Effect of drying temperature on the nutritional quality of Moringa oleifera leaves

Abstract

Moringa oleifera leaves are generally consumed in the dry powdered form. Therefore, this research was carried out to investigate the effect of temperature on the nutritional quality of M. oleifera leaves powder. The leaves were dried under the shade at 30°C for two weeks and in the oven at temperature range from 40 to 70°C for 2 h. The results show that temperature affects nutrient composition of the leaf powder. As the drying temperature increased, crude protein decreased significantly (p≤0.05). The samples from shade drying had protein content value of 28.44 g/100 g, while samples those dried at 70°C had 19.89 g/100 g. Similar trends were observed for fat content which was 2.69 g/100 g for shade drying and 2.46 g/100 g at 70°C. The ash, fibre and carbohydrate contents of leaf powder increased with drying temperature. Samples from shade drying had 4.55, 16.33, and 32.75 g/100g for ash, fibre and carbohydrate respectively. However, the amounts of ash, fibre and carbohydrate increased significantly to 5.20, 17.66 and 52.30 g/100 g, respectively when dried at 70°C. The beta-carotene which is the precursor of vitamin A significantly (p<0.05) decreased from 5,220.20 mg/100 g in shade dried leaves to 4,946.20 mg/100 g in oven dried at 70 °C. Vitamin C content decreased slightly from 27.39 mg/100 g for shade dried to 25.70 mg/100 g, dried at 70°C. The minerals investigated generally showed significant increase with temperature. In general, the nutritional parameters of M. oleifera leaves dried in the shade varied closely with those dried in the oven at 40 and 50°C for 2 h. Key words: Moringa oleifera, drying, temperature effect, nutritional quality.