COMPUTATION OF MECHANICAL STRESSES IN BELGIAN ENDIVE DURING POSTHARVEST STORAGE BY MEANS OF FINITE ELEMENT STRUCTURAL ANALYSIS
Red discoloration is an important quality disorder of Belgian endive (Cichorium intybus L.) and results from cell damage and subsequent oxidation of phenolic compounds during postharvest storage. The mechanism is unknown so far, but a correlation between the length of the floral stem (core) and the occurrence of the disorder has been observed. In this contribution it is hypothised that the floral stem, which continues to grow during postharvest storage, induces mechanical stresses in the intermediary leaves which ultimately result in cell rupture. As a consequence, phenolic substrates and polyphenol oxidases, which are compartmentalised in intact cells, may merge and lead to red coloured polyphenolic compounds. For validating this hypothesis, the development of mechanical stresses in the intermediary leaves of chicons during postharvest storage has been analysed using the finite element method. The shape changes of the leaves were determined through NMR images of the chicory head, obtained over a five day shelf life period. Stress distributions were computed from these shape changes. The calculated stress pattern showed a remarkable agreement both in position and shape with the actual visual observation of the red discoloration.
Verlinden, B.E., Vanstreels, E., Gillis, N., Van Hecke, P., De Baerdemaeker, J. and Nicolaï, B.M. (2001). COMPUTATION OF MECHANICAL STRESSES IN BELGIAN ENDIVE DURING POSTHARVEST STORAGE BY MEANS OF FINITE ELEMENT STRUCTURAL ANALYSIS. Acta Hortic. 566, 295-300
chicory, MRI, mechanical damage, stress, structural