ISHS Acta Horticulturae 682: V International Postharvest Symposium
RE-WARMING OF STONE FRUITS AFTER COLD STORAGE |
| Authors: | M. Linke, O. Schlüter, W.B. Herppich, M. Geyer |
| Keywords: | sweet cherry, plum, condensation, atmospheric evaporation, dew point, surface water, boundary layer resistance |
| Abstract:
The shelf life of fruit and vegetables can be extended substantially by decreasing the temperature. Since such horticultural products vary in their temperature-dependent behaviour, different cooling methods are adapted to reach the appropriate product specific temperature level. Cooling requires a re-warming step that commonly leads to condensation of water on the product surface at temperatures below the dew point. The amount of condensate is a function of the product surface temperature and of the surrounding conditions (air temperature, humidity, air flow). Under practical conditions both the warming and the condensation are strongly affected by the packaging system used. The heat and mass transfer between the product in the packaging unit and the environment is a complex process in which temperature equilibrium is often obtained only after several hours. The wet product surface and the increasing temperature offer ideal growing conditions for microorganisms, and affect product quality during storage. The objective of this study was to minimize condensation effects by controlling the air flow conditions close to the product surface. The results show that low air convection results in small amounts of condensate persisting on the product surface in the packaging for up to 10 hours. When the air velocity is increased, more water vapour condenses, but it remains on the product surface for less time. This study illustrates the effect of air humidity and flow conditions on the postharvest behaviour of stone fruits (sweet cherry, plum) that may result in strategies to improve post-cold storage handling. | |
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