A.O. Raji

Shape representation of axi‐symmetrical, non‐spherical particles in discrete element simulation using multi‐element model particles

A new method of representing non‐spherical, smooth‐surfaced, axi‐symmetrical particles in discrete element (DE) simulation using model particles comprising overlapping spheres of arbitrary size whose centres are fixed in position relative to each other along the major axis of symmetry of the particle is presented. Contact detection and calculation of force‐deformation and particle movement is achieved using standard DE techniques modified to integrate the behaviour of each element sphere with that of the multi‐element particle to which it belongs. The method enables the dynamic behaviour of particles of high aspect ratio and irregular curvature (in two dimensions) to be modelled. The use of spheres to represent a particle takes advantage of the computational speed and accuracy of contact detection for spheres, which should make the method comparable in computational efficiency to alternative schemes for representing non‐spherical particles.

Parameters Affecting Milling Qualities of Undefatted Soybeans (Glycine max, l. Merill) (1): Selected Thermal Treatment

In the developing countries animal proteins are very expensive and cannot meet with the protein requirement of the current explosive population trend hence, supplementing with plant protein is pertinent. Soybean, which is widely consumed when processed to flour and flour products, is one of the best substitutes if properly processed. This study, therefore, aimed at establishing the best thermal treatment among the commonly used methods that will conserve the protein content of soy flour maximally, result in high flour yield and acceptability. Four different methods: Roasting (ROA), Extrusion (EXT), Boil and Sun Dry (BSD) and Boil and Oven Dry (BOD), were used to prepare samples from Tax 1448 soybean variety obtained from International Institute for Tropical Agriculture (IITA) and mixed variety obtained from market. The samples were milled in an attrition mill and the flours obtained were subjected to proximate, sieve and organoleptic evaluations. The results of the experiment, showed a protein content of 40.5, 40.7, 40.1 and 40.3%, flour yields of 32.0, 3.7, 29.7 and 37.9%, and acceptability of 58.0, 61.0, 36.0, and 48.0% and protein content of 33.7, 34.4, 32.7 and 32.7%, flour yields of 17.0, 5.0, 14.1 and 12.3%, and acceptability of 64.0, 68.0, 48.0 and 60.0% for BOD, EXT, ROA and BSD respectively for Tax 1448 and mixed variety. These results indicated that BOD is a better method over others. EXT, though, has the highest acceptability and protein contents, these values (p < 0.05), have no significant difference from those of BOD. EXT however has a very low flour yield. This study has therefore established that BOD is the best of the commonly used domestic methods for producing acceptable soy flour of high protein content and flour yield.

Mathematical Modelling of Thin Layer Dried Cashew Kernels

ABSTRACT In this paper mathematical models describing thin layer drying of cashew kernels in a batch dryer were presented. The range of drying air temperature was 70 – 110°C. The initial moisture content of the cashew kernels was 9.29% (d.b.) and the final moisture content was in the range of 3.5 to 4.6% dry-basis. Seven different thin layer mathematical drying models were compared according to their coefficients of determination (R2) mean square error (MSE) and mean relative deviation modulus (P) to estimate drying curves. The effects of the drying air temperature and time on the drying model constants and coefficients were predicted by multiple regression analysis using linear and non-linear type models. The results have shown that among the models, the Page model was found to be the best for describing the drying behaviour of cashew kernels with R2, MSE and P values of 0.9830, 0.00311 and 5.046 respectively.

Optimisation of Cassava Pellet Processing Method

Processing cassava onto pellets, an internationally acceptable and commercially rewarding cassava product minimizes quantitative and qualitative losses. Pellet samples were produced through the conventional chipping, drying, milling then pelleting with and without steaming (CDMP-S and CDMP) and modified process of grating, dewatering then pelleting and steaming (GDWP-S). Investigations for storageability, durability, uniformity in dimension and nutritional qualities resulted in pellets with moisture content of 9%, uniformly light brown in colour, free from objectionable odour with no sign of deterioration after 90 days of storage. The durability index and fine formations are 99.8% and 0.2%, 98.8% and 1.2%, 99.4% and 0.6% for CDMP-S, CDMP and GDWP-S respectively. The average lengths of 2.81, 2.23 and 2.74 cm and diameters 0.76, 0.73 and 0.67 cm respectively fall within the standard. The carbohydrate contents are 82.9%, 83.4% and 84.5% and cyanogenic glycosides contents of 14.18mg/100g, 14.32mg/100g and 10.13mg/100g respectively. The pellets produced from the modified process GDWP-S in addition to satisfying the standard colour code also conforms favourably well in terms of strength, durability and nutritional quality with the conventional CDMP-S and are better than the cold pellets from the conventional process CDMP. These are in addition to the reduction of about eight hours of chip drying operation in the modified process. This reduction in time and energy with associated quality products show that the modified process is a promising approach in the production of pellets acceptable in the export market.

Parameters Affecting Milling Qualities of Undefatted Soybeans (Glycine max, L. Merill) (2): Selected Physical Properties

Soybean protein is highly rich in the essential amino acid needed by human body. In the developing countries, its use will be more generally acceptable when converted to flour like wheat. This work focused on establishing the optimum conditions of some physical characteristics of soybean for high quality and acceptable soy flour. The characteristics studied for soybean samples subjected to heat treatment of boiling and oven drying were the effect moisture content (MC) and the hull thickness on the quality of the flours. Ten samples of Tax 1485 at different moisture levels ranging from 20.6% to 8.6% and five varieties (Tax 1440-1E, Tax 1740, Tax 1485, Tax 1456 and Tax 1448-2E) obtained from International Institute for Tropical Agriculture (IITA), having different hull thicknesses were used. Soybean with mixed varieties commonly found in the open markets was also used to compare the effects of MC on the studied parameters. Flours obtained from the samples milled in an attrition mill were subjected to proximate, sieve and organoleptic evaluations. The hull thickness was found to have no correlation with protein retention, acceptability and flour yield, but moisture content has a very significant effect on the qualities. Between moisture content of 20.6% and 8.6%, protein and acceptability reduced from 40.0% to 27.7% and 4.3 to 2.2 respectively while yield increased from 0.9% to 5.8%. Though protein was reducing with reduced MC, there was no significant difference (p<0.05) in protein retention between MC of 20.6% and 10.1% but it became significant at 9.4%. There was no significant difference in acceptability from 13.6% to 8.6% MC and between 8.9% and 11.0% MC for flour yield. Both Tax 1485 and mixed varieties followed the same trend only that they have different absolute values. The mixed varieties however had no significant difference in protein content between 19.8% and 10.2% MC. These results, therefore established that to obtain acceptable soyflour of high flour yield and protein content, moisture content of soybean after processing should be about 10% (dry basis).