Condensation dynamics in plastic film packaging of fruit and vegetables

摘要

Water condensation on the surface of fruit and vegetables causes defects of the external appearance, promotes both the forming of spores and the growth of micro-organisms, and thus accelerates deterioration. Even at low temperature fluctuations of ambient air, condensation on relevant surfaces can be observed due to comparatively high air humidity inside the film packaging. The objective of the present study was to determine condensation dynamics and intensity within plastic film packaging for fruit under changing environmental conditions. Using packages of plums as a test case, it could be shown that water condensation processes occur time-delayed and superimposed with varying intensities on the surface of the fruit, on the inner film surface, and on the inner tray walls. Retention time and intensity of condensation were identified as the substantial components of condensation. In addition to the external temperature cycle the external mass transfer and the air volume within the packaging were taken into consideration. The condensation on the inner film surface was especially influenced by the flow conditions, the external temperature amplitude and the inner air volume. In contrast, condensation processes on fruit surfaces were caused primarily by temperature amplitude and cycle time.