Effect of Processing Methods on the Physicochemical, Antinutrient and Pasting Properties of Three Commonly Consumed Soup Thickeners in Nigeria

Abstract

The effect of processing methods on the physicochemical, functional, anti-nutrient factors and pasting properties of Mucuna sloanei (ukpo), Brachystegia eurycoma (achi) and Daterium microcarpum (ofor) were assessed using standard methods. Flour from these seeds were produced after boiling and soaking at different time intervals.  The moisture and ash contents of the three soup thickeners ranged between 5.58- 8.92% and 1.14-5.59% with sample B1 (achi boiled for 15 min) and C4 (ofor soaked for 48 h) having the lowest while sample B2 (achi boiled for 30 min) and C1 (ofor boiled for 15 min) having the highest. Crude Fat and fibre contents ranged from 2.90-10.95% and 1.30-14.39% with samples C1 and A1 (ukpo boiled for 15 min) as the highest respectively. Crude protein and carbohydrate contents of soup thickeners ranged between 9.19 -21.31% and 45.01-71.38% with samples A3 (ukpo soaked for 24 h) and B4 (achi soaked for 48 h) as the highest. Sugar and starch contents ranged from 2.61-5.04% and from 69.00-74.27% respectively with sample C4 and A4 (ukpo soaked for 48 h) as the lowest and sample A3 and B3 (Achi soaked for 24 h) as the highest. Amylose content increased with boiling and decreased with soaking which was the reverse amylopectin. Functional properties showed bulk density and dispersibility to range between 0.56-0.76 g/ml and 32.50-48-00% with sample B3 (achi soaked for 24 h) as highest in both cases. Solubility and swelling power ranged from 32.56-107.51% and from 4.61-8.72 g/g with sample A2 (ukpo boiled for 30 min) and A1 having the highest respectively. Foam capacity ranged from 2.50-29.50% with sample C2 (ofor soaked for 48 h) having the lowest and sample A1 having the highest, while the least gelation concentration of the three soup thickeners recorded 2.00% for all the treatments. Water absorption capacity ranged between 0.67-10.46 ml/g with B1 having the lowest and sample C2 having the highest. Antinutritional factors showed that phytate recorded 0.01 g/kg for all the treatments, tannin ranged from 2.22-40.71 mg/kg, oxalate between 3.40-7.90mg/100g and saponin between 2.60-9.18% with different treatments affecting the antinutrients. Free fatty acid, peroxide value, saponification and acid values increased with an increase in treatment time while iodine value decreased as processing time increased. Pasting result showed that treatment and time affected pasting properties with the highest values as peak viscosity 16429RVU, trough viscosity 9231RVU, breakdown 7858RVU, final viscosity 19977RVU and set back viscosity 13004RVU respectively. Peak time and pasting temperature ranged between 1.60-6.10 min and between 50.25-76.18°C for the different treatments. This study shows the need for appropriate treatment and time combination for better nutrient availability and detoxification of these seeds as soup thickeners.