BIOCHEMICAL-CHANGES IN SOME TROPICAL FRUITS DURING RIPENING

Changes during ripening in alcohol-insoluble solids (AIS) and dietary fibres of mango, guava, date, and strawberry as tropical fruit are described. The activities of various degradative enzymes in the fruits were also investigated. The results showed that the AIS and texture declined rapidly during ripening. The dietary fibres decreased as the fruits lost their firmness and became soft. Polygalacturonase and cellulase activities of the fruit tissues increased markedly during ripening in mango, guava, and strawberry fruits. Both polygalacturonase and cellulase were absent or present at only a low level in the green date but displayed large increases in activity during ripening. The changes in polygalacturonase and cellulase activity were reflected in a reduction in fruit firmness and a decrease in anhydrogalacturonic acid (AGA) and cellulose content during ripening. Pectinesterase (PE) activity decrease in mango, guava, and strawberry fruits during ripening, but its activity was increased in date during ripening, although the degree of esterification (DE) of pectin decreased.