COMPARATIVE QUALITY CHARACTERISTICS OF PUPURU (A TRADITIONAL CASSAVA-BASED DOUGH MEAL) FROM THE BLENDS OF FRESH CASSAVA ROOTS AND DRIED CASSAVA CHIPS

Abstract

This study was aimed at investigating the quality characteristics of pupuru produced from the combination of fresh cassava roots and dried cassava chips. For dried cassava chips, cassava tubers were manually sorted, peeled, washed and cut into circular chips, blanched at 100 0 C (2 min), oven dried at 70 0 C, cooled to get dried cassava chips of 10.1% moisture content. For the production of pupuru flour, fresh cassava roots were manually peeled, washed and soaked in water for four days (4 days) for fermentation to take place, the steeping was done in different proportions using two soaking methods. Method 1: soaking of fresh roots and dried chips with cold water throughout the 96-hours duration with 24-hourly water replacement. The Fresh cassava roots and dried chips used (on dry weight basis) were 100, 25:75, 50:50, 100% respectively. Method 2: initial soaking of fresh roots and dried chips with hot water followed by 24-hourly replacement with cold water for a total of 96 hours. The fresh roots and dried chips used (on dry weight basis) were 25:75, 50:50, and 100% respectively. After the soaking period, the fermented mass was subjected to draining, removal of fibrous materials, coarse grating, dewatering, sifting, toasting, cooling and milling to obtain the pupuru flour. The pupuru flour and the re-constituted dough meal were subjected to various analyses including physicochemical properties, pasting properties, rheological properties, colour characteristics, in vitro starch digestibility and sensory properties. The fresh cassava roots have 65.25% moisture content, 10.9 mg/kg cyanide content and pH 6.21%. The dried cassava chips have 10.1% moisture content, 3.5 mg/k cyanide content and pH 5.80. The pupuru flour have moisture content of 3.37-8.23%, the pH 4.05-4.78 and hydrogen cyanide (HCN) value 1.1-2.2mg/kg. The water absorption capacity (4.08-4.66 g/g), bulk density (0.63-0.84 g/ml), swelling index (35.94-50.89%) of the pupuru flour increased with the percentage of fresh cassava roots and decrease in the percentage of dried cassava chips. The pasting variables were found to increase with the percentage of fresh cassava roots and dried cassava chips in the combination and these include sample A1F (4140 RVU) with highest the peak viscosity while sample D2F (245 RVU) has the lowest peak viscosity, sample A1F (190 RVU) with highest breakdown viscosity while sample C1F (10 RVU) has the lowest breakdown viscosity, sample A1F (5313 RVU) has highest final viscosity while sample D2F (418 RVU) has the lowest final viscosity. The rheological properties of re-constituted pupuru doughmeal revealed sample C1F (3962.522 N) with highest load at peak compressive force while sample B2F (73.03 N) has the lowest load at peak compressive force, stress at peak compressive force with sample C1F (1.378 mPa) has highest while sample D1F (0.025 mPa) has the lowest. Sample A1F (47.30%) has the highest value while sample D2F (33.66%) has the lowest value for in vitro starch digestibility. The sensory quality rating of re-constituted pupuru doughmeal showed that the food product obtained from sample C1F (50%fresh cassava roots: 50% dried cassava chips; dry weight basis; with cold water soaking for 96hour combined with 24-hourly water replacement) was rated the highest followed by sample C2F (50%fresh cassava roots: 50% dried cassava chips; dry weight basis; with initial hot water soaking followed by 24-hourly cold water replacement) in terms of mouldability, aroma, colour and overall acceptability among the blends of fresh cassava roots and dried cassava chips. The implication of this study is that in an event of scarcity of fresh cassava roots or low supply, the preparation of pupuru (a traditional cassava-based doughmeal) from the blend of fresh cassava roots and dried cassava chips is feasible.