Development of a Motorized Hydraulic Press for Sesame (Sesamum indicum L.) Oil Expression

Sesame oil is edible and of high economic and medicinal potentials. However, its expression from the seeds is still largely done manually which is tedious and inefficient. The few imported mechanical oil presses are prone to incessant breakdown and costly. A motorized hydraulic press for sesame oil expression was designed, fabricated and tested. The major components of the machine include a hydraulic cylinder, hydraulic pump, two-way control valves, heater band with temperature controller, stopper plate, electric motor and the frame. Paste of ground sesame seeds wrapped in a cheese cloth was forced against a stopper end plate on the expression barrel whose temperature is controlled in order to get the oil expressed out. The machine performance was evaluated using two levels of seed conditions (roasted (RS) and unroasted (URS)) at three levels of moisture contents (6, 9 and 12% wet basis) and four levels of temperature (70, 80, 90 and 100ºC). The performance indicators investigated included: throughput capacity, percentage oil yield, percentage expression efficiency and cake recovery efficiency. Results of tests showed that the highest percentage oil yield of 33.3% was recorded when sesame seed was roasted, milled and pressed at a moisture content of 6% and expression temperature of 90ºC.  Also the highest expression efficiency was recorded as 69.4% when the seed was roasted, milled and pressed at a moisture content of 6% and temperature of 90ºC. The highest cake recovery was recorded as 74% when the sesame seed was milled without roasting at a moisture content of 12% and temperature of 70ºC. The oil press would assist in the growth of indigenous edible oil production industry

Nano-Rheological Behaviour of Cassava Starch-Zinc Nanocomposite Film under Dynamic Loading for High Speed Transportation of Packaged Food

This research was undertaken to determine the nano–rheological behaviours of cassava starch–zinc–nanocomposite films under dynamic loading for assessing their suitability as food packaging materials in high speed transportation. The films, with thickness ranging between 15 ± 0.22–17 ± 0.13 µm, were prepared by casting mixtures of 24 g cassava starch, 45–55% (w/w) glycerol and 0–2% (w/w) zinc nanoparticles in plastic moulds of 8–12 mm depths. The effects of the nanoparticles, thickness and glycerol on the rheological properties of the films, including the Young’s modulus, creep, hardness and plasticity index were determined using nanoindentation technique. The results show that the Young’s modulus and hardness of the films varied inconsistently with glycerol concentration and nanoparticles due probably to their isotropic nature and sensitivity to slight change in load. The plasticity index was lower for 15 µm film, which absorbed 40 pNm and dissipated 0.5 pNm during loading and unloading stages, respectively. The response of the 15 µm film to creep was higher than 16 µm and 17 µm films, and this may be consequence of lower wear at higher loads. This implies that the nanocomposite film might be suitable for high speed transportation of packaged food

DETERMINATION OF SOME ENGINEERING PROPERTIES OF CASSAVA TUBERS GROWN IN NORTHERN NIGERIA

Several cassava processing operations have been mechanized successfully, but cassava peeling is still largely carried out manually; however, in this work some selected engineering properties of 5 cassava varieties mostly grown in northern part of Nigeria were determined to provide basic data for the design of cassava peeling machine. These properties include thickness of the peel, the length, and axial dimensions - major, intermediate and minor diameter and the Strength of peel (peeling force), and Bioyield(breaking force).  The average length of the tubers measured are in the range of 15.4 – 68.51 cm while the maximum and minimum thickness of the peel are 6.01 and 0.54 mm respectively. The peel reduces in thickness from the radicle towards the apex and the larger the diameter of the tuber, the thicker the peCassava peelingel. The highest and lowest values of the peeling force are 2248 kN/m2 and 401 kN/m2respectively.  It was observed that the peeling force value increases and reduces along the length of the tuber. Also the peeling force reduces with time after harvest and has the highest value at 24 hours after harvest. This could be due to the deterioration of the tuber with time. The major, minor and intermediate diameters of the tubers determined are in the range of 3.00 –10.35 cm, 2.15 – 10.05 cm and 0.87 – 6.04 cm respectively.  The maximum bioyield force was 3880 kN/m2 and minimum was 769.3 kN/m2. All these are important in the design of a cassava peeling machine