Abstract:
The mathematical model which comprises of the Fickian diffusion term and the respiration term for calculating the concertration of oxygen and carbon dioxide gases at any time in the modified atmosphere package for ffresh produces was developed. Seven types of respiration mathematical model, namely, linear, polynomial, exponential, Michaelis-Menten: uncompetitive type, Michaelis-Menten: noncompetitive type, Michaelis-Menten: competitive type, and Langmuir were employed. The computer program was written to solve the mathematical model with the 4th order Runge Kutta method. The calculated reselts were compared with 6 experimental works available in the journals. Additionally, the effects of package surface area (A), the polymer film thickness (L), the permeability of O, and CO, through film (Po, Pc), the weight of fresh produces (W), the free volume in package (V), and the initial gas concentrations in package on the equilibrium concentration of O2 and CO2 (%O2(cq), %CO2(cq)) and the time to reach equilibrium (tcq) were studied. The developed mathematical model found to predict the concentration of O2 and CO2 at any time in good agreement with the experimental results. Overall, the mathematical model with respiration term of the Michaelis-Menten: uncompetitive type or Michsrlid-Menten: noncompetitive type were found to fit the data better than the model with other types of respiration model. Additionally, for the case studied it was found that when A was increased, the %O2(cq) was increased but %CO2(cq) and tcq were decreased. When L, W were increased, the %O2(cq) was decreased but %CO2(cq0 was increased. However, when L was increased, tcq was increased; but when W was increased, tcq was decreased. When Po was increased, %O2(cq) and tcq were decreased. When Pc was increased, %CO2(cq) and tcq were decreased. The V had not effect on %O2(cq) and %CO2(cq); but when V was increased, the tcq was increase. The initial gas concemtration had no diffect on %O2(cq) and %CO2(cq); but the closen the initial gas concentrations were to %O2(cq) and %CO2(cq) the smaller the tcq.