylene terephthalate (PET) and coextruded HDPE bottles have been used for fresh milk packaging (Bakish & Hatfield, 1997;Cladman, Scheffer, Goodrich, & Griffiths, 1998;Van Aardt et al, 2001). PET has excellent mechanical properties, a good barrier to oxygen and reduces the adverse effects of light on milk quality in the form of pigmented bottles.…”

Effect of ultrasonication on microbiological, chemical and sensory properties of raw, thermized and pasteurized milk

“…A panel of 17 individuals consisting of faculty and graduate students of the Department of Chemistry were trained, in two sessions, for a period of three weeks to differentiate between various off-flavours in milk samples by preparing and evaluating common off-flavour reference standards (light oxidized, plastic acetaldehyde and lack of freshness) (Van Aardt, Duncan, Marcy, Long, & Hackney, 2001). Sensory data were collected between days 0 and 8 of storage.…”

UV-Blocking Film for Food Storage using Titanium Dioxide

“…It is also possible that the migration of certain organic UV absorbers contained in UV-blocking films affects food safety (Pascall et al, 1995). For these reasons, the development of a safe and transparent UV-blocking film is currently required in the food industry (Fanelli et al, 1985;Irissin-Mangata et al, 2000;Schroder et al, 1985;Van Aardt et al, 2001).…”