Modified atmosphere storage and bitter pit reduction in ‘Cox's Orange Pippin’ apples

Abstract

Incidence of the physiological disorder bitter pit was reduced by storage of cultivar ‘Cox's Orange Pippin’ apples at 1°C in 25-μm thickness polyethylene bags (polybags) in which there were a number of 1-mm microperforations. Concentrations of CO 2 increased and O 2 decreased as the number of microperforations per bag was reduced. These changes were associated with reduced levels of bitter pit. It is suggested that 50–70 microperforations per polybag, of sufficient size to fit inside an 18.5-kg carton, could be used commercially to reduce bitter pit and maintain quality of fruit stored for 6 weeks at 1°C, and then kept at ambient temperatures within the polybags for an additional 7 days. The effectiveness of microperforated polybags and vacuum infiltration with CaCl 2 in reducing bitter pit was compared over 3 seasons. The results were variable, with polybags being more effective than vacuum treatment in 2 of the 3 seasons, and vacuum treatment better than polybags in 1 season. Neither method reduced bitter pit to commercially acceptable levels when the non-treated fruit had levels of bitter pit exceeding 20–30%. When apples were placed in microperforated polybags after vacuum infiltration, up to 20% developed a brown-heart-like disorder.