Prolonged storage of 'Hass' avocado fruit using modified atmosphere packaging

An attempt was made to characterize prolonged modified atmosphere (MA) storage of 'Hass' avocados (Persen americana Mill.) for commercial application in terms of optimal thickness of polyethylene (PE) bags, optimal storage temperature, appropriate ratio between the amount of fruit and the size (surface area) of the bags, and maximal storage period without chilling injury (CI). The best result was obtained with 30 mu m PE bags (40 x 70 cm) containing 3.2 kg fruit and stored at 5 degrees C. The oxygen level in these bags was reduced to approximately 4%, the accumulated carbon dioxide reached values of around 5% at storage temperatures of either 5 or 7 degrees C, while the lowest ethylene concentration was detected at 5 degrees C. Development of CI during storage, manifested as pulp discolouration, was not significantly affected by the different thickness of PE bags tested (30-50 mu m). Fruit stored at 5 degrees C remained firmer than those stored at 7 degrees C, and the fruit keeping quality in completely sealed bags providing MA was superior to that in perforated bags or unwrapped controls, Storage in sealed PE bags also reduced weight loss and slowed down the development of black pigmentation in the peel: nevertheless, the fruit peel reached its characteristic dark colour at full softening, This work demonstrates for the first time the potential for long-term storage (up to 9 weeks) of 'Hass' avocado fruit under MA in a commercial size package. (C) 1997 Elsevier Science B.V.