Control of Polyphenol Oxidase Activity in Banana Slices During Osmotic Dehydration

Abstract

The purpose of this study was to determine the effect of sodium metabisulfite and 4-hexylresorcinol on polyphenol oxidase (PPO) activity change in banana slices during osmotic dehydration in sucrose syrup.

From a previous study only three osmotic dehydration conditions were selected as the most adequate due to color change but also where PPO residual activity was still present after osmotic drying: T1 (60°Bx, 50°C, pH 6), T2 (60°Bx, 60°C, pH 8), and T3 (70°Bx, 50°C, pH 8). The level of sodium metabisulfite was varied from 100 to 1000 ppm and 4-hexylresorcinol from 10 to 100 ppm. The inner and outer parts of the banana slice were used for PPO activity determination at 302 nm with 4 methyl-catechol as a substrate.

During osmotic dehydration of a banana slice, PPO activity tended to decrease and residual enzymatic activity was still detected. Sodium metabisulfite concentration up to 200 ppm and 4-hexylresorcinol up to 50 ppm had no effect on PPO residual activity after 4 h of osmotic dehydration. Depending on the process conditions, a higher concentration of additives than these were necessary to control PPO activity during osmotic dehydration of banana slices.

Keywords:

• Drying
• PPO activity
• Tropical fruit