One of the main problems in developing edible coatings is their negative effects on gas permeation, and consequent modification of the internal atmosphere of the fruit, which results in accumulation of CO2and stimulation of anaerobic respiration. In the present study, we found that the commercial wax and the CMC/chitosan bilayer coating significantly increased CO2levels in the internal atmospheres of ‘Or’ mandarins and ‘Star Ruby’ grapefruit, but had no significant effects on CO2levels in ‘Mor’ mandarins and ‘Navel’orange (Fig. 3A). In all cases, CO2levels in the internal atmospheres of control and coated fruit never exceeded 3.5% (Fig. 3A).