Changes in Pectic Substances and Cell Wall Degrading Enzymes During Tomato Fruit Ripening

Changes in pectic substances and the activity of the cell wall degrading enzymes, such as pectinesterase (PE), polygalacturonase (PG) and cellulase, were investigated during the ripening of ‘Strain-B’ and ‘UC-82’ tomato fruits. Respiration rate progressively increased in a climacteric pattern with peak of respiration at the table-ripe stage. Total and insoluble pectins progressively decreased with fruit ripening, while the soluble pectins increased from the mature-green stage up to the canning-ripe stage. Fruits of ‘UC-82’ had higher total and insoluble pectins and more firm texture at harvest and during all stages of ripening than fruits of ‘Strain-B’. A positive correlation was obtained between total and insoluble pectins and fruit flesh firmness. The protein content and PE activity in both cultivars followed the climacteric pattern of respiration and had increased up to the table-ripe stage and then decreased. PG and cellulase activity progressively increased in a similar manner in both cultivars with a high correlation between increase in enzyme activity and stages of ripening.