Re-warming of stone fruits after cold storage.
Linke M., Herppich W.B., Geyer M.
5th International Postharvest Symposium . Volume of Abstract . Verona, Italy 6-11 June 2004. page 18
2004
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Generally, extension of shelf life can be obtained by manipulation of reaction rates due to temperature decrease.However, cooling requires a re-warming step commonly leading to condensation of water at the produce surface at temperatures below the dew point.The amount of condensate is a function of the produce surface temperature and of the surrounding conditions which are strongly affected by the packaging system used.The temperature equilibrium is often obtained not before several hours.If the water remains at the sample surface for a long time period while temperature increases, unwanted microorganisms are able to grow under certain conditions resulting in produce deterioration and reduced shelf life.
The objective of this study was to minimize condensation effects by controlling the air flow conditions close to the produce surface.Cherries and plums in various open packaging were warmed after the cold storage using different flow conditions.The time-dependent amount of condensate was calculated using a certain heat and mass transfer model for the produce in the packaging unit.The data clearly show that low air convection results in small amounts of condensate was calculated using a certain heat and mass transfer model for the produce in the packaging unit.The data clearly show that low air convection results in small amounts of condensate persisting on the product surface in the packaging during extended periods (up to 10 h).Furthermore, reaching the temperature equilibrium demands for a relatively long time.When increasing the air velocity higher amount of water vapour condensates, but remaining on the produce surface for shorter time.Compared tolow convection rates, here the temperature equilibrium is reached much faster.Applying equal air velocities and air flow conditions against and around the packaging resulted in increased water loss of the fruit samples when packed in plastic containers.The presented data point up the effect of air flow condition, packaging and temperature on the postharvest behaviour of stone fruits, resulting in strategies for improved post cold storage handling.