Anthony Opoku

Drying and Color Characteristics of Coriander Foliage Using Convective Thin-Layer and Microwave Drying

Heat sensitive properties (aromatic, medicinal, color) provide herbs and spices with their high market value. In order to prevent extreme loss of heat sensitive properties when drying herbs, they are normally dried at low temperatures for longer periods of time to preserve these sensory properties. High energy consumption often results from drying herbs over a long period. Coriander (Coriandrum sativum L., Umbelliferae) was dehydrated in two different drying units (thin layer convection and microwave dryers) in order to compare the drying and final product quality (color) characteristics. Microwave drying of the coriander foliage was faster than convective drying. The entire drying process took place in the falling rate period for both microwave and convective dried samples. The drying rate for the microwave dried samples ranged from 42.3 to 48.2% db/min and that of the convective dried samples ranged from 7.1 to 12.5% db/min. The fresh sample color had the lowest L value at 26.83 with higher L values for all dried samples. The results show that convective thin layer dried coriander samples exhibited a significantly greater color change than microwave dried coriander samples. The color change index values for the microwave dried samples ranged from 2.67 to 3.27 and that of the convective dried samples varied from 4.59 to 6.58.

Mechanical Properties of Timothy Hay Node

The mechanical property of timothy hay node was investigated using the Instron testing machine. Unbaled first cut timothy hay of the 2007 crop year was used in the test. Before testing, the stem segments with nodes were equilibrated to moisture contents of 12.19 and 14.13% w.b.. According to its position in the hay stalk, the nodes on each stem were designated as top, middle, or bottom node. The nodes were then separated from the stalk and shaped in cylindrical form using a Dremel cutter. Using the Instron universal testing machine, the force-deformation relationship of the nodes as affected by the node position in the stem, node size, and moisture content was obtained under a constant rate of deformation of 1 mm/min. The Hertz’s theory for convex bodies was employed for calculation of the apparent modulus of elasticity and maximum contact stress of the timothy hay node. The apparent modulus of elasticity and maximum contact stress values increased with node moisture content and decreased with size and its position in the stalk. However, moisture content did not affect mechanical values with respect to nodes with size of >2.00 mm and bottom nodes.

DESIGN, EXPERIMENTAL AND ECONOMIC EVALUATION OF A COMMERCIAL-TYPE SOLAR DRYER FOR PRODUCTION OF HIGH-QUALITY HAY

Abstract Design features, development, experimental functional performance and economic evaluation of an energy efficient solar energy dryer for commercial production of high-quality hay and processed forage products are presented. The solar hay dryer consists of an improved solar collector with selective coated aluminum absorber plate and spaced fins, and a drying shed connected to the collector by an insulated duct and having a perforated metal grate floor, swing-away plywood frames and polyethylene curtains for effectively sealing the hay stack, and a crawl space below the floor where a 3-hp in-line centrifugal fan is housed for air circulation by suction. In late August and in early September, 1996, 160 small rectangular bales of alfalfa hay with about 25% bromegrass were successfully dried from 33% initial moisture content to 13%, and from 25% to 11% moisture in 4 and 3 days, respectively, under average weather conditions in Saskatoon, Saskatchewan, Canada. With about 18 m3/min per tonne airflow, 10-...

Pelleting Wheat-Based Distiller’s Dried Grains with Solubles: Quality Characteristics

The rapid expansion of ethanol processing plants in Canada has resulted in increased production of wheat-based distillers dried grains with solubles (DDGS). The transportation of the granular DDGS is becoming expensive and flowability of the material might be restricted during unloading due to caking. These have necessitated the need to pellet the granular DDGS before transportation. The possibility of pelleting wheat-based DDGS was investigated by using two die sizes 6.4 (1/4) and 7.9 mm (5/16 in.) with steam addition and without steam addition. A 1.5 kW (2.0 hp) CPM (California Pellet Mill Co., Crawfordsville, IN) CL-5 laboratory pellet mill was used. Moisture content, bulk density, durability and throughput of the DDGS pellets were determined. Proximate analysis of the samples was done. The results show that the values of crude protein, neutral detergent fibre and acid detergent fibre ranged from 37.37% to 40.33%, 51.04% to 51.87%, and 15.78% to 22.93%, respectively. It was possible to pellet the wheat-based DDGS by using different die sizes, with steam addition and without steam addition. The bulk density of the DDGS pellets ranged from 436.8 to 528.9 kg/m3. The durability of the DDGS pellets ranged from 60.3% to 92.7% with a throughput range of 45.52 to 68.77 kg/h. The die size and steam addition had a significant effect on the bulk density and the durability of the DDGS pellets. Pelleting the DDGS with a die size of 1/4 in. and with steam addition produced the highest pellet bulk density and durability values compared to the other tests (5/16 in. die with or without steam addition)

Thermal Properties of Timothy Hay

A dual thermal probe consisting of a thermal conductivity probe and thermal diffusivity probe was used to determine the thermal properties of timothy hay at different moisture contents (7.7%, 14.4% and 17.1% w.b.), temperatures (-17.76oC, -5.23oC, 5.16oC, 23.55oC and 60.13oC) and bulk densities (110, 184 and 275 kg/m3). Specific heat of timothy hay was measured using the method of indirect mixtures. The mean thermal conductivity of the timothy hay ranged from 0.0284 to 0.0605 W m-1 C-1. The thermal conductivity values increased with increasing temperature, moisture content and bulk density. The mean thermal diffusivity of the timothy hay ranged from1.042*10-7 to 3.031*10-7 m2/s. The thermal diffusivity timothy hay had a nonlinear relationship between temperature, moisture content and bulk density. The measured specific heat varied from 2.31 to 5.17 kJ kg-1 oC-1 for a moisture content range of 7.7 to 21.7%. The measured specific heats were higher than the calculated specific heats at similar moisture contents and temperature. The mean of the calculated specific heat of the timothy hay varied from 490.8 to 3988.4 J kg-1 oC-1. The specific heat values increased with increasing temperature and moisture content. However, the specific heat decreased with increasing bulk density.

Effect of Moisture Content, Postharvest Treatment and Storage Time on Physical Properties and Dehulling Quality of Red Lentil

Red lentil of three initial different moisture contents of 9.62%, 10.07%, 11.31% w.b., was stored for 2 months after different postharvest treatments, including storage at two temperatures of 5 ℃ and 25℃ and storage at 5℃ after three freezing and thawing cycles. The physical properties and dehulling quality were investigated at monthly intervals during the 2-month storage period. The major axis, minor axis, thickness, total perimeter, total area were from 4.689 to 4.545 mm, 4.329 to 4.219 mm, 2.206 to 2.252 mm, 15.055 to 15.560 mm and 15.440 to 14.748 mm, at a moisture content of 9.62% w.b., respectively, during 2-month storage period. At the above moisture range, the static coefficient of friction increased linearly against various surfaces, namely, concrete, wood, rubber and stainless steel, while the dehulling efficiency noticeably decreased. Under different postharvest treatments, the bulk density, particle density, and porosity for the red lentil stored at 25℃ and under the freezing and thawing cycles increased within the storage period, while these properties for the red lentil stored at 5℃ decreased within the storage period. The results are necessary for designing

Crushing force, deformation modulus and crushing strength of timothy hay nodal stem segments

To disinfest timothy hay bales of Hessian fly puparia (Mayetiola destructor (Say)), mechanical compaction should be able to crush the hay stem node in order to destroy the puparia located near it. The Instron testing machine was used to determine the maximum crushing force, modulus of deformation and the crushing strength of nodal stem segments. The tests were done at crosshead speeds of 5, 15 and 25 mm/min. The hay samples used had moisture contents of 10.7%, 13.7% and 17.6%. The maximum crushing force, deformation modulus and the crushing strength of the timothy hay stem segments increased with increasing width of the hay node after compression. Increasing the crosshead speed increased the crushing force, deformation modulus and the crushing strength. The crushing force, deformation modulus and the crushing strength decreased with increasing moisture content. The average maximum crushing force ranged from 1.4570 to 2.3583 kN, with a SD range of 0.4112 to 0.7459 kN. The average deformation modulus of the timothy hay stem segments varied from 3075 to 4103 N/mm, with a SD range of 443 to 756 N/mm. The average maximum crushing strength of the stem segments ranged from 11.24 to 19.52 MPa, with a SD range of 1.82 to 3.55 MPa.

Effect of microwave drying on grinding and particle size distribution of green field pea

Field pea (Pisum sativum) is a good source of protein and energy. It has found wide uses in swine, poultry, ruminants and aquaculture feed rations. To mix with other ingredients before feeding to livestock or pelleting, feedstuffs must be ground. Energy requirement to grind feedstuffs depends on their physical and mechanical properties, drying method and drying temperature. Field pea samples were dried using microwave and convective dryers to various moisture contents. The dried, as well as original (as-is) samples were ground using a hammer mill. Two screen sizes (1.59 and 3.18 mm) were used. The grinding throughput rate, specific energy, geometric mean particle diameter (dgw) and the geometric particle standard deviation (Sgw) of the samples were determined. For the microwave dried-field peas which were ground with 1.59 mm screen size, the dgw ranged from 187.0 to 218.0 µm and the specific energy consumption varied from 13.92 to 19.38 kWh/t. For the microwave dried samples which were ground with a screen size of 3.18 mm, the dgw varied from 436.0 to 485.1 µm and specific energy ranged from 6.88 to 9.32 kWh/t. The field pea grinding throughput rate and the dgw decreased with increasing final moisture content, while the specific energy increased with increasing final moisture content, for both microwave and convective drying methods. For comparable moisture contents, ‘as-is’ field pea samples had higher dgw values compared to the dried samples.

Effects of post-harvest processes including pre-conditioning, drying and rewetting cycles and storage period on dehulling and cooking quality characteristics of red lentils

Red lentil (Lens culinaris Medikus), an important pulse crop produced in Western Canada, is mainly consumed as split or whole cotyledon (“football”) after the seed coat has been removed through dehulling. However, related information on the effects of storage time, postharvest treatments and storage temperature on the dehulling efficiency and cooking quality of red lentils at different moisture contents are not readily available for processors, marketers, breeders, as well as growers. The objective of this study is therefore to investigate the effect of storage temperature, postharvest treatments and storage time on the dehulling efficiency and cooking quality of red lentil. While a laboratory Satake dehuller was used to evaluate the dehulling characteristics of red lentil, an automated Mattson cooker was used to determine the cooking quality. Red lentil of ‘Robin’ variety for 2007 harvest with moisture contents of 10.07%, 11.31% and 13.27% w.b., as well as ‘Robin’ samples for 2008 harvest of moisture contents 10.13%, 11.52% and 13.37% were kept in storage at two temperatures of 5oC and 25oC. In addition, samples with the moisture contents of 10.07%, 10.13%, 13.27% and 13.37% were subjected to three freeze-thaw cycles and stored at 5oC only. Similar treatments were given to lentil samples of ‘Impact’ variety with moisture contents of 10.21%, 11.56%, and 13.14% w.b. for 2007 harvest and 10.33%, 11.48% and 13.54% for 2008 harvest. In addition, lentil sample of ‘Impact’ and ‘Robin’ varieties at 13.14% and 13.27% (w.b.) moisture contents for 2007 harvest as well as 13.54% and 13.37% moisture contents for 2008 harvest respectively were further reconditioned to a moisture content of 18% (w.b.). As part of the postharvest treatment, these samples were dried at near ambient temperature and at 80°C under forced convention (simulating extreme drying conditions) to two final moisture contents of 10% and 13%. These samples were further stored at 5°C and 25°C. Dehulling efficiency and cooking quality were determined after 1 and 6 month storage. Also, lentil sample (2007 harvest) of ‘Impact’ variety at 10.21% and 13.14% as well as ‘Robin’ variety at 10.07% and 13.27% moisture contents were subjected to 5 cycles of drying and rewetting in the range of ±2% from its nominal moisture and tested for quality (dehulling efficiency and cooking quality) after 1 and 2 months storage at 5°C. This same postharvest treatment was given to lentil sample (2008 harvest) of ‘Impact’ variety at 10.33% and 13.54% moisture contents as well as ‘Robin’ variety at 10.13% and 13.37% moisture contents. Tests on dehulling efficiency and cooking quality were conducted at specific time intervals. Generally, there was a decrease in the dehulling efficiency values of ‘Robin’ and ‘Impact’ lentil samples with storage time up to 12 months for both harvest years (2007 and 2008). Among the postharvest treatments considered in this study, the drying and rewetting of lentil samples (‘Robin’ and ‘Impact’) had the most significant impact on dehulling efficiency. For other postharvest treatments, the trends were not consistent. In some cases dehulling efficiency increased for samples dried at 80°C, but observations like this were not consistent for other variety. Generally, storage time did not affect the cooking time values of ‘Robin’ and ‘Impact’ lentil samples. This is true for samples stored at 5°C, 25°C and 5°C subject to freeze thaw cycles, and also those subjected to other postharvest treatments at different moisture contents. Drying and rewetting of ‘Robin’ and ‘Impact’ lentils significantly increased the cooking time of these samples.

The Creep Properties of Timothy when Compressed to High Density

Fibrous biomaterials can be utilized for different applications. Compression processing is a highly efficient way to reduce the transportation cost. Most biomaterials including agricultural fibrous materials exhibit viscoelastically when subjected to stress and strain. In this paper, the creep properties of timothy bales were investigate, when subjected to high pressure compression. To determine if material collapse during compression (failure?) has an effect on hay properties, tests were designed so that materials were tested in two lengths: original length and length less than 125 mm (5 in.). Moisture content was used as one of the experimental factors as well. It was found that cut hay’s creep properties were different from the original hay. The elastic and viscous coefficients for cut hay were lower than original hay in the same moisture level. Moisture also affected the elastic and viscous coefficients. Higher moisture lead to higher viscous coefficients but an opposite trend was observed on the elastic coefficient. Data from this investigation can be used by, researchers and equipment designers in designing a high performance compactor to increase the efficiency of industrial production.