Evolution of Qualitative Characteristics during Blueberry Fruit Storage in a Modified Atmosphere

The objective of this work was to evaluate the performance of different films to maintain MAP conditions for storing ‘Duke’ blueberries by verifying the evolution of qualitative traits of berries. The fruits were picked manually, individually deposited in polyethylene baskets and immediately transferred (1 h) to the laboratory under chilled conditions (10°C). The experimental storage units consisted of a pallet bag of two different types of film, polyethylene (100 μm) and a biobased film derived from starch (50 μm). The O2 and CO2 transmission rates, measured according to the ASTM F 2622-08 and ASTM F 2476-05 methods at 38°C and 90% RH, were, 2642 and 10654 [cm3/(m2·24 h)], respectively, for the polyethylene film and 655 and 1384 [cm3/(m2·24 h)], respectively, for the biobased film. The initial gas composition of the active MAP (11.2 kPa of O2, 10.3 kPaCO2 + 77.8 kPa N2) was chosen based on a previous report with some modifications. The flow-through system used to modify the atmosphere operates with high and lowpressure sides using CO2, O2 and N2. The air present in the pallet bags was partially substituted with the desired gas mixture. A manual timer regulated both the time of evacuation and filling with CO2. There was one pallet bag (with a volume of 1,728,000 cm3) for each treatment containing about 150 kg of blueberry fruits. The pallet bags were stored for up to 45 days at 1±1°C and at 85-90% RH. The results of both treatments were compared to a control (fruits stored in normal atmosphere). The overall results indicate that blueberry storage can be effectively extended by exposing the fruit to a cold environment and an adequate atmosphere composition. The 11.2 kPa of O2, the 10.3 kPa CO2 atmosphere composition reduced the changes in soluble solids content and acidity, and maintained acceptable levels of anthocyanins and phenolics.