Journal of Agricultural Science and Technology
Volume:10 Issue: 3, Jul 2008

Proteins are not only considered as a nutritional source but also are responsible for a number of functional properties such as solubility, emulsification, foaming capacity and gel formation in food products. However, insolubility of the proteins (as can be seen in gluten) and therefore their insufficient functional properties have created some limitations for their incorporation in formulated foods. Studies have indicated that chemical and/or enzymatic modifications are potential ways to improve proteins functionality. In this study gluten was extracted from two wheat varieties, Sardary and Mahdavi, and then modified by deamidation, acylation (succuinylation and acetylation) as well as enzymatic hydrolysis. Functional properties such as solubility measured as nitrogen solubility (NSI), emulsifying capacity (EC), foaming capacity (FC) and stability (FS) as well as the electrophoresis patterns of native glutens were studied and compared with those of chemically- and/or enzymatically-treated samples. Most modifications significantly increased NSI from 20 to more than 70% and EC up to 35%. A great increase was also evidenced in foaming capacity that increased from 80 ml of foam volume in native samples to about 180 ml of foam in all the treated samples; however, only deamidated samples had stable foam over the time. Electrophoresis patterns indicated that, among chemical modifications, deamidation caused limited hydrolysis of gluten polypeptides while enzymatic hydrolysis led to a pronounced reduction in the molecular weight of wheat gluten polypeptides (less than 15 KD) of both varieties.

Proteins are not only considered as a nutritional source but also are responsible for a number of functional properties such as solubility, emulsification, foaming capacity and gel formation in food products. However, insolubility of the proteins (as can be seen in gluten) and therefore their insufficient functional properties have created some limitations for their incorporation in formulated foods. Studies have indicated that chemical and/or enzymatic modifications are potential ways to improve proteins functionality. In this study gluten was extracted from two wheat varieties, Sardary and Mahdavi, and then modified by deamidation, acylation (succuinylation and acetylation) as well as enzymatic hydrolysis. Functional properties such as solubility measured as nitrogen solubility (NSI), emulsifying capacity (EC), foaming capacity (FC) and stability (FS) as well as the electrophoresis patterns of native glutens were studied and compared with those of chemically- and/or enzymatically-treated samples. Most modifications significantly increased NSI from 20 to more than 70% and EC up to 35%. A great increase was also evidenced in foaming capacity that increased from 80 ml of foam volume in native samples to about 180 ml of foam in all the treated samples; however, only deamidated samples had stable foam over the time. Electrophoresis patterns indicated that, among chemical modifications, deamidation caused limited hydrolysis of gluten polypeptides while enzymatic hydrolysis led to a pronounced reduction in the molecular weight of wheat gluten polypeptides (less than 15 KD) of both varieties.

Heat stress is a major environmental stress limiting wheat productivity in most cereal growing areas of the world. In order to map and characterize quantitative trait loci controlling heat tolerance, 144 recombinant inbred lines deriving from the cross of Kauz and MTRWA116 were assessed in a greenhouse and growth chamber at 35˚C. One hundred and sixty six SSR and 3 AFLP markers were used to construct a linkage map containing 18 linkage groups and covering 16 chromosomes of wheat. Using the composite interval mapping method, three QTLs were detected for heat tolerance and measured by the Fischer susceptibility index, on chromosomes 1B, 5B and 7B. The alleles of both parents contributed to heat tolerance. A large amount of explained phenotypic variances and small confidence intervals indicate that the linkage information between markers and QTLs could easily be used in breeding for heat tolerance.

Conjunctive use of ground and surface water can increase reliability of the water supply by providing independent sources. In this study, corrected utility-efficient programming that allows for more than one seasonal irrigation depth for each crop was used to determine the amount of utility maximizing investment in the well capacity for conjunctive use. Results showed that optimum investment at the 15% discount rate for the small, medium and large representative farms with a low degree of risk aversion is 150341, 531592.7 and 1084648 thousand Rials, respectively, which decreases as aversion to risk increases.

Discovering the effective factors in agricultural students’ academic success was the aim of this study. The statistical population consisted of all 194 junior agriculture students at the University of Tehran. The study is of a correlation type with the information being gathered through questionnaires as well as through a study of students’ academic files. There was a positive significant correlation observed (P= 0.01) between academic success, on the one hand, and high school grade point average (GPA), study hours, planning for study, motivation, and emotional atmosphere of educational environment, on the other hand. The level of confidence between academic success, on one hand, and the family’s attitude towards studies and years of experience in teaching, on the other, being also significant (p= 0.05). Female students were found to be more successful than males. There was no significant difference observed between the academic success of students in residences and those who lived with their parents. Students with agronomy majors were shown to have a higher academic success as compared to students majoring in other eleven majors within the agricultural faculty. The results of regression analysis also demonstrated that 63.5 percent of the variations in the dependent variable academic success were expressed through high school grade point average (GPA), motivation, method of learning, father’s level of education, and the emotional atmosphere of the educational environment.

The purpose of this study was to determ the degree, level and capacity indices of agricultural mechanization in Sarab Region (N: 37º45'', E: 47º30'') in Eastern Azarbayjan Province, comprising about 65,164 hectares of farming land. The number of tractors, types of machines, and degree, level, and capacity of mechanization were calculated as the method of study. Data showed that the average level of mechanization was equal to 0.83 (hp per ha); partial energy expenditure per hectare (mechanization capacity) by energy producing sources (human, animal and machine), was 1.24%, 2.23%, and 96.35 % respectively. The results show the importance of the role of the machine in production. Although the level of mechanization in this region was higher than the national mechanization level, the degree of mechanization was very low in most of the farming operations. It was estimated that to reach the mechanization level of 1.5 hp ha-1, 775 tractors are required. In this study some overall guidelines for improving mechanization and increasing farm production are also presented.

Biofuels are the main substitute to fossil fuels. These fuels are less polluting in comparison to fossil fuels and can be produced from agricultural material residues for use in diesel engines. In this research work bioethanol was produced from potato waste. It was dehydrated in a vapor phase using 3A zeolite and was used in combination with sunflower methyl ester oil and diesel fuel blending which was evaluated thereafter. The sunflower methyl ester was also produced using a transesterification method. Considering the laboratory conditions and fuel stability limits to be used, the suitable blending proportion of bioethanol and diesel fuel was determined to be 12 to 88 and then, for maintaining fuel stability at temperatures lower than 15oC, the sunflower methyl ester was added to the mixture. The pour point of the fuel and different fuel blends, the viscosity, cetane number, flash point, amount of fuel ash, sulfur content and copper corrosion were determined in the laboratory. Experiments show that ethanol plays an important role on the flash point of the blends. With the addition of 3% bioethanol to diesel and sunflower methyl ester, the flash point was reduced to 16oC. The viscosity of the blends was reduced with the increase in the amount of ethanol. The sulfur content of bioethanol and sunflower methyl ester is very low compared with that of diesel fuel. The sulfur content of diesel is 500 ppm whereas that for ethanol and sunflower methyl ester is 0 and 15 ppm, respectively. The lower amount of sulfur content facilitates the use of fuel blends in diesel engines. For the ethanol and sunflower methyl ester combination, this amount is less than 20 ppm.

The objective of this study was to examine the effects of the fluidized-bed drying method on the final quality of two varieties of Iranian rice, medium- and long grain. The results were compared to that of paddy drying using a traditional method. Rough rice was treated in the fluidized bed drier at 140ºC for 2 minutes. Similar samples were dried for 8-10 hrs by the traditional method. Dried samples were dehusked and polished. Quality factors, including trade quality (head rice yield percent and whiteness), cooking quality (amylose content, gelatinization temperature, gel consistency, aroma and flavor) and nutritional quality (thiamine and lysine contents), were then measured for each sample. Finally, the data was analyzed. Results show that paddy drying in a fluidized bed dryer would reduce the quality factors except for rice whiteness for which conventional drying is more acceptable. Therefore modification of fluidized-bed drying technique is recommended.

Acetylation is a chemical modification of wood to enhance its properties. IR-spectroscopy is a useful technique for proofing chemical bondings in wood and the Attenuated Total Reflection (ATR) Infrared Spectroscopy technique was applied as an easier technique over other IR-spectroscopies. In this research, different degrees of acetylation, weight percentage gains (WPGs) in beech and pine mini-stakes were achieved by using acetic anhydride. Acetylated samples were analyzed by applying an Attenuated Total Reflection (ATR) Infrared Spectroscopy technique. Comparison of the acetylated samples with non-acetylated woods showed that hydroxyl groups (O-H) were diminished at wave numbers of about 3,354-3,328 cm-1 due to the substitution of hydrophobic acetyl groups in cell wall polymers. A strong peak appeared at wave numbers of about 1,733-1,728 cm-1 in beech and 1,737-1,728 cm-1 in pine due to the carbonyl (C=O) stretching of acetyl groups. The magnitude of the bands increased with raising the weight percentage gains (WPGs). The methyl deformation of the acetyl groups induced at wave number 1369 cm-1 caused by the stretching of C-H in polysaccharides. There was also a clear increase in the magnitude of the wave numbers at about 1234-1226 cm-1 in beech and 1236-1226 cm-1 in pine due to the stretching of C-O and carbonyl deformation in the ester bonds during the acetylation of lignin.

Considerable information exists in the literature showing that expansive layer silicates are not the only clay minerals present in vertisols. However, the presence of a very high clay content dominated by fine clay, regardless of the clay type, together with the wetting and drying cycle in the soil can also produce a high shrink-swell potential. We studied some vertisols with diverse parent materials and climates from western Iran to investigate the role of parent material and climate on formation of these soils. The vertisols of Fars Province (Southwest Iran) have formed on calcareous sediments with ustic-hyperthermic soil moisture and temperature regimes and a mineralogical composition dominated by a palygorskite-chlorite suite. The vertisols of Lorestan Province (Midwest Iran) are also formed from calcareous sediments under the xeric moisture and thermic temperature regime, and contain vermiculite as the dominant clay mineral. In Kermanshah Province, vertisols have formed on limestone or in calcareous sediments. They have xeric-thermic soil moisture and temperature regimes. In Ardebil Province, vertisols are formed on volcanic sediments, and they have xeric-mesic soil moisture and temperature regimes. All vertisols, except those from Fars Province, are classical ones and include montmorillonite in the clay fraction. Our study shows that the interparticle pore size that is controlled by the size of primary particles, regardless of its nature, contributes to the shrink-swell potential in the soils we studied in Iran.

This paper describes a simple, physically-based conceptual model utilizing watershed drainage characteristics for rainfall-runoff simulation. This conceptual physiographic model is essentially based on the work of Najafi (2003), which has led to a model comprising the main tributary subwatersheds and a single main channel subwatershed. The Kinematic Wave (KW) theory is used to describe flow over the subwatershed plans. The dynamic wave theory is applied for channel flow computations to compute the watershed responses at the outlet. The proposed model was tested on a natural watershed where the results could be compared with the results obtained by Najafi (2003). The results show the proposed physiographic model has advantages over the former in terms of mathematical formulation and input data preparation as well as computation time requirements