Characterisation of Reddening in Etiolated Chicory Leaves (Cichorium intybus L. var. foliosum)

Chicory (Cichorium intybus var. foliosum Hegi) is a vegetable for which high quality standards determine its value throughout the production chain. Different morphological and physiological defects will lead to an inferior product, lowering the product value, reducing shelf life and making the product less attractive to consume. One kind of physiological defects occurring both at harvest and during storage is red discoloration in the chicory heads (reddening). Little is known about this abnormality in chicory, which is assumed to result from cell damage and subsequent oxidation of phenolic compounds. In this study effects of different environmental parameters (e. g. forcing temperature, storage temperature) and root properties (e. g. harvesting time, type of hybrid) with a potential influence on the degree of reddening after forcing, were evaluated. Important physiological characteristics such as free amino acids, were measured in both the roots and produced chicons. A comparison was made between reddening at harvest and reddening development during storage of the chicory heads. For the three hybrids ('Mont Blanc', 'Metafora' and 'Vintor') investigated in this study, it can be stated that sensitivity for reddening is hybrid specific. Moreover, the amount of remobilized free amino acids from the roots has been found indicative for red discoloration. Finally, temperature control trough the whole endive chain is of crucial importance, because higher temperatures (+4 degrees C) exacerbate reddening.