ISHS Acta Horticulturae 464: International Postharvest Science Conference Postharvest 96
TEXTURE CHANGES ON NORMAL AND LONG SHELF-LIFE TOMATO (LYCOPERSICON ESCULENTUM MILL.) FRUIT RIPENING |
| Authors: | L. Chiesa, L. Diaz, O. Cascone, K. Pañak, S. Camperi, D. Frezza, A. Fraguas |
| Abstract:
Extending the shelf-life of tomato is very important for both domestic and export marketing. Susceptibility of tomato fruit to physical damage during handling, storage and transport is related to texture. Texture is an important attribute to evaluate quality of tomato fruits, and it is determined by fruit morphological and physiological characteristics: epicarp firmness, amount of locule tissue and maturity stage. Postharvest decreases in fruit firmness are an important component of the palatability that accompanies fruit ripening. In part, the loss of firmness experienced by tomato fruit upon ripening is attributable to dissolution of the arrangement of cell-wall and middle lamella polysaccharides. Pectolytic enzymes are involved in pectin degradation and softening of the tomato fruit during ripening. This study was designed to relate changes in tomato fruit texture with physical, chemical and biochemical parameters. Greenhouse-grown tomato fruits of cv. ‘Iván’ (B.N.H. - U.S.A), normal hybrid, and ‘Graziela’ (Gedera - Israel), long shelf-life hybrid, were obtained from a commercial source. Fruits were stored at 10°C and 20°C during 5 weeks. Measurements of weight loss, firmness (quantified with a penetrometer), pectolytic activity and cation content (Ca2+, Mg2+, K+ measured by capillary electrophoresis) were made during 5 weeks. A completely randomized block design was used, and data obtained were evaluated by simple correlations between pairs of parameters. Firmness of tomatoes was inversely related to weight loss. The incidence of decay was related to the storage temperature and the cultivar. Higher firmness values were obtained with a long shelf-life hybrid and storage at 10°C. No relationship between pectinesterase activity and storage temperature, maturity stage at harvest and type of hybrid was observed. Polygalacturonase (PG) activity increased with the storage period and temperature. High correlations were found between PG activity and firmness, and Ca2+ content with firmness. No relationships between firmness and content of other cations were obtained. | |
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