Browning evaluation of ready-to-eat apples as affected by modified atmosphere packaging

The color and polyphenol oxidase (PPO) activity of fresh-cut Golden delicious apples were evaluated throughout cold storage under modified atmospheres. The shelf life of cut apples was extended to several weeks, especially when an initial atmosphere of 90.5% N₂ + 7% CO₂ + 2.5% O₂ and plastic pouches of 30 cm³/cm²·bar·24 h were used. Under these conditions, a maximum 62% PPO activity depletion was observed. In all cases, the faster the initial PPO activity decays, the less the color changes. A fractional conversion first-order model was proposed for predicting color changes in minimally processed apples. Browning was better described through lightness (L*) (k_L = 0.017 - 0.07 day^-1) and color difference (ΔE*) values (k_ΔE = 0.015 - 0.073 day^-1), which fitted the model with enough accuracy.