نشریه مهندسی بیوسیستم ایران
سال چهل و چهارم شماره 2 (پاییز و زمستان 1392)

Therefore، the objective of this study is to test the feasibility of UV-IR transmission spectroscopy for the non-destructive assessment of the freshness of an individual egg as an alternative for traditional inspection methods. To obtain a considerable variation in freshness، groups consisting of 10 eggs were stored (30 7 oC and 25% 4 RH) for 30 days. Data obtained from non-destructive spectral measurements were compared with three destructive freshness parameters including Haugh units (HU)، albumen and yolk pH as well as yolk coefficient (YC(. Partial least squares regression (PLSR) and principal component regression (PCR) models are built in order to predict HU، pH and YC based on the transmission spectra. The correlation coefficients between the predicted value and the measured value are 0. 88، 0. 86 and 0. 78 for HU، YC and pH of the albumen، respectively، in the PLSR method and 0. 64، 0. 62 and 0. 41 for HU، YC and pH of the albumen، respectively، in the PCR method. These results show that the light transmission spectrum of an egg provides better quantitative information about egg freshness based on PLSR method. Effective information concerning egg freshness is restricted to the wavelength interval between 510 and 820 nm.

In this research a flat plate solar air collector was investigated under direct solar radiation consisted of a slatted glass cover، perforated absorber aluminum sheets (porosity 0. 0177، 0. 0314 and absorber thickness of 2. 5 mm). The effect of porosity on absorber efficiency of collector was evaluated. Six levels of air mass flow rates (0. 0056 to 0. 0385 kg m-2 s-1) were adopted. Average solar energy was reported to be 1040 Wm-2. The experimental results show that thermal efficiency of collector increases by an increase in the porosity of the absorber. This improvement may be due to an increase in heat transfer surface area within the porous medium at higher air mass flux which yields a higher heat transfer coefficient. The absorber with lower porosity shows a better thermal efficiency at lower air mass flux because the air flows in the shorter path through the outlet air channel and may not able to cool the absorber effectively. In the minimum air flow rate، absorber efficiency with porosity 0. 0177 & 0. 0314 are 0. 31 & 0. 29 respectively whereas، at the maximum flow، efficiency shows an enormous change of 0. 83 and 0. 88 respectively. This solar air heater can be used for drying agricultural products، and etc.

Dehaulling is one of the important stages in sesame grain processing. It includes soaking، dehusking the grain، and separating the husks from kernels. In the present study، a continuous dehuller for an industrial continuous process layout of grain was designed، fabricated and evaluated. The slope and speed of dehuller were the main factors for laboratory experiments. Results depicted both factors have significant effect on dehulling efficiency (p=0. 01). Maximum efficiency was measured about 84 percent at zero slope and minimum speed of dehuller in a single pass trial. A strong linear relationship between dehulling duration time and efficiency with correlation coefficient of 0. 80 was observed. This machine has capability of extra efficiency with increasing in dehulling duration through other adjustments.

Using image processing and artificial intelligence systems in agriculture and food industry is increasing daily. The purpose of this research is to study the feasibility of using image processing technique in predicting process of moisture content changes on green tea sheets during the drying using predictive artificial intelligence systems such as: artificial neural networks and adaptive neuro-fuzzy inference system. The drying experiments were conducted at five temperatures of 50، 60، 70، 80 and 90 °C and three air flow rates of 0. 5، 1 and 1. 5 m/s using thin layer method. The results gained out of extracting colorful images took from upper view of samples were applied as input data of artificial intelligence systems for determining moisture content. Finally، the best results predicted by the artificial neural network with two hidden layers contained (12 neurons in the first layer and 15 neurons on the second layer) with correlation coefficient of 0. 948 and root mean square error of 0. 092، respectively.

In this study، the morphological and chemical properties of carob pods and carob beans as well as the effect of different extraction، and purification methods on the physical and chemical properties of the purified gums have been investigated. In order to dehusk carob beans، boiling water as well as acidic methods were used. The endosperm powder was prepared and the effect of endosperm powder concentration (1– 3%)، pH (4، 7، and 10) and heat treatment (50– 90°C) on the extraction of the crude gum were evaluated based on an RSM design. The resulting dispersion was centrifuged and the supernatant recovered. Purification of the gum was followed by adding alcohols and acetone into the supernatant. Results of dehulling treatment showed that the endosperms which treated by sulfuric acid (twice) were more transparent than others. Moreover، the solubility of the gum was increased by rising the temperature.

Regarding outbreak of coeliac in some parts of the world، production of free-gluten cakes is increasing worldwide. Rices is often advised for people suffering from coeliac. In this research، the effect of adding xanthan and carboxy methyl celloulose gums on qualitative، sensory and staling properties of rice cakes was studied. The said gums were added at two concentrations of 0. 25% and 0. 75% and the effects of different concentrations were evaluated on different properties of rice cakes. Results obtained from chemical tests showed that moisture، ash and protein content of samples containing xanthan and carboxy methyl celloulose gums was increased compared with control sample. Also adding of the said gums at two concentrations mention resulted in an improvement of sensory and staling properties compared with control samples.