Effect of different drying methods on the properties of banana (Musa spp. AAA-EA) flour.

Abstract

This study evaluated the effect of different drying methods on the nutritional composition and functional properties of East African Highland Cooking Bananas (Matooke) flour. Two varieties of Matooke; Kibuzi and Mpologoma were studied. Conventional oven, microwave, infrared and solar drying methods were studied. The nutritional composition, as well as the functional and pasting properties of the flours, were determined. Microwave drying had the highest drying efficiency with the shortest drying time of 30 min at 200W and 18 min at 400W. An increase in microwave power (200W to 400W) resulted in a 40% reduction in drying time. Drying by infrared (850W) and solar drying took 30 and 240 min, respectively. Drying in the conventional oven dryer took 240 and 60 min at 60°C and 70°C, respectively. Increase in drying temperature from 60-70oC resulted in a 70% reduction in drying time. Microwave flour dried at 400W had the lowest final moisture content (0.37% for Kibuzi and 0.56% for Mpologoma) and infrared drying had the highest (5.16% for Kibuzi and 4.11% for Mpologoma). The different drying methods had varying effects on the proximate composition and functional properties of the Matooke flour. The dry matter ranged between 89.0-92.0%, crude protein 5.01-10.24%, crude fat 0.18-1.79%, dietary fiber 0.77-2.74%, carbohydrates 73.6-81.0% and ash 3.97-4.91%. Solubility values ranged from 15.6-21.1 g/100g, swelling power values ranged from 9.6-15.7 g/g, OAC 0.58-0.73 g/g, WAC 0.9-1.9 g/g, and WHC 110.5-243.7 g/100g. Solar-dried flour had the highest peak viscosities while microwave-dried flour had the lowest. Solar and conventional oven dried flours had higher breakdown viscosities as compared to microwave and infrared dried flours. The Matooke flour produced can be used as a functional ingredient in food formulations.