Biochemical studies related to textural regulation during ripening of banana and mango fruit

The changes occurring during ripening of "Cavendish" banana and "Alphonso" mango were studied, with emphasis on carbohydrates and the carbohydrate hydrolases responsible for textural softening. In both banana and mango there was a significant increase in soluble sugars, mainly in the reducing types. There was a gross increase in uronides and a steady decrease in starch, cellulose, hemicellose and pectins during each stage of ripening. The new observation made in the present study is that xylanase and laminarinase among the glycanases, and alpha-mannosidase followed by beta-galactosidase among glycosidases, appeared to play a crucial role in textural softening of banana. Similarly, in mango, glycanases such as mannanase, galactanase and arabananase were recognised as the key enzymes for textural degradation. There was a major drop in molecular weights of carbohydrate polymers during ripening of mango with the complete disappearance of low molecular weight polysaccharides of below 70,000 daltons. This information is useful for monitoring, at the biochemical level, the textural loss during ripening of banana and mango without inhibiting ethylene-associated natural ripening.