Interaction of temperature control deficiencies and atmosphere conditions during blueberry storage on quality outcomes

• Delays in cooling of blueberries resulted in impacting weight loss increases only.
• Low O2, high CO2 atmospheres resulted in the least decay.
• Low O2, high CO2 atmospheres also tended to cause reduced firming.
• Cultivar specific optimising of O2 atmosphere to combine with high CO2 is required.
• Minimising temperature variability during transport will improve delivered quality.

Southern hemisphere blueberry producers often export their products through extended supply chains to Northern hemisphere consumers. During extended storage, small variations in temperature or atmosphere concentrations may generate significant differences in final product quality. In addition, relatively short delays in establishing cool storage temperatures may contribute to quality loss. In these experiments a full factorial analysis was done of the effects of three cooling delays (0, 12 or 24 h at 10 °C), three atmosphere concentrations (air, 10% CO2 + 2.5% O2 and 10% CO2 + 20% O2) and two storage temperatures (0 °C and 4 °C) which were assessed for their impact on final quality, measured as weight loss, firmness and rot incidence. Two blueberry cultivars were studied: ‘Brigitta’, a highbush cultivar, and ‘Maru’, a rabbiteye. Delays in cooling had a small effect on final product weight, whereas variation in storage temperature and atmosphere during simulated transport influenced both firmness and rot incidence. Atmospheres with 10% CO2 reduced decay incidence, particularly at low oxygen concentration (2.5% O2), although the latter conditions tended to soften fruit. In order to achieve optimal postharvest storage for blueberries, minimising temperature variability in the supply chain is important, as is finding the potentially cultivar-specific optimal combination of high CO2 and low O2 concentration that results in simultaneously minimising rot incidence and induced softening.