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 ap plication in terms of optimal thickness of polyethylene (PE) bags, opt imal storage temperature, appropriate ratio between the amount of frui t 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%, th e accumulated carbon dioxide reached values of around 5% at storage te mperatures of either 5 or 7 degrees C, while the lowest ethylene conce ntration 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 t he fruit keeping quality in completely sealed bags providing MA was su perior to that in perforated bags or unwrapped controls, Storage in se aled PE bags also reduced weight loss and slowed down the development of black pigmentation in the peel: nevertheless, the fruit peel reache d its characteristic dark colour at full softening, This work demonstr ates for the first time the potential for long-term storage (up to 9 w eeks) of 'Hass' avocado fruit under MA in a commercial size package. ( C) 1997 Elsevier Science B.V.