Proximate Composition, Antinutrient Content and Functional Properties of Soursop Flour as Influenced by Oven and Freeze Drying Methods

Abstract

The effect of Oven and freeze drying methods on the proximate composition, anti-nutrient and selected physical attributes of soursop flours were determined using standard methods. The fruit pulp was frozen at -30 and freeze dried at -40 for 72hrs while oven drying was performed at 70 for 48hrs. Oven drying significantly (p≤0.05) lowered the fat (7.30±0.23%), moisture (12.40±0.29%) and carbohydrate (40.70±0.12%) content of soursop flour while freeze drying significantly (p≤0.05) lowered the protein (18.72±0.10%), fibre (12.30±0.23%), ash (6.30±0.17%) and energy (212.704±0.10%) content of the flour. The oven dried flour had higher phytate (0.03±0.10%) and oxalate (0.03±0.00%) content while the freeze dried flour had higher tannin (0.52±0.00%) content. The physical attributes of the flours however revealed that the freeze dried flour significantly (p≤0.05) had higher values for viscosity (32.50±0.29%), water absorption capacity (57.30±0.17%), swelling index (50.10±0.06%), solubility (22.30±0.17%), oil absorption capacity (24.60±0.23%) and emulsion capacity (24.60±0.23%) while the oven dried flour had higher values for bulk density (421.20±0.12%) and foam capacity (25.30±0.17%). Freeze dried soursop flour had better physical attributes, lower nutrient and anti-nutrient content.