Comparing the Function of Perforated and Non-Perforated Film in Modified-Atmosphere Packaging: Impact on the Quality of Broccoli

A wide range of steady-state O-2 partial pressures (0.1 to 18 kPa) was obtained in perforated and non-perforated packages composed of low density polyethylene (LDPE) film at 0 and 10 degrees C for the storage of broccoli (Brassica oleracea L. var. italica). Half of the broccoli was treated for 24 h at 10 degrees C with 1 ppm 1-MCP prior to storage. The combinations of steady-state O-2 and CO2 partial pressures achievable depended on whether the film was perforated or not. The regression fitting the O-2 versus CO2 headspace data for non-perforated packages was linear with a negative slope such that for every 4 kPa decrease in O-2, there was a 1 kPa increase in CO2. The curve fitting the data for perforated packages was also linear and negative, but steeper, such that for every 4 kPa decrease in O-2, there was a 4 kPa increase in CO2. The result was that for a given steady-state O-2 concentration, the CO2 concentration was higher in the perforated package compared to the non-perforated packages. For florets stored at 10 degrees C, the higher CO2 in the perforated packages resulted in higher visual quality and better color retention was significantly better than in the non-perforated packages for packages with O-2 levels greater than approximately 2 kPa. There was no effect of the elevated CO2 for the florets stored at 0 degrees C. 1-MCP application only had a small positive impact on floret quality at 10 degrees C and no effect at 0 degrees C. The data suggest that combination of both perforated packages and 1-MCP application on broccoli florets may have the potential to provide some protection against rapid quality loss when the storage temperature exceeds the recommended 0 degrees C.