MODEL FOR GAS-EXCHANGE DYNAMICS IN MODIFIED-ATMOSPHERE PACKAGES OF FRUITS AND VEGETABLES

A model for atmosphere in a package containing fresh fruits was analyzed theoretically and validated by experiments with red bell pepper fruit. The model was based on two processes: fruit respiration and film permeability. Mathematical analysis showed that when rates of O-2 consumption and CO2 evolution due to respiration are equal, and film permeability to CO2 is greater than that to O-2, the time course curve of CO2 concentration has a maximum. In a closed system, the time course of the sum of the gases could indicate a change of respiratory quotient. These results are independent of model for respiration. To predict extent of overshoot acid for a computerized simulation, the equation of Michaelis-Menten type with noncompetitive inhibition was adopted to describe respiration. Utilizing computer simulations enabled evaluation of film specifications and package dimensions best for a given commodity.