Some factors affecting oxygen transmission rates of plastic films for vacuum packaging of meat

Abstract

SummaryFilm composition, temperature and humidity affect the oxygen transmission rates of some films used for the vacuum packaging of meat.Of the transparent films suitable for meat included in the investigation, those which include polyvinyl alcohol or polyvinylidene chloride offer the greatest barriers to oxygen. Oxygen transmission rates (OTR) at 3.5°C (i.e. near the recommended storage temperature for vacuum packed chilled meat) are only 5–15% of those at 25°C.High humidity increases the OTR of nylon based films, but the effect is less marked at 3.5°C than at 25°C. At 25°C the OTR reduces to rates expected at 75% r.h. within 50 hr of a change in relative humidity from 98 to 75%. Humidity has a negligible effect on the OTR of films containing PVDC.Shrinking of heat shrinkable films reduces the oxygen transmission rate approximately in proportion to the reduction in surface area.The practical implications of the findings are discussed. Relative humidities near 100% r.h. for OTR measurements probably closely simulate the r.h. conditions within cartons of vacuum packaged meat. OTR measured at 20–25°C do not indicate the performance of a film at 0°C, although they do provide a guide to the performance of a given film relative to alternative films of similar composition.