Effect of Conventional and Alternative Modified Atmosphere Packaging on the Shelf-Life of Fresh-Cut Apples

Processing steps, such as cutting and peeling, increase the respiration rate and ethylene production of apples, quickening senescence phenomena with effects on texture, color and flavor. Packaging in modified atmosphere (MAP) is one of the most used techniques to control this decay. This study concerns both conventional (CO2, O-2, N-2) and alternative (Ar, N2O) gases in active packaging. Apples ('Golden Delicious') were peeled and cut into 8 slices, then dipped for 2 min in 0.5% ascorbic acid + 1% citric acid solution. Half of the slices were not dipped and served as undipped controls. All samples, dipped and undipped, were packed and sealed in polypropylene bowls, previously sanitized by UV radiation. The following atmosphere compositions were used: air (A); 99% N-2, 1% O-2 (B); 90% N-2, 5% CO2, 5% O-2 (C); 65% N2O, 25% Ar, 5% O-2, 5% CO2 (D); 80% Ar, 20% CO2 (E). Analyses were carried out after 1, 4, 8 and 11 days of refrigerated storage at 4 degrees C. Ethylene production, color and firmness were evaluated. Sensory analysis was performed to judge the appearance, firmness and flavor of products. A high ethylene production was observed in samples packed in air, but not in those stored in the other atmospheres. Both conventional mixes (B and C) and the Ar-CO2 combination (E) positively influenced the instrumental firmness values of undipped slices during shelf-life; this beneficial effect was almost completely neutralized by dipping treatment. These same atmospheres (B, C and E) had also a protective effect on color of dipped fruit, which showed a lower browning index. In contrast, these three atmospheres did not limit the browning phenomena in undipped apples, and browning was even enhanced for the Ar-CO2 mix (E). The sensory tests partially confirmed the instrumental results. Concerning firmness, the undipped slices packed in B and E atmospheres, as well as the dipped samples packed in E, obtained the highest scores.