Development of an equilibrium modified atmosphere packaging (EMAP) for feijoa fruits and modeling firmness and color evolution

• EMAP systems were developed for feijoa fruits from previous simulation.
• A suitable EMAP was determined for feijoa fruits from the change in their properties.
• Models are presented to represent feijoa firmness and color evolution in EMAP.
• Firmness and color change was considered as a function of gas levels and temperature.

Equilibrium modified atmosphere packaging (EMAP) improve the preservation of fresh produce by using favorable levels of gases that remain constant for most of the packaging time. In the present study, a set of experiments were conducted to obtain a suitable EMAP system for feijoa fruits (Acca sellowiana Berg cv. Quimba) and to develop suitable mathematical models to describe the evolution in firmness and flesh color of the stored fruits depending on the temperature and O2 and CO2 concentrations inside the package. The fruits were stored without packaging and packed in polypropylene (PP) bags (unperforated and with 1–3 perforations of 0.225 mm) at 6, 12 and 17 °C and 85% RH. The equilibrium concentration of the gases in the packaging headspace for each EMAP was estimated in advance, using a previously developed model. The effect of different storage conditions on the fruits was determined by evaluating the change in the deterioration index, weight, firmness, color and organic acids. In the different EMAP systems, the storage time of the fruits was significantly increased as compared to those stored without packaging at 17 °C, from 17 to 25–31 days for the EMAP at 12 and 17 °C, and 35–38 days for the EMAP at 6 °C. Based on the changes of the measured properties, the most favorable EMAP configuration was 6 °C and 8.2 kPa of O2–5.8 kPa of CO2 (PP bags with one perforation). With the obtained data, the models to represent changes in the fruit firmness and color were successfully developed, obtaining R2adj values of 0.948 for firmness and 0.94-0.95 for the color coordinates L*, a* and b*.