Biochemical Studies on Post‐Ripening of Banana

Abstract

Some fundamental studies were undertaken in order to get some insight into the process of post-ripening of banana by studying the changes in carbohydrate metabolism and the changes in respiratory mechanism during the course of banana ripening. 1.During the course of banana ripening, it is concluded that sucrose is synthesized first directly from starch and subsequently hydrolyzed into glucose and fructose in the post-climacteric stage. In this process phosphorylase appears to be the main enzyme involved in the breakdown of starch. 2.During the course of post-ripening, water content of the flesh increases gradually. Soluble pectin increases four times in the climacteric stage, and then decreases. Tannin content remains unchanged. 3.No peroxidase activity is detected through each stage of ripening, but considerable intensity of catalase activity is detected. The catalase activity in pre-climacteric banana is stronger than that in the climacteric. 4.The entire terminal oxidase of preclimacteric banana flesh is cyanide-resistant, but as the climacteric stage reaches, one-fifth of it becomes cyanide-sensitive. Malonate poisoning appeares to occur to a very little extent. 5.Citrate acts as a substrate toward the respiratory system of preclimacteric tissue, but as an inhibitor toward that of ripe banana. An interpretation is made on these effects of citrate. 6.With the aid of the uncoupling agent, 2,4-dinitrophenol, it is shown that the respiratory rate of the preclimacteric but not of the climacteric banana flesh is limited by the capacity of the phosphate transfer system. ATP-ase develops during the course of ripening and appeares to be a factor which put forth the respiratory increase in the climacteric stage. This behavior is belived to be the general feature of the catabolism of reserve substances like starch.