Non-Enzymatic Darkening in Young Hot Water-Peeled Green Bananas

Abstract

When green bananas with a pulp to peel ratio of less than 1.3 are exposed to air after a hot-water treatment to inactivate the enzyme systems and to facilitate peeling, a dark discoloration appears on the exposed surface. This after-peeling darkening was cont rolled by dipping the peeled fruit in Na₂ EDT A solutions or blanching in 2% solutions of sodium acid pyrophosphate. Sulfitation in K₂S₂O₅ solutions had only a minimal effect in controlling the darkening reaction. Treatment with Na₂ EDT A did not control the after-peeling darkening due to an excessive sloughing of the surface tissue. Green bananas were found to have a higher iron content on the surface tissue prone to darkening than in the rest of the fruit, which suggests that the darkening reaction involves the formation of a color complex by reaction of iron and o-diphenols.