GAS-EXCHANGE IN CUT APPLES WITH BILAYER COATINGS

Cut apple pieces coated with double layers of buffered polysaccharide/ lipid showed a 50-70% reduction in the rate of CO2 evolution and about 90% decrease in C2H4 as compared with uncoated controls at similar to 23 degrees C. This substantial decline in the rates of gas evolution was attributed primarily to the diffusion barrier properties of the li pid layer and secondarily to the inhibitory effect of the ascorbate bu ffer which contained calcium. Internal CO2 increased and leveled off a t concentrations of similar to 120 mL/L after 8 h. The internal concen tration of C2H4 decreased after an initial rise and reached a low leve l comparable to that observed in the untreated samples after 24 h. The re was similar to 50-75% reduction in the internal O-2 concentration, while the headspace O-2 showed minimal changes. These results suggest that the inhibitory effects of internal CO2 accumulation and O-2 deple tion may be responsible for the reduced gas exchange in the coated fru it.