Modeling of Changes in Atmosphere Composition in Fresh-cut Peach Packages due to Temperature Fluctuations

Storage temperature is not always constant in the distribution chain of modified atmosphere fresh food packages. A change in temperature means an alteration in the respiration rate of the product and in the gas transmission rates through the film. Because of their high metabolic activity, minimally processed products are particularly sensitive to temperature variation, and hence this study has been carried out with five cultivars of fresh-cut peaches (Prunus persica). Their respiratory activity has been determined by a closed system at 4, 15, and 25 °C. The peach segments are wrapped in microperforated films whose transmission rate is determined according to the size of the microperforations (between 100 x 130 μm and 215 x 190 μm). To quantify the effect of temperature fluctuations (5 h at 25 °C) on the O₂ and CO₂ concentrations of the packaging atmosphere of the product, a mathematical model has been applied. Using experimental data, it has been established that the rate of O₂ consumption is a potential function of the O₂ concentration, while the production of CO₂ is linear. Although, all cultivars are of nonmelting fresh with no big differences in respiratory activity; these differences are accentuated with O₂ concentrations greater than 10% and raising the temperature. The solution of the model provides knowledge of the behavior of the product during its nonstationary period and equilibrium once reached. The results show in all cases that the CO ₂ concentration is more sensitive (increase of 5 units) to a break in the cold chain than that of O₂ (reduction of 2 units).