Feed Moisture Content Research Articles

Dynamics And Assessment of Some Control Strategies of a Simulated Industrial Rotary Dryer

ABSTRACT Rotary dryers are widely used for the continuous drying of minerals and chemicals on a large scale. Hot gases are passed parallel to the flowing solid to achieve the desired product moisture content. Because these dryers are energy intensive, it is mandatory to operate them as efficiently as possible to respond to economic pressures. Using a dynamic rotary dryer simulator for mineral concentrate, five control strategies are evaluated and compared. Two control strategies are based on PI controllers and the others use neural network models. Results clearly show that a feedforward action, in conjunction with a PI controller or incorporated within the structure of a neural network model, led to the best performances provided an accurate measurement of the feed moisture content is available.

SENSORY AND PHYSICAL PROPERTIES OF EXTRUDED POTATO PUFFS1

ABSTRACTAlthough extrusion is widely used for snack foods, there are few descriptive sensory analysis studies of extrudates. This study investigated the effects of potato granule type (flour or flakes), feed moisture content (16%, 18% and 20%) and addition of oil (0%, 2% and 4%) on sensory attributes of extrudates. Generalized Procrustes analysis (GPA) and Principal Component analysis (PCA) were used to describe the relationship among the sensory attributes. Additionally, GPA described the relationship between selected sensory and physical variables. Feed moisture content, as a primary factor, and added oil, as the secondary, affected the puff characteristics. High feed moisture puffs were high in hardness and chewiness, whereas low moisture ones were high in brownness, burnt flavor and fracturability. Added oil changed sensory expansion with relation to low feed moisture. Using GPA, physical properties related to appearance, color and texture were matched with corresponding sensory attributes.

Selected Properties of Extruded Potato and Chicken Meat

ABSTRACTChicken thigh meat (CTM), (0–40%) was mixed with instant mashed potato and twin‐screw extruded. Feed moisture content (FMC), (15 or 20%) and screw speed (SS) (250 or 300 rpm) were varied. CTM affected expansion, bulk density, mean cell size, plateau stress, fracturability and solubility. Protein, fat, free fatty acid and ash increased and carbohydrate decreased as CTM increased. Extrudates produced at low feed moisture (15%) had higher compressive resistance, fracturability and solubility. Extrudates produced at high feed moisture (20%) had higher bulk density and mean cell size. Screw speed had no influence except on expansion degree (p≥0.05). Increased CTM changed microstructure from rough, thread‐like sheets to a flat, agglomerated carbohydrate‐protein laminar phase. Panelists reported no differences in overall acceptability among 0% CTM extruded at 20% FMC, 20% CTM extruded at 15% FMC and 20% CTM extruded at 20% FMC.

APPLICABILITY of A SHEAR INDUCED RATE CONSTANT MODEL to CONVERSION of CORN MEAL IN A TWIN-SCREW EXTRUDER

Data obtained from extruding corn meal in a corotating twin-screw extruder was used to test an Arrhenius type shear induced rate constant model, ks= ks,o exp (—Es/), where ks was shear induced rate constant, Es was shear activation energy, was shear stress, and was molar volume. A rheological zone was created by placing a reverse screw 300 mm from the die where the temperature was at 60C, sufficiently low that thermal effect on conversion of the material into gel or melt could be neglected. Throughput was used as an independent variable to generate various levels of shear input, while screw speed and feed moisture content were kept constant. Conversion of the material in the rheological zone was determined using differential scanning calorimetry, and the rate contant ks was calculated assuming zero order kinetics. A plot of ks vs. 1/ followed a straight line, confirming the applicability of the model to twin-screw extrusion under the experimental conditions. the shear activation energy Es was 40 cal/mole, comparable to the literature values obtained from single screw extrusion and capillary rheometry.

Modelling the effects of peanut flour, feed moisture content, and extrusion temperature on physical properties of an extruded snack product

SummaryA mixture experimental design was used to evaluate the combined effects of non‐fermented (PDPF) and fermented (F‐PDPF) peanut flours, added feed moisture content, and extrusion temperature on physical properties of extruded cornstarch‐peanut flour‐based snacks. Moisture content, expansion ratio, bulk density, modified Kramer compression‐shear force and colour of extrudates were significantly affected by the amount of PDPF and F‐PDPF in the formulation. Oil absorption by extrudates was only influenced by the type of peanut flour. Within the range of (per 1‐kg batch) 0.30–0.34 g g−1 added water, 0.16–0.20 g g−1 PDPF and/or F‐PDPF, and extrusion temperatures of 125 to 150°C, extrudates with a wide range of functional characteristics can be produced.

Influence of extrusion variables on subsequent saccharification behaviour of sago starch

This study reports the effects of substrate concentrations (21.6–38.4 g/100ml), amyloglucosidase (AMG) concentrations (0.66-2.34 U/g) and hydrolysis time (14.8–65.2 h) on the saccharification of sago starch extrudates. Regression analysis established AMG concentration and hydrolysis time as the most significant factors; a generated regression equation adequately predicted the outcome of saccharification. Using 30 g/100 ml solid content, 65.2 h and 2.34 U/g of AMG, syrups of highest glucose content (87.9%) were attained. Effects of extrusion conditions, i.e. feed moisture content (21.6–38.4), enzyme (Termamyl 120L) concentrations (1.48–6.52%) and mass temperatures in the compression and die zones (70.5–97.5 .C) during the combined gelatinisation and liquefaction of sago starch, on the amount of glucose produced were evaluated. Enzyme concentrations and feed moisture contents had the most pronounced effects on saccharification, which ranged from 47.6 to 73.3% (DE = 85–94) and 54.5–93.8% (DE = 90–98) after 24 and 65 h, respectively. Response surface plots suggest that a higher percent saccharification can be achieved when sago starch is extruded at high Termamyl concentrations but low moisture contents.

The Effects of Extrusion Conditions on the Physical Properties of Wheat Flour Extrudates

AbstractThe effects of extrusion conditions (feed moisture content and rate, process temperature, screw speed and geometry, and die diameter) on expansion ratio, bulk density, and breaking strength of wheat flour extrudates were investigated. Extrudate samples were prepared by using a Brabender single‐screw extruder. Higher feed moisture content and process temperature were required for proper expansion. At 3.18mm die opening, the relationship between expansion and bulk density was positive. Feed rate was the most effective factor for increasing bulk density. Breaking strength was significantly decreased with increasing process temperature.Under extrusion conditions of 22% feed moisture, 110g/min feed rate, 160°C process temperature, and 130rpm screw speed with 5:1 CR, wheat flour was puffed with low bulk density and breaking strength.

Dynamic modelling for a twin screw food extruder: Analysis of the dynamic behaviour through process variables

Food extrusion processes are multiple input, multiple output complex systems. In this paper, the extrusion cooker is simplified into a single input, single output dynamic system, even though multi-input tests have also been performed. Its dynamic characteristics are obtained with step tests on different operating variables: feed rate, moisture content and screw speed. The response is monitored on the following outputs: melt pressure, melt temperature and specific mechanical energy. The results show the following: — the behaviour of the extruder generally verifies the conditions of the BIBO (Bounded Input, Bounded Output) stability, — the process can be considered to be stationary and non-linear. The non-linearity of the system is highlighted by: — the variability of the steady state grain as a function of step magnitude, — the lack of superimposition of the gains when performing multi-input tests. The study of the transient behaviour shows that the systems exhibit a non-separable non-linearity. The observed dynamic characteristics are rising problems that must be taken into account in designing control systems for food extrusion.

Effects of Dietary Protein Level on Carcass Composition of Broilers at 5 to 15 Days of Age.

Few reports have been available concerning the relationship between dietary protein level and body composition of broilers at starting stage (0-3 weeks of age) under the same metabolizable energy (ME) condition. Preceding determination of the amino acid requirement of broilers using body weight gain as a main criterion, the effects of dietary crude protein (CP) on the carcass composition of broilers were studied.To the experimental diets mainly consisting of corn, whole egg protein was added as a good protein source to contain 3, 200 kcal ME/kg and 6 levels of CP from 12.1 to 21.1% arithmetically. Five broilers for each diet were fed ad libitum the experimental diets from 5 to 15 days of age after nutritional effects of yolk sack decreased. On the 15th day, they were sacrificed after recording the body weight and feed consumption, and mois-ture, fat, protein and ash contents of the carcass were determined. The body weight gains reached the maximum level at 16.2% CP and the feed efficiency reached the maximum level at 15.0% CP. Percentage of the carcass moisture (Y1), protein (Y2) and ash (Y3) increased linearly and, to the contrary, that of fat (Y4) decreased linearly with increasing the dietary CP level as follows: Y1=0.284X+61.27(r2=0.658) Y2=0.236X+11.50(r2=0.606) Y3=0.266X-0.86(r2=0.939) Y4=-0.786X+28.09(r2=-0.935) where X is percentage of the dietary CP.The highest ratio of retained protein, to ingested one was 71.9% at 14.9% of the dietary CP level and that of retained energy to ingested one was 52.6% at 14.9% of the dietary CP level.The contents of the digestive tracts increased with increasing the dietary CP level and body size. However, they did not affect the estimation of the requirements.

Application of fuzzy logic and neural network technologies in cone crusher control

Fuzzy Logic presents a robust technique for accommodating measurement uncertainty and error contaminated signals, and a proven technology for representation of heuristic knowledge and automation of subjective manual operations. Neural Network Technology, on the other hand, provides a valuable tool for modelling and prediction of non-linear and difficult processes. A brief summary of Fuzzy Logic and Neural Network principles is presented to provide a basis for the introduction of two applications, one in Fuzzy Logic and the other utilising a Fuzzy Neural Network. The applications are part of a major project aiming to develop a new generation of fully automated control systems for Autocone cone crushers. The Fuzzy application is used in conjunction with a number of novel wear sensors to predict the rates of liner wear under various operational conditions, including feed size, moisture content and crusher's setting. The Neural Network application has been developed as part of a Knowledge-Based Condition Monitoring System and provides a novel technique for vibration analysis of the crusher as a fault diagnosis routine.

Twin-Screw Extrusion Cooking of Small White Beans ( Phaseolus vulgaris)

Dry small white beans (Phaseolus vulgaris) were ground and processed through a twin-screw extruder using three screw configurations of increasing energy intensity. Products were made over a moisture range of 150-250 g/kg, and barrel temperatures of 56-184°C. Results were examined by means of response surface methodology. Extrudate properties were significantly dependent (P < 0.10) on both the screw configuration and extrusion conditions used. In general, as the energy intensity of the configuration increased, expansion ratio, starting viscosity and hot viscosity increased, while bulk density, ending viscosity, and trypsin inhibitor activity decreased. All properties could be mathematically described as a function of the feed moisture content, the die temperature, and the specific mechanical energy consumption (SME) in Wh/kg, as determined on an 'as is' basis. R 2 and overall P values ranged from 0.708-0.999 and 0.001-0.40, respectively. Residual trypsin inhibitor activity in the extruded products was low (<15%), and values below 10% were easily obtained. Trace amounts of ungelatinized starch granules could be found in all samples.

Mycoflora of the toxic feeds associated with equine leukoencephalomalacia (ELEM) outbreaks in Brazil.

The mycoflora of 39 feed samples associated with 29 Equine Leukoencephalomalacia (ELEM) outbreaks was studied from 1988 to 1990, in Brazil. Microbiological examination indicated Fusarium spp. as the most frequent mold which occurred in 97.4% of samples followed by Penicillium spp. in 61.5% and Aspergillus spp. in 35.9%. The moisture content of feed implicated in death of horses was above 15% which can favor the development of Fusarium spp. From the genus, F. moniliforme was the predominant species with an occurrence of 82.0%. Two additional species, not commonly associated with animal toxicosis, were isolated in low frequency, F. proliferatum (12.8%) and F. subglutinans (2.6%). It is important to emphasize that the isolation of F. proliferatum and F. subglutinans from feed obtained from the epizootic areas has not been documented previously in Brazil.

Voidage of ferrous sinter beds: new measurement technique and dependence on feed characteristics

A new technique for measuring the voidage of a packed bed of wet deformable granules is described. Rather than attempt to measure voidage in situ, the voidage is calculated from accurate measurements of bed bulk density and separate measurement of granule apparent density by kerosene displacement. The technique is reproducible to ±0.005 void fraction. This technique is used to study in detail the factors which determine the voidage of packed beds of granulated ferrous sinter feed. 10 sinter feed blends are used varying the type of ore (7 ores), feed size distribution and moisture content (3.5% to 8%). As moisture content increases, bed voidage passes through a maximum. At low moisture contents, added water reduces the spread of the granule size distribution and increases the voidage. At higher moisture contents, granule deformation becomes important. Granules become more deformable as moisture content increases and the bed voidage drops. The key parameter which affects granule deformation is the granule layer mass to nuclei mass ratio ( R). All blends show the same relationship between R and voidage. Voidage decreases with increasing R before approaching an asymptotic value for large values of R. The effect of feed particle size distribution, moisture holding capacity and moisture content on voidage can be explained by their effect on the layer mass to nuclei mass ratio during granulation. Hence, with the aid of a suitable granulation model, the effect of feed blend properties and granulation conditions on bed voidage can be predicted.

Modeling and process control of twin-screw cooking food extruders

Twin-screw extruders exhibit highly non-linear and interactive dunamic behavior which makes their modeling and control difficult. Transfer function models determined from experimentally observed behavior are not only adequate in capturing the dynamics of the extrusion process, but are also invaluable tools in the design of multivariable control strategies for extruders. Suitable forms of transfer function models are taken from the literature to characterize a typical process used in cornmeal extrusion. The parameters for the transfer function models are also adapted from the literature and are used as an example in process control analysis and design. The degree of process loop interactions expected in this extrusion process for various controlled variable/manipulated variable pairings is studied using the relative gain array (RGA) technique. For minimal interaction, the MIMO system with screw speed and barrel heating as manipulated variables and product temperature and motor torque as controlled variables was found best. This system, using feed rate and moisture content as input disturbances and with realistic constraints on the manipulated variables, was simulated using standard software for controlled system performance. PID controllers without additional decoupling gave adequate performance results for various controlled system requirements.

Effect of temperature, feed moisture, and pH on protein deamidation in an extruded wheat flour

The effect of three parameters on deamidation levels during twin-screw extrusion of wheat flour was studied: temperature, feed moisture content, and pH. This was accomplished by generating three sets of extrudates. The first set varied temperature (130, 155, and 170 o C), the second set varied feed moisture content (20%, 25%, and 30%), and the third set varied pH of the liquid feed (3.0, 7.0, and 12.0). In each set all other parameters were held constant. It was found that increases in temperature and feed moisture enhanced deamidation and that deamidation was also favored at extremes of pH

Recovery of sulfadimidine from pig feeds

The poor analytical recovery of sulfadimidine from medicated pig feeds was investigated by high-performance liquid chromatography (HPLC) using unlabelled and 14C-labelled sulfadimidine. In addition, autoradiographic studies of 14C-labelled sulfadimidine binding in feeds was investigated. The HPLC studies using unlabelled sulfadimidine showed that there was an inverse relationship between feed moisture content and sulfadimidine recovery. Feeds with high moisture content (18% m/m) gave lower recoveries than both control feeds (12% m/m) and feeds with low moisture content (5% m/m). Studies using HPLC with both ultraviolet and radioactivity detection showed no evidence for degradation products of sulfadimidine. Autoradiographic studies showed that the non-recovered drug was dispersed throughout the feed. A hypothesis is proposed to account for the poor recoveries.

Effects of extrusion variables and starch modification on the puffing characteristics of yam ( Dioscorea alata) flour

The viability of extruding yam flour and the effects of extrusion temperature, feed moisture content, particle size and added amylose or amylopectin on the puffing characteristics of yam flour were investigated. Extrusion temperature < 100°C, feed moisture content >10% and any level of added amylose depressed product expansion. Product firmness and density decreased with increasing extrusion temperatures but increased with increasing feed moisture content above a critical limit of 9%. In general, feed particle size and addition of amylopectin did not affect the characteristics of yam flour extrudates. Yam flour can be successfully extruded with maximum expansion at a feed moisture range of 8–10% using extrusion temperatures of 100–115°C.

Thermal analysis of rotary kiln incineration: Comparison of theory and experiment

A comprehensive heat-transfer model and associated simplified scaling laws are developed and verified using a pilot-scale, directly fired rotary kiln with a slumping bed of dry or wet, 6-mm clay sorbent particles. The kiln operating conditions examined include: rotation rate (0.1–0.9 rpm), percent fill fraction (3–8), feed moisture content (0–20 wt. %), and inner-wall temperature (190°–790°C). The model is used to determine the relative importance of several heat-transfer mechanisms, including radiation, gas-to-solid convection, and wall-to-solid convection. Simple scaling laws are also developed for water vaporization. Generally good agreement is obtained between theory and experiment without adjusting any model parameters. Further, the simplified scaling laws provide a reasonable estimate of the pilot scale performance. The key conclusions of this study for kilns at the conditions examined are (1) water exerts a profound effect on the solids thermal profile, (2) simple geometrical scaling is not sufficient, (3) the assumption of a well mixed (radially isothermal) solids bed for the heat transfer analysis is appropriate, (4) a dimensionless group, which is a function of temperature, can be defined giving the relative importance of radiative and convective modes of heat transfer, and (5) moisture vaporization rates can be roughly approximately by assuming that the water vaporizes at the boiling point at a rate controlled by the rate of heat transfer to the bed. The implications of the scaling laws for scale-up and kiln design are also examined.

FACTORS AFFECTING EXTRUSION CHARACTERISTICS of EXPANDED STARCH-BASED PRODUCTS

Effect of feed moisture, oil, protein, sugar, salt, grain size and barrel screw speed on expansion index, torque, pressure, texture, output and final moisture of extruded puffed products were studied. Sugar, salt, and oil improved expansion of the product. Increased feed moisture, protein, sugar, salt and barrel screw speed favorably decreased the torque or pressure in the extruder, and improved the texture of the product. the final moisture in the product was only related to the feed moisture and oil content of the raw material. Reducing grain size increased the expansion, hardness and output of the product and reduced the extruder pressure. All these factors probably influenced the extrusion characteristics of expanded products by affecting the starch-starch interaction. Viscosity studies on the expanded starch indicated that water, protein and sugar decreased the dextrinization of the starch during puffed extrusion, while salt increased the dextrinization.

Feedforward control model for a twin-screw food extruder

Corn meal was puffed in a co-rotating twin-screw Baker-Perkins (50 mm) food extruder. Step tests were used to study the process dynamics. Dynamic models were developed using transfer functions. The die pressure appears to be the best controlled variable for a food extrusion automatic control strategy. Simulation studies showed that feedforward can be used to reduce the effect of feed rate and feed moisture content variation on the die pressure, and it is therefore recommended for food extrusion automation. In view of the complexity of the process (disturbances, non-linearities) adaptive control seems to be more suitable for food extruders than classical PID controllers.