Evaluation of plastic packages for Guava refrigerated preservation

Guavas cv. 'Kumagai' were packed in several plastic materials and stored at 10 degreesC and 85-90% relative humidity (RH)for 7, 14, 21 and 28 days (+3 days at 25 degreesC). The plastic materials studied were: multilayer co-extruded polyolephine film with selective permeability (PSP), low-density polyethylene film (LDPE), LDPE film with mineral incorporation (LDPEm) and heat-shrinkable polyolephine film (SHR). Guavas not packed were taken as control samples. The physicochemical characteristics of the fruits, O-2 and CO2 transmission rates of the packaging materials and gas composition at the package headspace were evaluated The LDPE film, 69 mum in thickness, with the lowest permeability to both O-2 and CO2, Zed to anaerobiosis and high CO2 concentration inside the packages and promoted physiological disturbances and changes in fruit flavour. The SHR film 15 mum in thickness, was the most permeable to CO2 and had quite high O-2 transmission, which modified the inner atmosphere of the packages slightly. The fruits packed in this film showed a poorer quality than the controls, possibly due to the heat produced during the shrinking of the film. The LDPEm film 24 mum in thickness, was almost as permeable to CO2 but had reduced O-2 transmission, promoting an atmosphere of equilibrium of 3% O-2 and 4.5% CO2. Fruits packed in this film kept their skin colour and pulp firmness, suitable for consumption up to 14 days. The PSP film, 35 mum in thickness, had the greatest O-2 transmission but just over half of the CO2 transmission of LDPEm, promoting an atmosphere of equilibrium of 0.5% O-2 and 4.5% CO2 inside the packages. Fruits packed in such packages kept their physicochemical characteristics up to 21 days. Copyright (C) 2001 John Wiley & Sons, Ltd.