Cell-wall modifying enzyme activities in peel and juice tissues of Kinnow fruits at various stages of maturity

Activity of polygalacturonase, cellulase, β-D-galactosidase and pectin methyl esterase in peel and juice tissues changed significantly during fruit maturation. The polygalacturonase activity in peel tissue increased whereas in juice tissue fluctuated with the advancement of maturity. In peel tissue, β-D-galactosidase enzyme showed higher activity up to 50% colour-turning of fruit surface and then decreased slightly at mature stage, whereas in juice tissue, its activity fluctuated during fruit maturation. The cellulase activity in peel and juice tissues followed the increasing trend. However, its activity was higher in juice tissue than those in peel tissue. The PME activity in peel tissue decreased while in juice tissue increased significantly during fruit maturation. The decrease in PME activity after colour-break stage was faster, indicating that the role of PME activity was over after making the pectin substances for PGA to act upon.