CELL WALL CARBOHYDRATE METABOLISM OF PERISHABLE VEGETABLES IN PRE- AND POST-HARVEST

Many horticultural commodities, such as un-topped radish and carrots are produced mainly for the fresh market. These products are highly perishable and subject to high quality losses in postharvest. First symptoms of quality loss are changes in textural properties, i.e. visible wilting symptoms and/or yellowing of the leaves as well as the decrease in firmness and crispness. The cause and the extent of these quality changes are mainly determined by changes in cell wall carbohydrate metabolism and gas exchange. However, cell wall metabolism also depends on environmental conditions during plant growth and on the developmental stage of the product.
In the present investigation the influence of climatic pre- and post-harvest impacts on the dynamics of cell wall carbohydrate metabolism was studied in different tissues of un-topped radish (Raphanus sativus var. sativus L.) and un-topped carrots (Daucus carota L. ssp. sativus (Hoffm.), harvested at two developmental stages. Close correlations were found between internal and external quality characteristics and product responses, i.e. cell wall polysaccharides, textural properties, ethylene evolution (carrot) and chlorophyll fluorescence (radish) which are discussed as an index for the postharvest quality evaluation and quality control.