Volume 6, Issue 2

Experiments were performed on a closed loop self-exciting mode oscillating flow heat pipe (SEMOS HP) with uniform and non-uniform structures under the same tested conditions. The heat transfer characteristics are analyzed by comparing the temperature of wall of the heat pipe and output power when the heat input of the electric heating board and heating position are changed. The result shows that the heat transfer rate could be improved by using a non-uniform structure under low or middle heat input, and it gives the highest heat transfer performance when the non-uniform diameter section is at the bottom of the heat pipe and the heating source located below the non-uniform section.

A rotary device was built in a home microwave oven, where wet soybean was dried in a dynamic moving state to improve the microwave drying uniformity. Experiments were conducted to investigate the relative water removal ratio which was defined to characterize the electromagnetic field distribution in microwave oven, and to compare the drying characteristics between static and rotary microwave drying. It is concluded that the kernel cracking ratio is lower when microwave drying of soybean was carried out in rotary state. Higher unit microwave power input results in rapid removal of water from soybean but an increase of kernel cracking ratio.

This paper presents an experimental study on the preparation of gram-negative bacteria microcapsules by spray drying. Effects of operating conditions on the bacteria survival rate were examined by single factor analysis. Through orthogonal experiment, appropriate conditions were determined as 160°C of the inlet air temperature, 12.5 ml/min of the feed flow rate, 1:9 of the ratio between gum arabic and maltodextrin, and 50 ml of fluid nutrient medium with the bacteria. The bacteria survival rate reaches 84.57% associated with above conditions. Examination of storage performance shows that after preserving in plastic film bag for 6 months under ambient temperature from 18°C to 30°C, quantity of the viable gram-negative bacteria was increased by 148%, which was significantly improved compared to those inoculated from laboratory.

There is a large demand for redispersible emulsion powder in various industrial applications because of its unique features. However, the use of this novel material is hindered by the complex synthesis processing technology and consequently high cost. In this paper, a simple preparation method for building material used redispersable emulsion powder is proposed. This method mainly includes two steps, a core-shell emulsion polymerization reaction and a following spray drying. In the emulsion polymerization step, AVE and MMA were used as seed emulsion and shell monomer for the core-shell polymeric structure. The influences of various factors such as monomer ratio, emulsifier and initiator as well as the feed method on particle configuration of core-shell structure polymeric emulsion were investigated. The suitable conditions to prepare the emulsion powder are: SDS as the emulsifier, KPS as the initiator, 40°C of the reaction temperature, and 2:1 of the ratio of the core to shell with a semi-continuous process. The successful fabrication of core-shell bedded structure was verified with scanning electron microscope. In the following spray drying step, the optimized operation parameters are: 150°C of the inlet air temperature, 75°C of the outlet temperature, and 10.5 ml/min of the feed flow rate. Under optimized operating conditions, coated milk white emulsion powders with uniform size, good fluidity, and good membrane performance were obtained.

This paper investigated experimentally the influences of gas flow type, position of heat source and gas flow rate on the properties of a heat exchanger with a Self-Excited Mode Oscillating-Flow Heat Pipe (SEMOFHP). The SEMOFHPs were made from copper with an inner diameter of 3mm. Distilled water was used as working liquid. The results showed that the heat exchange capability of the SEMOFHP heat exchanger is about 3 times higher than that of a common tube heat exchanger. The heat exchanger unit used in the experiments was operated under counterflow, bottom heat source and high gas flow rate conditions. However, it was found that the unit could also work well with a top heat source arrangement. The heat recovery efficiency of the heat exchanger is slightly increased with the increase of inlet air temperature. The SEMOFHP heat pipe works only when the hot gas temperature is higher than the initial temperature.

Toona sinensis, whose young leaves and shoots are edible and nutritious, is a perennial deciduous tree vegetable. In this paper, the volatile constituents of dehydrated fresh young leaves of Toona sinensis obtained by different drying methods were micro-extracted in solid-phase, and then analyzed with gas chromatography-mass spectrometry (GC-MS). The major flavor components include caryophyllene, aromadendrene, nonadecane, and phytol. Comparing with convection oven drying and natural solar drying, vacuum drying and microwave drying can preserve most of the original flavors of Toona sinensis.

Milling, an important processing step of rough rice, is usually done to produce white, polished grains. In this paper the quality of 22 milled rice varieties, common in Mazandaran, Iran, are investigated. These rice varieties included local varieties and breeding lines. Parameters assessed were head rice yield, degree of milling, husk removed percent, and total milling recovery. Results obtained revealed that the Tarom Mahali and Champa varieties have the highest head rice yield as 60.58 and 66.39 % and total milling recovery as 69.96 and 71.38 %, respectively. The greatest degree of milling value was found for the Haraz variety with a mean of 16.06 %. Also, it was found that the husk removed percent values were not statistically different among the varieties studied. Finally, considering all results obtained, the varieties of Tarom Mahali, Champa, and Neda showed to be more economical in the milling process.

Mesoporous alumina was prepared by using sucrose as a structure-directing template in an aqueous system. The resultant samples were characterized by using different methods such as x-ray diffraction, transmission electron microscopy, nitrogen adsorption-desorption analysis, and thermogravimetric and differential thermal analyses. The results showed that the prepared mesoporous gamma alumina has high surface area, uniform pore size distribution and excellent thermal stability.

The chemical composition and the physical and sensory characteristics of three types of Majorcan cheese (half-ripened, ripened and old-ripened) were studied. In total, 22 parameters (7 chemical, 7 physical and 8 sensory) were evaluated using ANOVA and Tukey's multiple range test. Only 15 variables exhibited significant changes (p<0.001) during ripening. Principal component analysis (PCA), cluster analysis of variables (CAV) and stepwise discriminant analysis (SDA) were applied to estimate the usefulness of the chemical, physical and sensory determinations for the differentiation and classification of Majorcan cheeses. PCA allowed the reduction of 15 variables to 3 independent components accounting for the 85.6% of the explained variation. The first principal component was representative of the ripening stage. CAV confirmed the correlation between the studied variables obtained by PCA. Using SDA it was determined which variables best classified the cheese samples according to their ripening stage. Finally, the classification functions allowed the correct classification of 93.5% of the cheese samples.

The paper presents an artificial neural network based approach to corroborate the effect of variations in illumination, distance of image acquisition and size on recognition and classification accuracies of bulk food grain image samples. Different food grains samples like Wheat, Groundnut, Green gram and Jowar are considered. The image samples are taken by varying acquisition distances, illumination and sizes. The natural light source and the minimum distance of 40 centimeters are ideal for image acquisition compared to other light sources and varying distance of image acquisition. The experimental results have shown a reduction in accuracy in all the cases other than natural lighting condition and fixed distance of acquisition. The same is true with human vision system too. Variations in image sizes also affect the recognition and classification accuracies. Hence, it is inferred that any variation in the size of the image and the distance of acquisition has an impact on the accuracy of recognition of food grain samples.

Changes in the quality of sweet potato during hot air drying, such as L-ascorbic acid, sugar content, surface color and hardness, and drying characteristics, were investigated at temperatures of 30, 40, 50, and 60°C. Equilibrium moisture contents (EMC) of sweet potato samples in the desorption process were measured by a static method at the four aforementioned temperatures and six selected relative humidity levels. Using both the measured moisture content data in the drying test and the EMC values, hot air drying characteristics of sweet potato was estimated. Changes in L-ascorbic acid content of sweet potato during hot air drying was measured, wherein a first-order reaction rate equation was applied to model the change in decomposition of L-ascorbic acid content. In addition, surface color, sugar content, and surface hardness were also measured. The total color change (?E) of the samples was observed to decrease as drying temperature was increased. The effects of sample sugar concentration on surface hardening during hot air drying of sweet potato are discussed.

The purpose of this study is to establish optimum extraction temperature, moisture content, particle size and the effect of roasting of shea kernels on extraction efficiency for optimum shea butter yield using low pressure (45kg/cm2) manual screw press. Extraction of shea butter is a major income generating activity in Ghana, particularly in the Northern Regions. It is estimated that about 80% of the shea butter produced in Ghana is processed by women using traditional aqueous extraction method. Commercial extraction using continuous screw press accounts for about 20% of production. Oil extraction rates for the traditional aqueous extraction method are relatively low. The traditional aqueous method involves roasting, milling, creaming and boiling, and relies on very low pressure, high moisture of 65-68% and temperatures of 100-140°C. In this study Intermediate Moisture Content (IMC) method was employed. The IMC method involves the use of a low pressure manual screw press to extract butter from shea kernels. The study established an optimum extraction temperature of 60°C and moisture content of 12% at which butter extraction efficiency was between 65.9% and 68.5%. The results revealed that oil extraction efficiency depends on the fineness of paste to be processed and that roasted kernels do not give higher butter yield than unroasted kernels. This is against the traditional belief that high shea butter yield can only be achieved when the kernels are roasted.

In this study, a heat pump dryer with heat recovery (HPHR) was employed to dry the paddy with high moisture content. The paddy (w. b.) was about 30% initial moisture content and 1200kg in each batch. After drying process, the final moisture content was 14%, and the average energy consumption of HPHR was 10.5kw•h/100kg (based on the weight of final paddy). The total drying time, drying cost and energy consumption were 88%, 64% and 58% of those using diesel-powered low-temperature heated air drying.

The effect of the drying rates of fruit and cladode of Opuntia Ficus Indica was examined at different temperatures. The experimental drying curves show only a falling drying rate period. The values of drying rate of prickly pear (fruit and cladode) almost doubled when the drying temperature was increased from 40 to 60°C. The experimental drying data were applied to various drying equation (Logarithmic; Wang and Singh, Henderson and Pabis, MMF model and Midilli equation). Midilli equation was optimal for characterizing drying behaviour of prickly pear for the whole range of temperature with a correlation coefficient of 99.99% for the fruit and the cladode and a standard error of 0.0015 for the fruit and 0.0017 for the cladode.

Processing cassava to gari is a storage method. Gari frying is the last operation and is still largely done manually in Nigeria. The women processors usually adopt various postures during production as appeared comfortable to them. This paper reports the survey carried out in 50 gari factories across five states (Ekiti, Ondo, Ogun, Osun and Oyo) of southwestern Nigeria and the versions of Improved Traditional Garification Methods (ITGMs) in use. These were grouped into eight (ITGM I-VIII) based on operator's and workplace's characteristics, heating process and estimated output. Their modes of operation were explained and estimation of their outputs and common working postures were determined. Four working postures were identified namely, sitting beside (SB), sitting in front (SF), alternating between sitting and standing (ASS) and standing (S). ITGM VIII with operator in standing posture using both hands had the highest output, having efficient use of both hands and indicating an ergonomic balance of right and left arms as well as overcoming certain asymmetric symptoms in the workers. ITGM VIII is, therefore, recommended based on output.