Compositional and enzymatic changes in guava (Psidium guajava L.) fruits during ripening

Changes in chemical composition and hydrolytic enzyme activities in guava f ruits cv. Lucknow-49 have been reported at four different stages of maturit y, viz., mature green (MG), color turning (CT), ripe (R) and over ripe (OR) . Chlorophyll content decreased, while carotenoid content increased with ad vancement of ripening. Starch content decreased with concomitant increase i n alcohol soluble sugars. The cell wall constituents viz., cellulose, hemic ellulose, and lignin decreased up to R stage, while the pectin content decr eased throughout up to OR stage. Among the cell wall hydrolyzing enzymes, p olygalacturonase (PG) and cellulase exhibited progressive increase in activ ity throughout ripening, while pectin methyl esterase (PME) activity increa sed up to CT stage and then decreased up to OR stage. The maximum increase in the activities of cell wall hydrolysing enzymes was observed between MG and CT stages. The activities of starch hydrolyzing enzymes, alpha -amylase and beta -amylase decreased significantly with advancement of ripening. Th ese changes in the activities of hydrolyzing enzymes could be considered go od indicators of ripening in guava.