EFFECTS OF MICROPERFORATED POLYETHYLENE BAGS ON THE STORAGE QUALITY OF 'COX'S ORANGE PIPPIN' APPLES

The influence of 25 micron thickness polyethylene bags (polybags) with microperforations, on the storage quality of 'Cox's Orange Pippin' apples has been studied. Bags with 50 microperforations reduced bitter pit incidence and maintained fruit quality, apparently as a result of increased CO₂ concentrations and decreased O₂ concentrations. Subsequent investigations have examined the effects of storage period, storage temperature, and delays at ambient prior to coolstorage. Fruit were stored at 0°C or 3°C for both 42 and 96 days and were then assessed for background colour, flesh firmness, soluble solids and incidence of storage disorders after a further 7 days at ambient temperatures. During short term storage of 42 days, which is a simulated period for New Zealand fruit to reach retail markets in Europe, optimum fruit condition occurred in microperforated bags at 0°C compared with no polybags or commercial polybags. At 3°C, fruit were greenest in microperforated polybags but superficial scald was evident in this treatment. After 96 days, a high incidence of superficial scald was found in all treatments, and was particularly severe in the microperforated polybag treatment at 3°C. At 0°C, a greener background colour was maintained but the low temperature disorder coreflush occurred. An experiment on effect of delay at ambient before storage at 3°C showed that the benefits of microperforated polybags were maintained with delay periods of up to 5 days. However, because of the occurrence of superficial scald in early harvested fruit, the use of microperforated polybags to maintain fruit quality may be restricted to short term storage unless a scald inhibitor such as diphenylamine is used, or fruit from late harvests is used.