Extension of the postharvest life of `Pollock' avocado using modified atmosphere packaging

Introduction. The postharvest life of `Pollock' avocado, a popular cultivar grown in Sri Lanka, is 7-10 d at room temperature. A short postharvest life limits its export volume by sea freight. Materials and methods. Pollock avocado fruit were packaged in 0.05 mm thick low-density polyethylene (LDPE) bags to create a modified atmosphere (MA), and they were stored at 12 °C and 94% relative humidity. The effect of the potassium permanganate, an ethylene absorber, and of the granular charcoal, a carbon dioxide absorber, on modifying the in-package atmosphere was tested. During storage, carbon dioxide, oxygen and ethylene contents were measured. The packages were opened after MA storage, and the fruit ripened naturally under ambient conditions. The weight loss, changes in firmness, total soluble solids (TSS), pulp color, visual quality rating (VQR), chilling injury index (CI) and disease index (DI) during or after storage were determined. Results. Compared with the samples packaged without absorbers, those packaged with absorbers had significantly lower carbon dioxide and ethylene contents. MA packaging was effective in extending the postharvest life of Pollock avocado up to 17 d. Inclusion of absorbers further extended the postharvest life up to 29 d. Firmness, TSS, pulp color, VQR, CI and DI of the ripened fruits were not significantly affected by the MA conditions. Discussion. The MA conditions did not alter the ripening process and were successful in preventing the chilling injury and diseases. Packaging of Pollock avocado in 0.05 mm LDPE bags at 1:1 surface to weight ratio (cm$^2\cdot$g-1) with ethylene and carbon dioxide absorbers and storing at 12 °C and 94% relative humidity can be recommended to extend their storage life up to 29 d