Abstract

This study examined the effect of blanching (60°C; 10 min) followed by drying (50 - 80°C) and rehydrating at 100°C for 15 – 60 min on product characteristics (shrinkage, dry matter loss, moisture loss, electrical conductivity and rehydration capacity) of ripe and unripe banana samples. Increasing drying temperature resulted in greater moisture loss, higher shrinkage and higher rehydrating capacity with time. Changes in thickness were greater than the radial changes and mathematical equations gave a good fit when related to moisture content using a linear model. The electrical conductivity of the rehydrating solution increased as the initial temperature of drying increased and this resulted in greater dry matter loss, indicating greater loss of membrane integrity. Blanching improved moisture loss compared to untreated samples. The effect of product ripeness was not significant on product attributes (shrinkage, dry matter loss, moisture loss, electrical conductivity and rehydration capacity). Blanched samples had reduced ascorbic acid content.

Key words: Pretreatment, drying temperature, moisture loss, shrinkage, rehydration characteristics, electrical conductivity.