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

Abstract

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 0.225mm) 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 25–31days for the EMAP at 12 and 17°C, and 35–38days for the EMAP at 6°C. Based on the changes of the measured properties, the most favorable EMAP configuration was 6°C and 8.2kPa of O2–5.8kPa 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*.