Abstract:
A study was undertaken to examine the influence of different processing methods on drying rate and quality of banana. The effects of processing methods such as blanching, chilling, freezing and combination treatments on the quality of bananas (Musa acuminata var. Williams) were investigated. The banana fruits were dried at 400C in a heat pump dehumidifier drier at the air velocity of 3.0 m/s until the final moisture content of 25% of dry weight was achieved. The drying rates of all treatments were high initially when the moisture content was highest then decreased rapidly. The blanched samples had the highest moisture content of 32.1% whereas the frozen fruit samples resulted in the shortest drying time of22.4 h compared to the other treätments. The drying rate of banana after application of freezing was found to be 0.099 kgkg-lh;l which was significantly (p<O.05) faster than those to which freezing was not applied. The level of total sugars, vitamin C and pH were significantly higher in the blanched fruits followed by the combined blanching and freezing treatment. The vitamin C content of the blanched sample was 35.9 mg/ 100g which was significantly the highest among the tested treatments. The results of the sensory evaluation revealed that the preference rating ofcolour of the samples subjected only to blanching was significantly@<0.05) higher than that of all the other treatments. Blanching and freezing of bananas before drying improved their overall acceptability as a result of inactivating the enzymes responsible for browning reactions. Blanching in combination with freezing was the most effective treatment in reducing the microbial load by the reduction of initial microbial count by thermal destruction and lowers the water activity by subsequent freezing. Combined blanching and freezing could be used as a processing method to produce high quality dried banana where there is an annual surplus production of bananas
