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Processing Variables (processing + variable)
Selected AbstractsEffect of air flow rate on the foam fractionation of a mixture of egg white and egg yolkASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 2 2009Chris C. Stowers Abstract Foam fractionation was previously shown to be an effective tool for the separation of the two visible phases in a chicken egg: egg white and the egg yolk.1 This study is a continuation of the previous study with the objective of determining the optimal separation condition in terms of air flow rate. Our results show that air flow rate is a critical operational parameter when separating these protein-rich mixtures of egg white and egg yolk. The results show that respective concentrations of egg yolk and egg white phases change independently with respect to the air flow rate, leading to the observation that air flow rate could be exploited as a processing variable to selectively remove proteins from one section of the egg over the other section. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] The Frequency Accrual Speed Test (FAST): psychometric intelligence and personality correlatesEUROPEAN JOURNAL OF PERSONALITY, Issue 2 2001Ulrich Ettinger Performance on a putative psychophysical measure of information processing related to intelligence (Vickers' 1995 Frequency Accrual Speed Test, FAST) was assessed in relation to two psychometric measures of intelligence (Raven's Advanced Progressive Matrices and the Mill Hill vocabulary test). Participants (N,=,57) completed the Eysenck Personality Questionnaire , Revised (EPQ-R), and performed the FAST task under either low (70 dB) or high (90 dB) levels of white noise. FAST correlated with Raven's (r,=,0.56) and Mill Hill (r,=,0.28), as expected. FAST total scores were not affected by personality or personality-by-noise interactions. However, a measure of consistency of FAST performance (i.e. the standard deviation) was correlated negatively with total FAST scores (r,=,,0.37) and positively with (EPQ-R) extraversion (r,=,0.34). The results are discussed in terms of the validity of the FAST to explicate the information processing variables in psychometric intelligence. Copyright © 2001 John Wiley & Sons, Ltd. [source] Effect of processing variables on texture development in a mica-based glass,ceramicJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2003I. L. Denry Abstract The purpose of this study was primarily to determine the feasibility of heat-pressing a mica-based glass,ceramic with the use of commercially available dental equipment, and secondly to evaluate the effect of various processing variables on the degree of crystal alignment in the pressed glass,ceramic. The hypotheses were that the mica-based glass,ceramic could be successfully heat-pressed and that some degree of crystal orientation would be obtained, depending on the processing variables. The glass composition was melted at 1400 °C for 2 h and cast into 12 × 60-mm rods. Ingots (10 × 12 mm) were cut from the glass rods, heat treated, and heat-pressed under various conditions. The microstructure of the pressed specimens was investigated by SEM and compared to that of heat-treated controls. The length of Vickers-induced cracks was measured on heat-pressed specimens and heat-treated controls. The results showed that mica-based glass-ceramics could be successfully pressed with the use of commercially available dental equipment. The resulting degree of crystal alignment (texture) along the direction of pressing varied between 35 ± 6 and 79 ± 6. There was a linear relationship between the degree of texture and the apparent aspect ratio of the mica platelets. A significant decrease in the length of the Vickers-induced cracks in the direction perpendicular to pressing was observed, associated with an increase in length in the direction of pressing. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 64B: 70,77, 2002 [source] OPTIMIZATION OF PRE-FRY DRYING OF YAM SLICES USING RESPONSE SURFACE METHODOLOGYJOURNAL OF FOOD PROCESS ENGINEERING, Issue 4 2010OLAJIDE PHILIP SOBUKOLA ABSTRACT The effect of convective hot-air drying pretreatment and frying time at a frying temperature of 170 ± 1C on moisture and oil contents, breaking force (crispness) and color parameters of yam chips was investigated. Response surface methodology technique was used to develop models for the responses as a result of variation in levels of drying temperature (60,80C), drying time (1,5°min) and frying time (2,6°min). Drying pretreatment had a significant effect on oil and moisture contents, breaking force and color parameters of yam chips, with water removal exhibiting a typical drying profile. Response surface regression analysis shows that responses were significantly (P < 0.05) correlated with drying temperature and time and frying time. The optimum pre-fry drying condition observed was a drying temperature of 70,75C for about 3,4 min while frying for 4,5 min. PRACTICAL APPLICATIONS Deep-fat frying is a very important cooking method and a lot of effort has been devoted to manufacturing fried products with lower oil content and acceptable quality parameters. The information provided in this work will be very useful in manufacturing fried yam chips of acceptable quality attributes through the combination of drying pretreatment conditions. The result is very useful in considering different processing variables and responses at the same time as compared with single factor experiment common in the literature. [source] IDENTIFICATION OF IMPORTANT PRODUCTION VARIABLES AFFECTING HARD PRETZEL QUALITYJOURNAL OF FOOD QUALITY, Issue 3 2005N. YAO ABSTRACT The objective of this study was to determine the importance of raw material and processing variables that influence pretzel quality by utilizing a screening experiment design. Eleven variables were selected based on preliminary experiments, and a two-level-11-factor (211) fractional factorial experimental design was used to screen the variables. Several responses were measured for dough before and after extrusion, for half-baked and fully baked pretzels. These responses are important indicators of consistency and quality during pretzel processing. Results indicated that flour protein content, the amount of water added to make dough and dough mixing time were important variables influencing dough behavior. Caustic concentration affected brightness of half-baked pretzels but did not influence the color of the final product. Baking time was the most important factor for both half-baked product and final product qualities. The hardness of fully baked pretzels was influenced by baking time, temperature in baking oven zone 1, drying time and drying temperature. The color of final products was significantly influenced by baking time, while both baking time and drying temperature affected the moisture content of the final product. A key observation was that none of the raw material or dough processing parameters, within the range tested, influenced final pretzel quality as defined by pretzel moisture content, hardness or color. [source] Pasteurization of Fruit Juices by Means of a Pulsed High Pressure ProcessJOURNAL OF FOOD SCIENCE, Issue 3 2010Giorgio Donsì ABSTRACT:, The use of pulsed high hydrostatic pressure was investigated as a possible approach to stabilize foodstuffs. The objective of this article was to investigate the effect of the main processing variables (pressure [150 to 300 MPa], temperature levels [25 to 50 °C], and pulse number [1 to 10]) on the sanitation of nonpasteurized clear Annurca apple juice as well as freshly-squeezed clear orange juice. The aim of the article was the optimization of the process parameters in step-wise pressure treatment (pressure holding time of each pulse: 60 s, compression rate: 10.5 MPa/s, decompression time: 2 to 5s). The shelf life of the samples, processed at optimized conditions, was evaluated in terms of microbiological stability and quality retention. According to our experimental results, the efficiency of pulsed high pressure processes depends on the combination of pulse holding time and number of pulses. The pulsed high pressure cycles have no additive or synergetic effect on microbial count. The efficacy of the single pulses decreases with the increase of the pulse number and pressure level. Therefore the first pulse cycle is more effective than the following ones. By coupling moderate heating to high pressure, the lethality of the process increases but thermal degradation of the products can be detected. The optimization of the process condition thus results in a compromise between the reduction of the pressure value, due to the synergetic temperature action, and the achievement of quality of the final production. The juices processed under optimal processing conditions show a minimum shelf life of 21 d at a storage temperature of 4 °C. [source] Freeze-drying of tert- butanol/water cosolvent systems: A case report on formation of a friable freeze-dried powder of tobramycin sulfateJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 4 2002Sakchai Wittaya-Areekul Abstract A case study is presented in which a tert -butanol (TBA)/water cosolvent system was found to be a useful means of producing freeze-dried tobramycin sulfate that readily forms a loose powder upon agitation in a specialized application in which a critical quality attribute is the ability to pour the sterile powder from the vial. Both formulation and processing variables are important in achieving acceptable physical properties of the cake as well as minimizing residual TBA levels. Liquid/liquid phase separation was observed above critical concentrations of both drug and TBA, resulting in a two-layered lyophilized cake with unacceptable appearance, physical properties, and residual TBA levels. However, the choice of tobramycin sulfate and TBA concentrations in the single-phase region of the phase diagram resulted in a lyophilized solid that can readily be poured from vials. Crystallization of TBA before drying is critical to achieving adequately low residual TBA levels, and this is reflected in the effect of thermal history of freezing on residual TBA levels, where rapid freezing results in incomplete crystallization of TBA and relatively high levels of residual solvent. Annealing at a temperature above T,g of the system after an initial freezing step significantly reduces the level of residual TBA. Secondary drying, even at increased temperature and for extended times, is not an effective method of reducing residual TBA levels. © 2002 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 91: 1147,1155, 2002 [source] GELLING BEHAVIOR OF RICE FLOUR DISPERSIONS AT DIFFERENT CONCENTRATIONS OF SOLIDS AND TIME OF HEATINGJOURNAL OF TEXTURE STUDIES, Issue 3 2008ALKA KAPRI ABSTRACT Rice flour dispersions, under suitable conditions of processing, can form a gel. The effect of concentration of solids (10,18%) and time (0,75 min) of processing on textural attributes, and viscoelasticity were investigated along with sensory attributes. The textural attribute determined is gel strength, while viscoelasticity was determined in terms of mechanical spectra like storage modulus (G,), loss modulus (G,), complex viscosity (,*) and loss factor (tan ,) during a frequency sweep varying from 0.01 to 40 Hz at a constant stress of 25 Pa. Microstructural observation indicates the swelling of starch granules in the beginning of heating, while damaged granule and leached-out materials are visible at the end of the gelling process. Desirability function analysis has been applied to obtain a rice gel with acceptable textural attributes; a solid concentration of 15.2% and a heating time of 75 min can lead to the development of a gel with a satisfaction level of 0.6. PRACTICAL APPLICATIONS Rice flour gels in the form of hard-set gels, porridges and spreads are popular in several parts of the world particularly for feeding of infants and children. The application of the present study lies in understanding the role of major processing variables on the quality attributes and viscoelasticity of a product, characterization of cooked gels and for developing rice flour-based food gels. The findings may also be extended for the development of other cereal-based gels. [source] Effect of Microstructure on the Thermal Conductivity of Hot-Pressed Silicon Nitride MaterialsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 1 2002Angel De Pablos Si3N4 materials with distinct microstructures were prepared by hot-pressing, varying the holding time at the maximum temperature, and using different types and amounts of sintering additives. Materials with thermal conductivities of 15,82 W·(m·K),1 were obtained by changing the processing variables. The highest conductivity was measured for the material with the coarsest microstructure. The effect of microstructural parameters, such as percentage of secondary phases, grain size, and texture on thermal properties of Si3N4 ceramics, were studied. Hot-pressed Si3N4 ceramics were modeled as a two-phase composite made of large grains of high conductivity and a small-grained phase of low conductivity. [source] Enhanced strength of portland cement products via reinforcing polypropylene/fiberglass structures obtained from a novel processing techniquePOLYMER COMPOSITES, Issue 5 2003Yuanheng Zhang An uninterrupted filament winding process was used to fabricate structures made of polypropylene and glass fiber that provide superior reinforcement to Portland cement structures. Fabricated polypropylene/fiberglass composite tubes were filled with a cement mixture and some were reinforced with internal tapes. Three-point bending experiments, microscopic observation, and image analysis were used as tools to study various processing variables and their effect on the mechanical properties of the tubes. The temperature of the mandrel and wetting strongly affected the composite's mechanical properties. Increased temperatures diminished the void content within the composite and produced a unique "fuzzy" inner surface for the cylindrical tube. The development of this "fuzzy" inner surface improved the strength and fatigue properties of the cement filled composite tube by providing efficient load transfer to the glass fibres. Also the surface to volume ratio of the steel rebar geometry when compared to that of the polypropylene/fibreglass structure explains the superior load transfer to the glass. It was found that a tube reinforced with 15 internal tapes filled with a cement mixture recorded a maximum tensile stress of 71 MPa (10,000 psi) with excellent damage tolerance, more than a 10-fold increase over the upper bound value for steel reinforced cement obtained from the rule of mixtures. The tube continued to be load bearing to strains of 0.4, which is more than 40 times the failure strain of glass. These large failure strains are the result of the shear yielding of polypropylene that coats the glass fibres and allows them to move within the cement. [source] The occurrence of surface roughness in gas assist injection molded nylon compositesPOLYMER COMPOSITES, Issue 2 2000Shih-Jung Liu Gas assist injection molding has increasingly become an important industrial process because of its tremendous flexibility in the design and manufacture of plastic parts. However, there are some unsolved problems that limit the overall success of this technique. The purpose of this report was to study the surface roughness phenomenon occurring in gas assist injection molded thermoplastic composities. The materials used were 15 % and 35% glass-fiber filled nylon-6 composites. Experiments were carried out on an 80-ton injection molding machine equipped with a high-pressure nitrogen-gas injection unit. Two "float-shape" axisymmetric cavities were used. After molding, the surface quality of molded parts was measured by a roughness meter. Various processing variables were studied in terms of their influence on formation of surface roughness: melt temperature, mold temperature, melt filling speed, short-shot size, gas pressure, and gas injection delay time. Scanning electronic microscopy was also employed to characterize the composites. It was found that the surface roughness results mainly from the exposure of glass fiber in the matrix. The jetting and irregular flows of the polymer melt during the filling process might be factors causing the fiber exposure. [source] Effect of processing variables on the linear viscoelastic properties of SBS-oil blendsPOLYMER ENGINEERING & SCIENCE, Issue 12 2001F. J. Navarro Block copolymers, especially styrene-butadiene-styrene three-block copolymers (SBS), are recognized as especially effective asphalt modifiers because of their thermoplastic elastomeric properties. The concentration of copolymer, its ability to swell by the maltenic oils, and the processing variables are essential in the development of a three-dimensional network in the polymer-rich phase that enhances the vis-coelastic properties of these modified binders. This swollen polymer phase may influence the mechanical properties of the modified bitumens and synthetic binders. This paper deals with the influences that processing variables exert on the linear viscoelastic properties of oil/SBS mixtures in a wide range of temperatures. From the experimental results obtained we may conclude that most of the oil/SBS blends studied are highly structured thermoplastic gels above a critical SBS concentration that depends upon temperature, time of processing and surrounding atmosphere. [source] Processing of short-fiber reinforced polypropylene.POLYMER ENGINEERING & SCIENCE, Issue 1 2000An experimental investigation of the processing of glass fiber reinforced polypropylene is presented. Final fiber orientation distribution, fiber distribution in filament sections, rheological properties, final fiber length distribution and surface morphology were analyzed. This analysis was done taking into account the quantity of fibers and their interactions and flow conditions. The final fiber orientation increased when shear rate increased and fiber concentration decreased. Moreover, inhomogeneities in fiber distribution increased as the concentration of fibers decreased. The density profile showed a significant variation with fiber concentration, but it was not dependent on the shear rate applied. The viscosity showed a linear dependence with shear rate. The average fiber length and the breadth of this distribution decreased with the increasing fiber concentration and extrusion rate. The extruded filament surface showed minor roughness when the shear rate increased or when the fiber concentration decreased. The results of this experimental characterization give useful information to determine the influence of the processing variables on the final properties of short-fiber reinforced polypropylene and constitutes the first part of a more ambitious project that also includes the development of a modeling strategy of the processing behavior for short-fiber composites. [source] | |||||||||||||