Diego A. Castellanos

Respiration and ethylene generation modeling of “Hass” avocado and feijoa fruits and application in modified atmosphere packaging

ABSTRACT A proper description of the respiration and ethylene generation is important in the development of package systems for the preservation of fresh fruits and vegetables. In this work, a model based on both Michaelis-Menten and chemical kinetics equations was developed and assessed in order to describe the respiration and ethylene generation of avocado (Persea americana cv. Hass) and feijoa fruits (Acca sellowiana Berg) from experimental data obtained at different temperatures by a closed system method. The temperature effect in both processes was described using Arrhenius-type relationships. After this, avocadoes and feijoas were packed in perforated low-density polyethylene (LDPE) and polypropylene (PP) bags for 8 days at 12°C and 80% RH to validate the usefulness of the model to describe the gas evolution in modified atmosphere packaging (MAP). For avocado fruits, respiration rates of 2680-3030 cm3 kg-1 d-1 were obtained at 24 °C and normal atmosphere, and 3650-4230 cm3 kg-1 d-1 for feijoa fruits. As for ethylene production rates, at 24 °C were obtained values of 3.11 cm3 kg-1 d-1 for avocado and 0.50 cm3 kg-1 d-1 for feijoa. At 6 °C, respiration and ethylene production rates were up to 6 times lower. It was possible to describe properly the ethylene generation using a Michaelis-Menten simple equation and the respiration rates using a Michaelis-Menten uncompetitive kinetics for both fruits with coefficients of determination above 0.9 in each case. The overall model was validated in the MAP test being possible to predict successfully the O2, CO2 and C2H4 levels inside the packages.

Simulation Of An Active Packaging With Catalytic Oxidation Of Ethylene For 'Cavendish' Banana

In the ripening and senescence of fruits, ethylene plays a major role and therefore, its control is essential to extend the shelf-life of these products. In this study, the kinetics of catalytic oxidation of ethylene was experimentally determined for a catalyst of gold nanoparticles supported on cerium oxides and the use of this was simulated in a perforated rigid packaging system for ‘Cavendish’ bananas. According to the simulations performed, for 1 kg of fruit in the active packaging 5.931 g of the obtained catalyst are needed to reduce 99% of the ethylene concentration at 12°C and with constant concentrations of 0.072 of O 2 and 0.178 of CO 2 (in molar fraction).