Introduction: Kojic acid with the chemical structure of 5-hydroxy-2-hydroxymethyl-ˠ-Piron is an organic acid that is biologically produced through aerobic fermentation process by using various substrates and via the function of variety of fungi. This study was aimed to study the optimization of Kojic acid production by Locally Isolated Fungi Aspergillus sp., using ‘Response Surface Methodology’.Materials and Methods: Kojic acid was produced by fermentation of isolated strain of genus Aspergillus in submerged culture medium. Initial investigation in Kojic acid production process was performed via Plackett-Burman method and by using different nitrogen sources such as yeast extract, peptone, ammonium sulfate, ammonium chloride, urea as well as different carbon sources, including fructose, sucrose, glucose, lactose and maltose.Results: Based on our study, peptone and glucose were the most effective factors with carbon and nitrogen sources in production of kojic acid (P<0.05). The next step was production of 34.4g/L kojic acid by optimizing the effect of environmental factors such as temperature, pH, glucose and peptones, such as carbon and nitrogen sources, used in production of kojic acid and by employing ‘Response Surface Methodology’.Conclusion: Based on the results of this study, the maximum production of kojic acid can be achieved by using; glucose (%8.71), peptone (37.4%), temperature (29.9oC) and adjusting pH to 6.75 in the production process.

In this research, in order to separate germanium from an aqueous solution containing tartaric acid, liquid-liquid extraction (LLX) and supported liquid membrane (SLM) were employed. In these systems, polytetrafluoroethylene (PTFE) as the membrane and Alamine 336 as the carrier/extractant were used. In the LLX system, the effect of concentrations of extractant, tartaric acid, and HCl as a strippant was studied. As a result, the germanium extraction efficiency increased 100% after reaching Alamine 336 concentration to 10 %v/v. At the tartaric acid concentration of 0. 275 mM, the highest germanium extraction (98. 6%) was obtained. According to the SLM experiments, the carrier concentration of 15 %v/v was enough for the efficient transport of germanium from feed to strip phase. In comparison with LLX system, despite transportation of all germanium species in the SLM system, the time of this process (20 h) is higher than that of the LLX system.

A central composite face-centered design was used to study and to optimize lead biosorption from aqueous solution on Aspergillus terreus biomass. Four factors such as stirring speed, temperature, solution pH and biomass dose at different levels were studied. The hierarchical quadratic model were established by adding replicates at the central point and axial points to the initial full factorial design (24). The percentage removal of lead was affected by biomass dose, pH, and interactions between pH and biomass dose, pH and stirring speed, pH and temperature. The hierarchical quadratic model described adequately the Response Surface based on the adjusted determination coefficient (R2Adj=0.97) and the adequate precision ratio (42.21). According to this model, the optimal conditions to remove lead completely from aqueous solutions (at initial lead concentration of 50 mg/L and solutions of 100 mL) with Aspergillus terreus were at pH 5.2, 50oC, stirring speed of 102/min and a biomass dose of 139 mg. The Response Surface Methodology can be used to determine the optimal conditions for metal adsorption on several adsorbents. In addition, results reported in this research demonstrated the feasibility of employing A. terreus as biosorbent for lead removal.

Background and objectives: Rice is a very popular cereal in world and very important from economic point of viwe. The problems of drying paddy rice is lack of drying uniformity in the paddy rice that creates stress temperature and moisture and thus will cause losses in the later stages. The purpose of this research was to develop a high performance system for processing the paddy to healthy white rice in the shortest drying time. Materials and methods: In this study, to reduce losses and increase the drying rate, an innovative laboratory rotary dryer machine was used. The Response Surface Methodology (RSM) with central composite design was used for modeling and determinimg the optimum processing conditions for paddy drying. Independent variables for this process were temperature (40 to 80° C), cylinder rotation speed (2 to 10 rpm) and the cylinder fullness (25 to 66%). The percentage of breakage, percentage of crack and drying time were used as Response parameters to develop predictive models and optimize the drying process. Results: The results showed that the temperature, cylinder rotation speed and cylinder fullness had significant effect (P<0. 01) on the percentage of breakage, percentage of crack and drying time, as temperature was the most effective parameter. According to optimization process, the minimum losses (percentage of breakage and percentage of crack) and drying time were found with the inlet air temperature 56. 53 ° C, cylinder rotation speed of 10 rpm and the cylinder fullness of 54. 20%. Conclusion: Conditions and parameters of drying process had important rule in the final quality properties and losses of paddy rice. Our results revealed that RSM could be used to develop adequate prediction models for describing quality changes in paddy rice during drying. The changes in the quality parameters were adequately described by quadratic model. Also, the result showed that inlet temperature was more important than cylinder rotation speed and cylinder fullness on losses of paddy rice.

Since Amaranth (AM) is one of the dye compounds which is harmful to human’ s life its removal from industrial waste water would reduce their environmental impact and health effect. Copper nanoparticle (CuNP) is a simple and eco-friendly material which can be used to remove this pollutant. In this paper, copper nanoparticles were synthesized, for removal of AM dye. The experiments were designed by Response Surface Methodology with a modified cubic model to predict the variables. To investigate variables and interaction between them analysis of variance was used with high F-value (1. 44), low P-value (<0. 0409), non-significant lack of fit, the determination coefficient of 0. 898 and the adequate precision of 7. 25. Experimental and predicted values of the Response illustrated a good correlation. The optimum parameters catalyst amount (0. 14 w/w%), initial concentration (7. 38 mg/l), reaction time (47. 75 s) and pH (2. 83) for the highest removal percentage of (96. 10%) was attained.

Response Surface Methodology is used to optimize the parameters of a process when the function that describes it is not known and the experimenter wants to find the optimal solution of process input variables by RSM.In some cases, there is more than one Response and it is necessary to optimize them simultaneously. But the experimenter always knows about producer requirements (such as standards, objectives, etc.) and customer need can be another Response in multiResponse Surface problems. High technology industry, with more competitiveness, must continuously improve multiple correlated product quality characteristics and the consumer must assess them. This paper extends the ideas of a multiResponse Surface to the tracking of dynamic optimization, with respect to customer Response. Indeed, this study presents a new approach to formulate multiple Response customer voice (by using Conjoint Analysis) and other Responses and, also, by solving the correlated Responses using a metaheuristic optimization method. The proposed procedure is illustrated with an experiment from the literature.

Background: The presence of nitrate and its intermediates are considered undesirable compounds in the environment. Various methods have been proposed to remove nitrate from wastewater and water streams. Objectives: In this study, we investigated removal of nitrate from an aqueous solution by the process of electrocoagulation, using aluminum/graphite as the anode/cathode electrodes. Materials and Methods: We applied Response Surface Methodology (RSM) as the statistical method for modeling, and optimizing the applied variables. All experiments were performed according to the standard methods for the examination of water and wastewater. To prepare the optimum condition, we considered the following amount of compounds and conditions: NaCl, 1 g/L; nitrate concentration range, 50-200 mg/L; applied electric current range, 0.05-0.2 A; anode, aluminum; cathode, graphite; and detention time: 120 minutes.Results: The results showed that by applying electric current of 0.14 A for 120 minutes, the nitrate content would reduce down to 97%. The obtained R2 for the nitrate removal model was higher than 0.99. With regard to supporting electrolytes, more nitrate reduction is obtained with NaCl. The oxidation reduction potential (ORP) was changed from 220 to -375 mV and this range is suitable for denitrification and nitrate reduction. Conclusions: The results of this study show that it is possible to remove nitrate, and its intermediates from waste water. Regarding the desirability of the process, the field scale study is proposed.

Introduction: Compressing materials during the tableting process is an appropriate solution to increase the bulk density of agricultural materials and thus reduce their transportation and storage costs. Other benefits of using compact tablets include reducing environmental contamination due to the absence of fine particles and dust, increasing the nutritional value per unit volume due to compression, and also facilitating the control of compacted nutrients to meet nutritional needs (Kaliyan and Morey 2010). In order to improve the quality of the tablet, it is necessary to know the optimum conditions and working points of the device, as well as to find the relationships between the effective factors and the final product for the researchers, so optimizing the food processing processes is one of the most important. One of the most important steps in increasing the efficiency of the food industry. Numerous analytical and numerical methods are available for this purpose. Nowadays, statistical methods are used for optimization such as Response Surface Methodology (RSM). Response level Methodology is a set of statistical techniques used to optimize the processes in which the Response is affected by a number of variables. The graphical representation of the mathematical model has defined the word Surface methodically. With the help of this statistical design, the number of trials is reduced and all the coefficients of the quadratic regression model and the interactions of the factors can be estimated. In general, the models developed in Response Surface Methodology are generally quadratic (Lee et al., 2007). Increasing the speed of operation and increasing accuracy in achieving the desired goal are some of the criteria that are considered as an optimization method for quality evaluation (Asefi et al., 2015; Wani et al., 2017). Finding the best pelletizing conditions for agro-materials is of particular importance in order to achieve the highest quality pellets including the lowest wrinkles and the highest compressive strength. Therefore, it is necessary to find the optimum conditions for the variables of the tableting process such as moisture content, temperature of the feedstock, and mold size. Soy is used in the preparation of a variety of sauces, syrups, meat substitutes and ready-made foods (Dasilva et al., 2012). So far, no research has been done to optimize the pellet production from soy powder. The purpose of this study was to investigate the effects of independent variables of moisture content, die diameter, inlet temperature and stress relaxation time on the mechanical and physical properties of soybean powder and tablet formulations in order to determin the optimum conditions for achieving the highest density and compressive strength and the lowest amount of shrinkage of the tablet. Material and methods: In this research, soybean powder was used for tabletting experiments. Soybean dough prepared and used in a laboratory scale hydraulic press machine with a closed die to produce cylindrical tablets. When the hydraulic pressure reached 75 bar, the movement of the hydraulic jack was stopped, and the materials were kept in the closed die for the specified time (three levels of 5, 10 and 15 s) to reduce stress and prevent spring compression. At the end of the compressive relaxation process, the pressure of the jack was removed from the material and the tablet formed was removed from the bottom of the mold. The effect of the tabletting process on particle density, compressive strength and shrinkage of soybean tablet was studied. The experiments were carried out using soybean powder at feedstock moisture content of 30, 40 and 50% w. b., feedstock temperature 25, 45 and 60 ° C, relaxation time of 5, 10 and 15 s, and die diameter of 6, 8 and 10 mm. To measure the compressive strength of the tablets made from soybean powder, the Hounsfield Model K-S H50, was used for compressive strength testing. The test method was that a number of cylindrical compact tablets (in diameter) were positioned between the two fixed and removable flat jaws. The jaw was then moved downward at a constant velocity of 1 mm/s, compressing the cylindrical shape along the diameter until it was removed and fractured, and the amount of force and displacement in the memory of a data logger at a sampling rate of 1000 data points. Finally, the maximum recorded force for breaking the tablet was considered as compressive strength. To measure the particle density of the tablets, a number of tablets were inserted into the graduated cylinders containing a volume of 50 ml (readable to 0. 5 ml) of toluene. The volume of each cylinder was measured and recorded according to the volume changes of the cylinder. To measure product shrinkage, the height and diameter of a cylindrical compact tablet were measured in three different directions once before the drying process and once at the end of the drying process by a digital caliper. Then the average geometric diameter of the tablet was calculated from the related equation. The Response Surface method (RSM) with central composite design and six replications for central point was also used to analyze the data and optimize the process. Results and disscussion: The result showed that the highest particle density was 3714. 32 kg/mm 3 under conditions of the feedstock moisture content of 50% w. b., feedstock temperature of 25 ° C, relaxation time of 5 s, and the die diameter of 10 mm. During the tabletting prosses, the highest compressive strength (518. 18 N) was obtained at the feedstock moisture content of 50% w. b., feedstock temperature of 65 ° C, relaxation time of 5 s, and the die diameter of 6 mm. The highest shrinkage of soybean powder (57%) was obtained at the feedstock moisture content of 50% w. b., feedstock temperature of 65 ° C, relaxation time of 15 s, and the die diameter of 6 mm. The best optimization results for tabletting conditions for soybean powder was under feedstock moisture content of 50% w. b., feedstock temperature of 42. 03 ° C, relaxation time of 5 s and die diameter of 10 mm. The predicted values of particle density, compressive strength and shrinkage at the optimized conditions were 4895. 49 kg/mm 3, 433. 17 N and 9. 03% with a desirability of 0. 853, respectively. By increasing simultaneously, the temperature of the feedstock to the die from 30 to 45 ° C and decreasing the stress relaxation time from 15 to 5 s, the desirability index increased. Stress relaxation time had the most effect on this index. Conclusion: In this study, the effect of moisture content of raw materials, temperature of feedstock, die diameter and stress relaxation time on particle density, compressive strength and shrinkage of soybean tablets were studied. Also, the optimum conditions of the tableting process were determined by using the Response Surface method to obtain the best physical and mechanical properties. Under optimum conditions of the tableting process, a particle density of 4895. 49 kg / mm 3, compressive strength of 432. 31 N and shrinkage of 9. 03% were obtained. These compact soy tablets can be used in all cases where powdered or dried soy is used.

Film blowing is the most important method in producing polyethylene films. For years, low density polyethylene (LDPE) and linear low density polyethylene (LLDPE) blends have been used in blown film manufacture. In this paper basic mathematical models and Response Surface graphs have been used to illustrate the relationship between blown film fabrication variables and mechanical and optical properties of 50μm films made from LLDPE and LDPE blends. These films are currently used in various non-barrier packaging applications. Using a Box-Behnken statistical design experiment Methodology, the effects of LLDPE/LDPE ratios (25-75%), blow up ratio (1.5-2.5), melt temperature (215-235oC) and frost line height (1-3D) were evaluated on the mechanical properties, e.g., tensile and tear properties in both machine direction (MD) and transverse direction (TD) and impact strength as well as optical property such as haze. The R2 values of all the Responses of mathematical models are obtained to be more than 0.85 which is an indication of very good fitting of the model with the experimental data of Response Surface method used. Although this study is confined to the equipment and resin types used, it can offer some curves and equations for predicting the properties of produced films. The processors can use these data to find the first approximation of the most important blown film parameters to achieve their favorite product properties.