SPATIAL MODELLING OF GAS EXCHANGE IN CUCUMBERS

Modified Atmosphere Packaging (MAP) has been used for a long time to preserve quality of fresh or minimal processed products.
Applying MAP to freshly harvested cucumbers introduces an additional factor into the gas composition: the relative humidity (RH). Since cell turgor controls the structure of the fruit, any loss of water induces a stress which, in turn, increases the speed of the maturation process and reduces the storability of the commodity.
High RH in the in-between space is therefore desired, but simultaneously any condensation should be avoided.
To study these effects, a flow-through system has been designed to monitor the air composition under quasi steady-state conditions.
The high frequency of results from these experiments was used to develop new ways of modelling water losses from the cucumber fruit.
The exponential decay observed for the water loss from the commodity has been confronted with various models of the interaction between air humidity and surface resistance of the cucumber over time.
Simulation using the Finite Element Method (FEM) allows complex geometry to be taken into account.
Fluxes through small surface apertures like stomata or film-perforations can be numerically simulated without introducing instability in the spatial modelling.
It is therefore possible to study the mechanisms modifying the permeance of the skin, as well as the shape of the stomata.

IV International Conference on Postharvest Science

J.B. Cazier, T. Nilsson, V. Gekas

Modified Atmosphere Packaging, Finite Element Method, stomata, transpiration

https://doi.org/10.17660/ActaHortic.2001.553.139