Effect of Drying Methods on the Chemical, Pasting and Functional Properties of Unripe Plantain (Musa paradisiaca) Flour

Abstract

Aims: The effect of different drying methods on the chemical, pasting and functional properties of unripe plantain flour was evaluated in this study. Study Design: Research study. Place and Duration of Study: This study was carried out in the Food Chemistry and Food Processing Laboratories of the Department of Food Technology, Federal Polytechnic Ado-Ekiti, Ekiti State between October 2013 and April 2014. Methodology: Equal quantity of unripe plantain pieces of the same dimension was subjected to four different drying methods: hot air oven (70°C), tray dryer (70°C, 1.5 m/s), fluidized bed dryer (70°C, 2.75 m/s) and sun drying until constant weight was obtained. The resulting samples were pulverized and then subjected to chemical, pasting and functional analysis. Results: Hot air oven was the most effective in drying the unripe plantain to the lowest moisture content of 3.24%, the moisture content of unripe plantain dried with tray dryer was the highest (5.43%). The protein and ash contents of the unripe plantain dried with hot air oven; fluidized bed dryer; tray dryer and sun drying were 3.82% and 3.11%; 3.07% and 3.14%; 3.21% and 3.91%; 3.04% and 3.56% respectively. The pH and energy value of the four samples were in the range of 5.70 – 6.20 and 3.68 – 3.83 Kcal/g respectively. The peak and final viscosities of the unripe plantain dried with hot air oven; fluidized bed dryer; tray dryer and sun drying were 166.25 RVU and 293.33 RVU; 119.67 RVU and 126.50 RVU; 163.17 RVU and 243.58 RVU; 239.83 RVU and 124.33 RVU respectively. The water absorption capacity, oil absorption capacity and swelling power of samples dried with hot air oven; fluidized bed dryer; tray dryer and sun drying were 160 ml/100 g, 195 ml/100 g and 3.58; 160 ml/100 g, 200 ml/100 g and 3.65; 180 ml/100 g, 165 ml/100 g and 3.22; 130 ml/100 g, 210 ml/100 g and 3.05 respectively. Conclusion: Oven and fluidized bed drying provided better alternatives to the traditional natural sun drying of unripe plantain especially in terms of final viscosity, peak viscosity, breakthrough viscosity; chemical and functional  properties.