Numerical and Experimental Studies on the Cutting Energy Requirements of Okra (Abelmoschus esculentus L.)

Cutting energy requirements for vegetable crops is a prerequisite in the engineering design of appropriate cost effective cutting systems consuming minimum amount of energy while still providing high quality products. This study attempts the development of predictive equations describing the cutting energy for okra (Abelmoschus esculentus L.). Dimensional analysis based on the Buckingham pi theorem was used to obtain the functional relationship between the cutting energy of the selected vegetable and the independent variables such as tool weight (w), height of tool drop (Hd), tool edge thickness (t), cutting speed (v), crop size (s), crop moisture content (φ), crop contact area (A) and crop density (σ). The developed model was validated with experimental data. A high coefficient of determination of R2 value of 0.973 between the predicted and measured energy values showed that the method is good. Hence the obtained predictive model is appropriate for determining the cutting energy requirements of okra up to 97%

Numerical and Experimental Studies on the Cutting Energy Requirements of Okra (Abelmoschus esculentus L.)

Cutting energy requirements for vegetable crops is a prerequisite in the engineering design of appropriate cost effective cutting systems consuming minimum amount of energy while still providing high quality products. This study attempts the development of predictive equations describing the cutting energy for okra (Abelmoschus esculentus L.). Dimensional analysis based on the Buckingham pi theorem was used to obtain the functional relationship between the cutting energy of the selected vegetable and the independent variables such as tool weight (w), height of tool drop (Hd), tool edge thickness (t), cutting speed (v), crop size (s), crop moisture content (φ), crop contact area (A) and crop density (σ). The developed model was validated with experimental data. A high coefficient of determination of R2 value of 0.973 between the predicted and measured energy values showed that the method is good. Hence the obtained predictive model is appropriate for determining the cutting energy requirements of okra up to 97%

Analytical development of bird pecking force equation for a self-metering poultry feeder

The concept of a self-metering poultry feeder was developed.  The theoretical analysis of the forces involved in its operation was done and a generalized pecking force model was developed.  Mathematical expressions, logical assumptions, graphical relations and models as well as statistical analyses were adopted in the pecking force analysis. This pecking force relates to some design parameters like feed flow rate, hopper aperture, etc. The generalized equation was tested using a fabricated model of the equipment.  Experimental results show that the equation can be used to predict the performance of the machine reasonably and also the level of satiety and bird vigor determine the amount of pecking force which was described by a polynomial regression relationship (of the 4th order with R2 > 0.9) which increases with increasing aperture opening with time of feeding by different ages of birds. The pecking force reached 10N for <8 weeks birds after about 40 minutes for the highest aperture opening. For the three sample categories of birds, the pecking force was consistently lower with the smallest aperture Ca1 and highest with aperture Ca3. Quantity of feed consumed decreased with feeding time in a power regression relationship and the birds, irrespective of the ages had a feel of satiety after 50 minutes of feeding with feed consumed being less than 0.1g. The general performance of each category of bird is a function of their age and number, vigor and pecking action

Production Optimization of Fortified Foam-Mat Dried Yoghurt

This experimental study examines the effect of different production parameters such as moringa seed flour, ginger extract, forming agent, mixing time and drying temperature on the selected proximate and microbiological qualities of foam-mat dried yoghurt. The design and analysis of the experiment were conducted with the central composite design technique of the Design Expert statistical software. The study aimed at fortifying and optimizing the production of foam-mat dried yoghurt, which involves powdered milk, water, starter culture and flavour which are kept constant and followed by the addition of moringa seed flour, ginger extract and forming agent (egg white). Twenty-five experimental runs with the control experiment inclusive were carried out based on the mixture-process design matrix and the nutritional properties evaluated include moisture content, crude protein, fat content, ash content, carbohydrate content, total lactic acid, bacteria and fungi. Numerical optimization, via the desirability approach, was utilized to determine the optimum production parameters for the fortified foam-mat dried yoghurt. Graphical optimization was also used to display the prediction of all responses in the mixture-process factors space. Results got revealed that foam-mat dried yoghurt with 10.79 % moisture content, 12.115% crude protein, 0.552% ash content, 2.196% fat and 16.409% carbohydrate could be produced from 80% of fresh yoghurt, 5.466% of moringa seed flour, 7.534% of ginger extract, 7% of foaming agent, mixing duration 2.53mins, drying temperature at 50oC and 0.721 desirability index gave the optimum quality. The results of this work are of great use to the food and beverage industries as they provide a basis for selecting process parameters for optimal foam-mat dried yoghurt production. Prospects for more studies were suggested

Effect of Loading Rate on Viscoelastic Behaviour of Cassava Roots (Manihot Esculenta Crantz) in Bending

The effect of loading rate on the viscoelastic response of cassava roots, at a moisture content of 52.13 ± 5.74% (w.b.), to applied bending forces was studied. Experiments were conducted using a modified Instron Testing Machine (ITM) of 1 kN capacity, to investigate both creep and stress relaxation (viscoelastic) behaviour of cassava roots (variety TME 419) when static bending forces were applied at mid-span with loading rates of 2.7, 4.2, 5.3, 7.45, and 9.9 mm min-1. The creep behaviour indicated that the creep compliance may be described using a 4-element model consisting of Maxwell and Kelvin models in series. The retardation time and the instantaneous creep compliance of cassava root were found to be 25.5 s and 0.03009 (N mm-2)-1, respectively. The stress relaxation behaviour could be represented using a 2-element Maxwell approach with a parallel-orientated spring. The relaxation times are 20 and 500 s, for the range of the loading rates. Relaxation modulus was found to be a function of the degree of loading, rising as the degree of loading intensified and decreasing with time. As the loading rate increased from 2.7 – 9.9 mm min-1, the relaxation modulus increased from 1.25 – 6.89 N mm-2. The result of this study gives an idea of the food product attributes vis-à-vis its strength characteristics to mechanical damage. It guides the food process engineer in estimating the impact of stress on cassava roots during postharvest operations for optimum design of efficient cassava peeling machines and product storage quality. Prospects for further work were stated. &nbsp

ENERGY ANALYSIS AND OPTIMIZATION OF THIN LAYER DRYING CONDITIONS OF OKRA

This paper presents the energy analysis and optimization of thin layer convective hot air drying conditions of okra slices in a hybrid solar-electric crop dryer based on the specific energy consumption and drying duration using response surface methodology (RSM). Fresh sliced okra samples (Abelmoschus esculentus) of 900g batch size were dried from initial to final desired moisture contents of 87.8 to 0.5% (wb) respectively. The Box-Behnken approach of Design Expert 7.0 statistical package was used to illustrate the effects of the varying levels of the drying parameters: drying air temperature (50, 60 and 70oC), air velocity (1, 1.5 and 2ms-1) and sample slice thickness (10, 15 and 20mm) on the drying duration and specific energy consumption of okra slices. All responses were fitted into a second order polynomial model and R2-values > 0.959 were observed in all treatment combinations. Suitability of the developed predictive response models was verified and validated with statistical analyses of the process parameters, experimental data, normal % probability plots, as well as simulated versus experimental data plots. Results obtained showed that the maximum and minimum mean energy consumptions were 69.02kWh and 2.02kWh, respectively. Regression models of specific energy consumption for each slice thickness were developed and their respective R2 compared. Thermal utilization efficiency of okra slices were in the range of 11.1 to 38.8%. The energy efficiency varied in the range of 11.2 to 45.6%; whereas the drying efficiency ranged between 28.1 and 49.6%. The desirability index technique was used to predict the optimum drying condition. The best drying conditions of 59.81oC, 2ms-1 and 10mm air temperature, air velocity and slice thickness, respectively were obtained. The corresponding predicted response values of 94.54mins and 3.54kWhg1 were obtained for drying duration and specific energy consumption, respectively. The results from this study make available to food industries the optimized drying conditions for better quality dried okra slices as well as improve the dryer energy efficiency and reduce cost of drying operation