bluuebunny/crossref_metadata_2025 huggingface dataset:
NEW MELT CONVEYING MODELS FOR A SINGLE SCREW EXTRUDER1
Authors: LI Y. , HSIEH F.
Published: February 2007

The flow theory in an extruder is fundamental to the study of extrusion technology. Present analytical solutions of the flow theory used in many studies give significant overpredictions of the volumetric flow rate due to erroneous boundary conditions used. Modified flat plate models with and without considering side wall effect and a coaxial cylinder model for Newtonian fluids were derived in this study using new boundary conditions confirmed by Choo et al. (1980). Using experimental data from published literature, it was found that the volumetric flow rates in the extruder were better predicted by these models than the numerical solutions or the original analytical solutions.
A RESEARCH NOTE COMPRESSIVE STRESS‐STRAIN RELATIONSHIPS of AGGLOMERATED INSTANT COFFEE1
Authors: NUEBEL CHRISTOPH , PELEG MICHA
Published: February 2007

Shallow beds (3–9 mm) of two commercial agglomerated spray dried instant coffees were compressed using a Universal testing machine. the stress‐stress relationships had the sigmoid shape characteristic of cellular solids and could be described by a four parameter model originally developed for solid foams. the magnitude of the model parameters was less sensitive to the relative humidity level at storage in the range of 11–65% than to the bed's thickness. the jaggedness of the stress‐strain relationship is a manifestation of the particles brittleness and crumbliness and it is considerably reduced when they are plasticized, as a result of moisture uptake, for example. the degree of jaggedness, determined in the normalized (dimensionless) stress‐strain relationships, could be qualified and compared in terms of an apparent (“natural”) fractal dimension. It was calculated from the linear region of the corresponding Richardson plots using the “blanket” algorithm. This apparent fractal dimension, however, was only a relative measure of jaggedness, since both the scales and resolution of the mechanical signatures were arbitrarily selected. the jaggedness of the individual agglomerates signatures could not be directly inferred from those of their assemblies, primarily because the effects of averaging and the bed's cushioning could not be separated.
INACTIVATION ofSACCHAROMYCES CEREVISIAEIN APPLE JUICE BY SQUARE‐WAVE and EXPONENTIAL‐DECAY PULSED ELECTRIC FIELDS
Authors: ZHANG QINGHUA , MONSALVE‐GONZÁLEZ ADELMO , QIN BAI‐LIN , BARBOSA‐CÁNOVAS GUSTAVO V. , SWANSON BARRY G.
Published: February 2007

With equivalent electrical energy input, inactivation of microorganisms by pulsed electric fields depends on pulse waveform. Exponential‐decay and square‐wave pulsed electric fields were selected to treatSaccharomyces cerevisiaesuspended in apple juice. A parallel‐plate static treatment chamber with 25 ml volume and 0.95 cm electrode gap was used. Peak electric field and pulse electric energy input were 12 kV/cm and 260 Joules per pulse for both waveforms. Both waveforms were found effective in the microbial inactivation. However, inactivation ofS. cerevisiaetreated with square‐wave pulses was greater than yeast treated with exponential‐decay pulses. For the purpose of food pasteurization, square‐wave pulsed electric fields may result in significant energy savings compared to exponential‐decay pulses.
A COMPARISON of ALTERNATIVE FORMULATIONS FOR the PREDICTION of ELECTRICAL HEATING RATES of SOLID‐LIQUID FOOD MATERIALS
Authors: ZHANG LI , FRYER P.J.
Published: February 2007

The modelling of the electrical heating of solid‐liquid food mixtures is an active area of research, reflecting its new importance as a commercial process. Two published models for electrical heating have been compared, and the accuracy of the use of circuit analogies for the prediction of heating rate was examined. It is shown that circuit analogies may not predict the heating rate correctly, especially at low solids fraction. the applicability of circuit analogies for the calculation of the heating effects of isolated particles of significantly different conductivity to the medium is discussed.
MATHEMATICAL MODELING of SOLID‐LIQUID TWO PHASE TUBE FLOW: an APPLICATION to ASEPTIC PROCESSING
Authors: LIU YANSHENG , ZURITZ CARLOS A.
Published: February 2007

The sizing of holding tubes for continuous sterilization of foods containing large particles is affected by the flow behavior of the suspensions. Velocities of carrier fluid and model food particles in holding tube flow were numerically simulated through an iterative solution of the Navier‐Stokes equations and particle dynamic equations in three dimensions. the Lagrangian approach was used to predict the individual particle trajectories under multiparticle tube flow. the physical domain included two straight tubes connected with a 180° bend. the system had an upward inclination of 1.194° (0.25 in./ft of straight run). the assumptions considered included Newtonian carrier, spherical and neutrally buoyant particles, and 10% v/v particle loading. the results indicate that the particles have a significant back‐influence on the fluid flow field. the 180° bend strongly affected both fluid and particle flow fields, which further reinforced the interaction of the two phases. the fastest particle velocities were less than the fluid streamline velocities passing through the particles' center. the radial positions of the particles on the cross section of the holding tube changed very little in the first straight section, but experienced a significant shifting in the bend and second straight‐tube sections due to secondary flow. the residence times of particles under secondary‐flow effect are therefore different from those obtained under straight tube‐only flow.
MATHEMATICAL MODELING of PARTICULATE TWO‐PHASE FLOW IN A HELICAL PIPE
Authors: LIU YANSHENG , ZURITZ CARLOS A.
Published: February 2007

The design of helical tubes for continuous sterilization of low‐acid foods (pH > 4.6) containing large discrete particles depends on the knowledge of the flow behavior of the suspended particles. the flow behavior of a carrier fluid with suspended solid spherical particles in a helical tube was numerically simulated through an iterative solution of the Navier‐Stokes equations and the particle dynamic equations in three dimensions. the Lagrangian approach was used to predict the individual particle velocities and trajectories under solid‐liquid two‐phase flow situation. the results indicate that the residence time distribution of the particles in helical tube flow was narrower than in a conventional holding tube (consisting of two straight tubes connected with a 180° bend). Also, the average velocity of the particles was closer to the average velocity of the carrier fluid in the helical tubes. the secondary flow induced by the tube curvature greatly reduced the axial dispersion of the particles. There was a substantial particle influence on the fluid flow field. the pressure drop in helical tube was 18% higher for single‐phase flow and 51% higher for two‐phase flow than in conventional holding tube of equal length.
RESIDENCE TIME DISTRIBUTION of CYLINDRICAL PARTICLES IN A CURVED SECTION of A HOLDING TUBE: the EFFECT of PARTICLE SIZE and FLOW RATE1
Authors: SALENGKE S. , SASTRY S.K.
Published: February 2007

The residence time and the residence time distributions of cylindrical particles (density 1130 kg/m3 and particle concentration 20% v/v) in a U‐bend of 22 cm radius of curvature were studied. All experiments were conducted at room temperature and with an aqueous solution of sodium carboxymethylcellulose (0.5% CMC) as the carrier medium. Two levels of particle size (11 and 20 mm) and three levels of product flow rates (0.66 × 10−3, 0.81 × 10−3, and 0.97 × 10−3 m3/s) were used. the results obtained from this study showed that the mean and the standard deviation of the normalized residence time of particles decreased as either particle size or flow rate was increased. the E(θ) and F(θ) curves indicated that flow profile of particles approached the plug flow profile as the particle size or the flow rate was increased. Results obtained from regression analyses revealed that the mean and the standard deviation of the normalized residence time were significantly influenced by particle Froude number and most strongly by particle‐to‐tube diameter ratio.
METHOD FOR MEASURING CO2 ABSORPTION IN CO2 and N2 PACKAGED FRESH MEAT1
Authors: ZHAO YANYUN , WELLS JOHN HENRY
Published: February 2007

Headspace gas composition of meat stored in modified atmosphere packaging (MAP) undergoes dynamic changes as a result of packaging film permeability, postmortem metabolic activity, CO2 absorption in water and lipid, and bacteria growth and respiration. A combined analytical and experimental method was developed to investigate CO2 absorption by packaged fresh meat in a gas‐impermeable environment and during isothermal storage. the ideal gas law was used as a theoretical basis and a gas‐impermeable and constant‐volume chamber was constructed to evaluate the theoretical derivation. Changes in headspace pressure caused by dynamic interactions between beef and MAP atmospheres were monitored to predict concentration changes of CO2 within the chamber. the proposed methodology for measuring CO2 concentration changes was confirmed by gas analysis and proved valid for prediction of headspace CO2 concentration changes in MAP gas‐impermeable systems within the range of initial gas composition 20% to 100% CO2 balanced with N2, at temperatures ranging from 3 to 13C, and an initial headspace pressure of 155 kPa.
MILK COAGULATION CUT‐TIME DETERMINATION USING ULTRASONICS
Authors: GUNASEKARAN SUNDARAM , AY CHYUNG
Published: February 2007

A nondestructive method of determining milk coagulation cut‐time was investigated. Velocity and attenuation of ultrasonic waves through coagulating skim milk were measured after rennet addition. the ultrasonic attenuation measurements were found suitable for distinguishing the effect of different experimental variables (three levels of temperature, rennet and CaCl2). Based on the rate of change of attenuation during coagulation, a turning point was defined at which the attenuation rate change was ‐0.1 neper/m/min. the cut‐time was proposed to be 20 min from the time the turning point was observed. the cut‐times predicted by this criterion were statistically similar to those predicted by the manual method currently used in the industry.
FLUID to PARTICLE CONVECTIVE HEAT TRANSFER COEFFICIENT IN A HORIZONTAL SCRAPED SURFACE HEAT EXCHANGER DETERMINED FROM RELATIVE VELOCITY MEASUREMENT1
Authors: BALASUBRAMANIAM V.M. , SASTRY S.K.
Published: February 2007

Liquid‐to‐particle convective heat transfer coefficient (hfp) between fluid and particle was investigated in continuous flow through a horizontal scraped surface heat exchanger. the relative velocities between fluid and particle were measured, and hfp calculated from well known correlations. Heat transfer coefficients increased with increasing flow rate, rotational speed, and decreased with increasing carrier medium viscosity and particle size. the measured relative velocities during flow visualization studies ranged from 0.04 to 0.29 m/s with corresponding hfp values of 597 W/m2°K and 1975 W/m2°K, respectively. Even with the most conservative correlation, Nusselt numbers ranged from 12.1 to 49.7; significantly greater than the value of 2.0 for a sphere in a stagnant fluid.
RESEARCH NOTE ESTIMATING SHEETING ROLL CLOSING FORCES THROUGH MEASUREMENT of ROLL POWER CONSUMPTION
Authors: LEVINE LEON
Published: February 2007

An important factor in the design of the sheeting operation used in the snack food and bakery industries are the forces exerted on the rolls as a result of the pressure developed between the rolls. These forces can cause significant mechanical deflections that result in nonuniform products being produced across the width of the rolls. Unfortunately, measurements of closing forces on operating sheeting systems can be difficult to obtain. This note illustrates a simple method for estimating the difficult to obtain sheeter closing forces from more easily obtained power measurements. A limited quantity of data confirms the accuracy of the procedure.
EFFECT of SCREW CONFIGURATION and SPEED ON RTD and EXPANSION of RICE EXTRUDATE
Authors: LEE SIEW YOONG , MCCARTHY KATHRYN L.
Published: February 2007

The influence of screw configuration and screw speed on the residence time distribution and product expansion was determined for rice meal processed in a corotating twin screw extruder. Screw speed had strong effect on the E(t)‐ and F(t)‐diagrams, with the mean residence time varying inversely with screw speed from 206 s to 256 s. the F‐diagram was modeled by the combination of perfect mixing and plug flow. the P estimates, which express the fraction of material in plug flow, varied inversely with screw speed from 0.41 to 0.55 for the operating conditions in this study. Both screw configuration and screw speed were statistically significant to the expansion ratios of rice extrudate, with the expansion in the height ranging from 2.98 to 4.13.
ESTIMATION of CONVECTIVE HEAT TRANSFER BETWEEN FLUID and PARTICLE IN CONTINUOUS FLOW USING A REMOTE TEMPERATURE SENSOR1
Authors: BALASUBRAMANIAM V.M. , SASTRY S.K.
Published: February 2007

The convective heat transfer coefficient (hfp) between fluid and particle in continuous tube flow was estimated using a temperature pill, a remote electronic temperature sensor which uses a quartz crystal as the temperature sensing element. the temperature history of a particle (with temperature pill mounted within) was monitored as it moved through a test section. A finite element algorithm was then used to back calculate hfp from the time‐temperature data. the value of hfp ranged from 134 W/m2K to 669 W/m2K (Nu=3.6 to 17.3) over a fluid generalized Reynolds number range (restricted by experimental constraints) from 19 to 196.8. As expected, hfp decreased with increasing carrier medium viscosity and increased with increasing flow rates. Even with several conservative factors at play, the lowest Nusselt number was greater than the 2.0 expected for a spherical particle in a stagnant fluid. Potential applications of the technique include noninvasive measurement of the temperature (and hfp values) of the particles moving within a fluid stream in otherwise inaccessible locations.
APPLICATION of ARTIFICIAL NEURAL NETWORKS to INVESTIGATE the DRYING of COOKED RICE
Authors: RAMESH M.N. , KUMAR M.A. , RAO P.N.SRINIVASA
Published: February 2007

Commercially available neural networks software was applied for prediction of processing parameters with reference to the product quality of the dehydrated cooked rice. These results were verified with experimental data. the experimental results indicate good concurrence with the predicted data. A small capacity vibrofluidized bed drier was used to conduct the experimental studies. the inlet air temperature of 160C to 180C, the inlet air velocity of 3 to 6 ms−1 and the resident time of 5 to 8 min were used in the study. the optimized process parameters were identified. the operation of the neural network model is discussed. the trained model can be applied in a nonlinear model predictive scheme to control the product moisture content.
THERMAL INACTIVATION of PECTINESTERASE IN PAPAYA PULP (pH 3.8)
Authors: MAGALHÃES M.M. DOS A. , TOSELLO R.M. , DE MASSAGUER P.R.
Published: February 2007

In order to establish the thermal process required by acified papaya pulp (pH 3.8) var “formosa”, a study was carried out on the kinetics of thermal inactivation of the heat resistant enzymes present in the pulp. Since no peroxidase activity was detected, the study was focused on pectinesterase.

The heat inactivation curves at 75, 77 and 80C showed a change in slope indicating the presence of two different portions of the enzyme, one heat labile and the other heat resistant. the decimal reduction times (D value) of pectinesterase were 0.8, 0.3 and 0.2 min for the heat labile portion and for the heat resistant portion 16.7, 7.2 and 3.7 min, respectively.

The temperature‐dependency factor for the heat labile portion was 9.2C and 7.8C for the thermostable portion, while the activation energies were 258.3 and 304.4 Kj/mol. These values were within the range of 167.5–418.7 Kj/mol reported in the literature for the thermal inactivation of enzymes. Thermal destruction studies with Clostridium pasteurianum, conducted at the same temperatures used for the inactivation of the enzyme, showed that the heat resistant portion of pectinesterase presented greater thermal resistance and should be used as target for the establishment of the required process.
ELECTRIC FIELD EFFECTS ON THE THERMAL CONDUCTIVITY OF MILK CHOCOLATE DETERMINED USING THE “MIRROR IMAGE METHOD”
Authors: DAUBERT C.R. , STEFFE J.F. , LLOYD J.R.
Published: February 2007

Electrorheological fluids exhibit changes in flow properties when exposed to an electric field. Generally, these fluids display an increase in apparent viscosity and a greater yield stress in the presence of a voltage. Another attribute of some electrorheological fluids is the ability to enhance heat transfer, allowing for greater control over heating and cooling unit operations. This paper examined the effects of an applied voltage on the thermal conductivity of molten milk chocolate, a material known to be an electrorheological fluid. The method used to measure the thermal property was based on the “mirror image’ concept. In this technique, identical disks sandwich a heat source providing a constant heat flux directed evenly between the two sides. Knowing the heat flux and the boundary temperatures of the sample gap, an analytical solution was used to calculate the thermal conductivity and specific heat. An applied electric field of up to 450 V mm−1 at 60 Hz was found to have no significant effect on the heat transfer properties of milk chocolate. The thermal conductivity was found to have an average value of 0.163 W m−1 K−1 over a temperature range varying from 25 to 60C. The measurement technique, however, proved to be a rapid method for determining thermal properties that may be useful in investigating other liquid foods.
PHYSICAL AND COOKING PROPERTIES OF MICRONIZED LENTILS
Authors: CENKOWSKI STEFAN , SOSULSKI FRANK W.
Published: February 2007

The potential for reducing the cooking time of lentils by micronization was studied. The effect of infrared heat and initial seed moisture on the internal temperature of lentil seeds was monitored up to the stage of seed browning. The seed physical properties, water uptake by seeds, cooking time and starch properties were determined. The cooking time was shortened from 30 min for the control seeds to 15 min for lentils adjusted to 25.8% wb moisture content and micronized for 55s to 18.0% wb moisture. Micronization was effective in gelatinizing and solubilizing 45 to 65% of the starch in the lentil seed, depending on the initial seed moisture content.
NONLINEAR PREDICTIVE OPTIMAL CONTROL OF A BATCH REFRIGERATION PROCESS
Authors: TRELEA IOAN‐CRISTIAN , ALVAREZ GRACIELA , TRYSTRAM GILLES
Published: February 2007

A predictive optimal control algorithm for a fruit refrigeration process is described. The future inlet air temperature profile is optimized on line, taking into account the most recent process measurements, and thus introducing feedback. The optimality criterion is directly based on economic costs. Technological and product quality constraints are included. The future control profile optimization requires long term predictions of process variables evolution, achieved using a physical model of the plant. The model is adjusted on line in order to account for unmeasured disturbances and poorly known product properties. Both the optimality criterion and the plant model are nonlinear. The approach is experimentally validated on a pilot scale refrigeration plant. Economic benefits from using an optimal, rather than a traditional constant temperature profile are discussed, revealing the importance of the process configuration. Robustness of the control algorithm with respect to modeling errors, measured and unmeasured disturbances, and temporary plant failures is demonstrated.
INFUSION OF CITRUS FRUIT PEEL BY LOW‐PRESSURE FLUID INJECTION USING A SELF‐SEALING NOZZLE
Authors: PAO STEVEN , PETRACEK PETER D.
Published: February 2007

Removal of citrus peel is facilitated by infusion of water into the peel. A low‐pressure fluid injection (LPFI) technique was developed to improve infusion efficacy. Water under low pressure (340 to 1700 mbar) was forced through an opening formed near the equator of the fruit. The water spread uniformly throughout the albedo before exiting through an additional hole made on the opposite side of the fruit. Increasing pressure and flow rate reduced injection time, but excessive levels created high internal pressures that occasionally caused peels to rupture. A rubber bulb with an orifice at the tip created a nozzle that produced a water‐tight interface with the fruit during injection.
DESIGN AND SELECTION OF PROCESSING CONDITIONS OF A PILOT SCALE CONTACTOR FOR CONTINUOUS OSMOTIC DEHYDRATION OF CARROTS
Authors: QI H. , LeMAGUER M. , SHARMA S.K.
Published: February 2007

A pilot‐scale belt type osmotic contactor was designed and installed in a continuous osmotic dehydration process to obtain maximum water removal from fruits and vegetables with a minimum contact time. The carrot was chosen as a representative vegetable and a ternary mixture of sucrose/sodium chloride/water with total solids concentration of about 50 to 55% was chosen for the osmotic solution. The experimental results showed that the optimum condition was found to require a 44% sucrose/7% sodium chloride aqueous solution with 16 min of contact time which gave a water loss of 26% and a highest ratio of water loss over solids gain (about 9) among different treatments. It is concluded that the continuous type of contactor can have potential applications in the food industry.
RESIDENCE TIME DISTRIBUTION (RTD) AND GOODNESS OF MIXING (GM) DURING CO2‐INJECTION IN TWIN‐SCREW EXTRUSION PART I: RTD STUDIES
Authors: SINGH BHAJMOHAN , RIZVI SYED S.H.
Published: February 2007

The residence‐time distribution (RTD) studies are needed to characterize mixing conditions, flow patterns, and the extent of conversions and reactions of the biopolymers in any plasticating or cooking extruder. For the supercritical fluid extrusion process (SCFX), mixing of the fluid and starch‐based biopolymers is an important step affecting cell nucleation and growth. RTD was studied in the mixing zone of the extruder, where CO2 and gelatinized starch are brought together. Three levels of each of the process variables (screw speed and CO2 injection pressure) were investigated, using specially designed apparatus for color‐dye injection, and a die‐restrictor to change the pressure profile and hold up volume in the extruder. Control RTD plots were for no CO2 injection conditions at the same pressure, and the RTD of the full extruder section. Experimental RTDs were evaluated by: (1) the Wolf‐White model, (2) a cascade of continuously stirred reactors (CSTR) model and (3) a model based on plug‐flow in series with cascade of CSTRs. The last approach was most successful in capturing all aspects of the observed RTD curves including their tails. Injection of CO2 at the highest pressure (110.3 bar) increased the RTD compared to no CO2‐injection conditions. There were significant differences in the plug flow component of the RTD as well as differences in average residence time as a function of both screw speed and CO2 injection pressure conditions.
SIZE AND SHAPE EFFECT ON NONUNIFORMITY OF TEMPERATURE AND MOISTURE DISTRIBUTIONS IN MICROWAVE HEATED FOOD MATERIALS: PART II EXPERIMENTAL VALIDATION
Authors: VILAYANNUR R.S. , PURI V.M. , ANANTHESWARAN R.C.
Published: February 2007

Experiments were conducted to determine temperature and moisture distributions in brick‐shaped, cylinder‐shaped and hexagonal prism‐shaped products. Center heating for cylindrical shapes, corner heating for brick‐shapes and surface drying in all the shapes considered were predicted by the finite element model (FEM) and were observed in the experimental data. The slow rate of heating in the case of hexagonal‐prism shaped products predicted by the FEM was validated by the experimental study. The FEM calculated moisture distributions matched the experimentally measured values closely for brick (maximum % error = 9.3% and standard error = 0.9%), cylinder (6.9% and 0.6%) and hexagonal prism (1.5% and 0.15) shaped products. The FEM calculated temperature distributions and experimentally measured values were closer in the case of brick‐shaped products (maximum % error = 24.7% and standard error = 4.3C) and cylinder‐shaped products (22.0% and 2.8C) when compared to hexagonal prism‐shaped products (57.3% and 3.3C).
DIFFUSION OF OXYGEN INTO A PACKAGED PRODUCT (APPLE JUICE) WITH SIMULTANEOUS OXIDATION OF ASCORBIC ACID
Authors: KIM J.N. , HARTE B.R. , CASH J.N. , BURGESS G.
Published: February 2007

One and three dimensional mathematical models to predict loss of quality in packaged apple juice were developed. The models were based on the mass transfer of oxygen through the wall of the package and into the apple juice, and mass transfer of ascorbic acid within the apple juice with simultaneous oxidation of ascorbic acid in the packaged apple juice. Computer programs were developed to solve the mathematical model, using the finite difference method. Concentration of the ascorbic acid in the apple juice was checked using high performance liquid chromatography. Mathematical models and computer programs were successfully validated by experimentation. The model can predict the loss of ascorbic acid in apple juice up to 50% ascorbic acid remaining. The three dimensional mathematical model is valid on block type geometric packages. The mathematical model and computer program can be modified for other geometric shapes, product morphology, and oxygen diffusion, and for other forms of product oxidation.
OHMIC HEATING OF SOLID‐LIQUID MIXTURES: A COMPARISON OF MATHEMATICAL MODELS UNDER WORST‐CASE HEATING CONDITIONS1
Authors: SASTRY SUDHIR K. , SALENGKE S.
Published: February 2007

A critical issue in the modeling of ohmic heating of solid‐liquid mixtures is the understanding of worst‐case scenarios, and in particular, the reliability of mathematical models under such conditions. This study involves examination of two alternative published formulations, one involving the use of circuit theory and a well‐mixed fluid assumption, against another formulation, involving the solution to Laplace's equation, but without convective effects. As expected, the models (and an analytical solution) yield identical results under situations where solid and fluid electrical conductivity are equal. However, when the solid is of lower electrical conductivity than the fluid, the Circuit Analogy, Mixed Fluid (CAMF) approach is shown to be more conservative than the Laplace Equation, No Convection (LENC) approach. This prediction is borne out by experimental studies, which confirm that the worst‐case scenario in ohmic heating is not necessarily associated with a stationary fluid situation. Under the less likely conditions where the solid is more conductive than the fluid, the LENC approach is more conservative than the CAMF approach. Models are also compared with respect to other features, such as practicality of use, and computational cost.
PROBABILISTIC SIMULATION OF BATCH TRAY DRYING USING MARKOV CHAINS AND THE MONTE CARLO TECHNIQUE
Authors: CRONIN KEVIN
Published: February 2007

The objective in food dehydration is to dry the product to a specified uniform moisture content. In practice, a distribution in final moisture content is unavoidable, arising from the intrinsic variability of food properties and the probabilistic nature of the food drying process. A methodology is outlined whereby the inherent stochastic dynamics of batch tray dehydration in cabinet or tunnel dryers can be modeled efficiently using Markov chains. By simulating the drying process with the model, the progressive transformation of the moisture distribution of the trays throughout the drying cycle can be quantified. Output from the model is validated with experimental drying results to test its accuracy. In addition the output of the Markov approach is compared with that of an equivalent Monte Carlo simulation model to provide inter‐model comparisons. Markov analysis can predict the variation in final moisture content and thus has the potential to help maximize the value of the dried product.
A METHOD TO CHARACTERIZE ELECTRODE CORROSION DURING OHMIC HEATING
Authors: ZHAO YANYUN , KOLBE EDWARD , FLUGSTAD BEN
Published: February 2007

A method was developed to characterize visual electrode corrosion during ohmic heating of a model system. Stainless steel 304 electrodes were energized in a 2% salt solution at room temperature of 24±1C for 10 min. The effects of Alternating Current (AC) electrical frequency and current density were examined in a frequency range of 55 to 5000 Hz and current density range of 1200 to 3500 A/m2. The ratio of colorimeter values of lightness (L)/yellowness (b) was used to quantify the degree of visual corrosion. Corrosion was most serious at low AC electrical frequencies of 55, 100, 200 Hz and at high current density of 3500 A/m2. At AC electrical frequency values above 5000Hz, corrosion reduced dramatically even as current density was increased to 3500 A/m2 and heating time extended to 1–1/2 h.
NEW METHOD FOR DETERMINING INTERNAL TEMPERATURE OF COOKING MEAT VIA NMR SPECTROSCOPY
Authors: WALTON JEFFREY H. , McCARTHY MICHAEL J.
Published: February 2007

NMR spectroscopy is used to determine fat content and internal temperature of hamburger, pork sausage, and various cuts of chicken during cooking. The temperature is determined by the frequency difference of the water and fat lines within the NMR spectrum. This method is more accurate than the absolute measurement of either peak alone. Furthermore, because the measurement relies on a frequency difference, precise control of the magnetic field is unnecessary. The hamburger and sausage data indicate an accuracy of ± 1C. The temperature accuracy for chicken is ± 5C. The difference in accuracy is due to the lower fat content of chicken. Chicken bone marrow, however, has a high fat content which could be used to measure its temperature. The speed and accuracy of this technique admits the possibility of using NMR spectroscopy on the process line to determine when these cuts of meat are sufficiently cooked and thus safe.
CRISPBREAD QUALITY EVALUATION BASED ON FUSION OF INFORMATION FROM THE SENSOR ANALOGIES TO THE HUMAN OLFACTORY, AUDITORY AND TACTILE SENSES
Authors: WINQUIST F. , WIDE P. , EKLÖV T. , HJORT C. , LUNDSTRÖM I.
Published: February 2007

Appreciation of food is based on the perception all five human senses; vision, tactile, auditory, taste and olfaction. Sensory integration of chewing resistance, melting properties, crisp sound etc. will give a further perception of the food, which is called the mouth feel. In this report, a model experiment performed on crispbread is described, which was based on information fusion from human sense analogies of olfaction, auditory and tactile. Five samples of crispbread with various hardness and flour composition were placed in a special “crush chamber”. While crushed, information corresponding to three senses could be obtained – auditory by a microphone, tactile by a force sensor and smell by leading gases from the crushed material to a gas sensor array. To evaluate the information obtained, multivariate pattern recognition methods, i.e. principal component analysis and artificial neural nets were used to search for structure and correlation in the data. It was shown that by using only the auditory information, the samples could not be separated. The tactile information alone could separate three samples, and the smell information one sample. By combining all sense analogues, all five samples could be separated.
THERMODYNAMICS OF MOISTURE SORPTION IN WINGED BEAN SEED AND GARI
Authors: FASINA O.O. , AJIBOLA O.O. , TYLER R.T.
Published: February 2007

Experimental data on sorption isotherms of gari and winged bean seeds were used to determine their thermodynamic functions (heat of vaporization, spreading pressure, net integral enthalpy and entropy). The heat of vaporization of both products reduced with increase in moisture content and approached that of saturated water at moisture contents of about 15%. Within the moisture content range of 2.0 and 18.0%, the net integral enthalpy and net integral entropy of gari were respectively higher and lower than those of winged bean seeds. The maximum net integral enthalpy for gari was 556 kJ/kg and was 335 kJ/kg for winged bean seeds. The difference in the values of the thermodynamic functions were attributed to the higher amount of oil/fat in winged bean seeds and the presence of gelatinized starch in gari.
DIELECTRIC PROPERTIES OF SHRIMP RELATED TO MICROWAVE FREQUENCIES: FROM FROZEN TO COOKED STAGES
Authors: TANAKA F. , MALLIKARJUNAN P. , HUNG Y.‐C.
Published: February 2007

Dielectric properties of shrimp (Penaeus sp.) were measured at frequencies between 0.3 and 3 GHz from ‐25 to 70C by using a network analyzer. The relationship between dielectric properties and temperature was determined at 915 MHz and 2450 MHz. Below the freezing point, the dielectric constant (ɛ′) and dielectric loss factor (ɛ″) increased rapidly with increasing temperature as ratio of frozen water in shrimp was decreasing. Above the freezing point, the dielectric constant (ɛ′) decreased as frequency and temperature increased at both frequencies. The dielectric loss factor (ɛ″) did not change significantly with temperature. The relationships between penetration depth and temperature at both frequencies were evaluated from the experimental data.
MODELING OF TEMPERATURE PROFILES UNDER CONTINUOUS TUBE‐FLOW MICROWAVE AND STEAM HEATING CONDITIONS
Authors: BAIL A. Le , KOUTCHMA T. , RAMASWAMY H.S.
Published: February 2007

Mathematical models were developed based on perfectly mixed flow (PMF), piston flow with heat diffusion (PFHD) and laminar flow (LF) approaches to predict liquid temperature history under continuous tube‐flow microwave and steam heating conditions. Two helical glass coils placed inside domestic microwave ovens (one coil in each of the two 700 W capacity ovens) or in a steam cabinet were used for heating and a spiral condenser at the exit was used for cooling. Transient and steady state mean temperatures of the fluid were experimentally measured at the exit and were compared with predictions from the mathematical models for both systems. The residence time, velocity distribution as well as temperature profiles, along the radius and the length of the tubes, were computed using the models. The PFHD and the LF models better described temperature profiles during the initial transient period, while the PMF model shovsed a better agreement with experimental data during steady staie conditions. The occurrence of secondary turbulence in the helical coil (associated with high Dean numbers) was believed to be responsible for reducing the radial temperature gradients and achieving close to “perfectly mixed piston flow” situation. A relatively larger temperature gradient across the radius was observed under microwave heating conditions than under steam heating conditions. The time‐temperature effects were integrated to predict the lethality at selected temperatures and flow rates for both continuous‐flow thermal processing.
CHARACTERIZATION OF FOOD SURFACES USING SCALE‐SENSITIVE FRACTAL ANALYSIS
Authors: PEDRESCHI FRANCO , AGUILERA JOSÉ M. , BROWN CHRISTOPHER A.
Published: February 2007

Length‐scale and area‐scale analyses, two of the scale‐sensitive fractal analyses performed by the software Surfrax
http://www.surfract.com, were used to study food surfaces measured with a scanning laser microscope (SLM). The SLM measures surfaces, or textures (i.e., acquires topographical data as a collection of heights as a function of position), at a spatial and vertical resolution of 25 μm. The measured textures are analyzed by using linear and areal tiling (length‐scale and area‐scale analysis) and by conventional statistical analyses. Area‐scale and length‐scale fractal complexities (Lsfc and Asfc) and the smooth‐rough crossover (SRC) are derived from the scale‐sensitive fractal analyses. Both measures proved adequate to quantify and differentiate surfaces of foods (e.g., chocolate and a slice of bread), which were smooth or porous to the naked eye. Surfaces generated after frying of potato products (e.g., potato chips and French fries) had similar values of Asfc and SRC, and larger (implying more complex and rougher surfaces) than those of the raw potato. Variability of surface texture characterization parameters as a function of the size of the measured region was used in selecting the size of the measured regions for further analysis. The length‐scale method of profile analysis (also called the Richardson or compass method) was useful in determining the directionality or lay of the anisotropic texture on food surfaces.
EFFECTS OF THERMAL AND ELECTROTHERMAL PRETREATMENTS ON HOT AIR DRYING RATE OF VEGETABLE TISSUE
Authors: WANG WEI‐CHI , SASTRY SUDHIR K.
Published: February 2007

Cylindrical samples of carrot, potato and yam were dried in a hot‐air dehydrator after preheating to 50C or 80C by three different heating methods (conventional, microwave and ohmic). The results showed that enhancement of drying rate increased with pretreatment temperature. Ohmic pretreatment increased the drying rate more than conventional and microwave heating. Desorption isotherms showed that in the low aw range, desorption data of preheated and raw materials were similar. However, the isotherms of preheated samples shifted when aw was high, which indicated that thermal pretreatments altered the structure, and apparently, the water distribution within these materials. For all samples, ohmic pretreatment showed stronger influences on isotherms than microwave heating, while the pretreatment effect of conventional heating was only observed for potato tissue.
ENZYMATIC HYDROLYSIS OF SOYBEAN FOR SOLVENT AND MECHANICAL OIL EXTRACTION
Authors: BARGALE PRAVEEN C. , SOSULSKI KRYSTYNA , SOSULSKI FRANK W.
Published: February 2007

Due to inefficient extractability of its low oil content, soybeans are often bypassed in village‐scale processing. Soygrits, flakes, and expanded collets were hydrolyzed by proteases, cellulases, and pectinases before oil extraction by solvent and static mechanical pressure. Driselase with multi‐enzyme activity and two proteases improved solvent extraction rates but only Driselase enhanced mechanical pressing. Up to 58% of seed oil was pressed from enzyme‐hydrolyzed flakes but 88% was pressed from Driselase‐treated collets. Either pretreatment is a feasible adjunct to mechanical pressing in small batch operations.
REAL‐TIME DUAL‐WAVELENGTH IMAGE PROCESSING FOR POULTRY SAFETY INSPECTION1
Authors: PARK BOSOON , CHEN YUD‐REN
Published: February 2007

Real‐time multispectral image processing algorithms were developed for online poultry carcass inspection. Neural network models with different learning rules (delta and hyperbolic tangent) and transfer functions (sigmoid and norm‐cum‐sigmoid) were examined using features extracted from spectral images at 540 nm and 700 nm. The classification accuracy using dual wavelength spectral images was much higher than single wavelength spectral images in identifying unwholesome poultry carcasses. The spectral image features at 700 nm were useful to identify wholesome carcasses, while the combination of spectral image features at 540 nm, 700 nm, and their ratio improved the classification accuracy of unwholesome carcasses. The optimum neural classifier utilized delta learning rule and hyperbolic tangent transfer function. The classification accuracy was 91.1% for wholesome and 83.3 % for unwholesome carcasses when the spectral images of all 540 nm, 700 nm, and their ratio were used as inputs to the neural network model.
MIXING IN SCRAPED SURFACE HEAT EXCHANGER GEOMETRY USING MRI
Authors: WANG WEI , WALTON JEFFREY H. , MCCARTHY KATHRYN L.
Published: February 2007

Mixing, as a unit operation, is a key component in the operation of scraped surface heat exchangers (SSHE) because of its importance in ensuring uniform heat treatment. In this study, two approaches were used to evaluate mixing effectiveness in a process geometry that simulates a closed type SSHE: the strain distribution function which was based on velocity profiles and statistical mixing indices based on concentration profiles. For the 1% carboxymethyl cellulose test solution under laminar flow conditions, the lower angular rotation speed and lower axial flow rate promoted mixing with respect to mixing intensity. The residence time, as characterized by the axial Reynolds Number, was the key factor for this statistic. The strain distribution function and mixing length scale were affected by the relative contribution of angular rotation to axial flow, which was expressed as the ratio of the angular Reynolds number to the axial Reynolds number. This work demonstrates the equivalence of evaluating mixedness by experimental concentration profiles and theoretical velocity profiles.
OXYGEN TRANSMISSION RATE THROUGH MICRO‐PERFORATED FILMS: MEASUREMENT AND MODEL COMPARISON
Authors: GHOSH V. , ANANTHESWARAN R.C.
Published: February 2007

Static and flow‐through techniques were used to experimentally measure the oxygen transmission rate of micro‐perforated films. The static method simulates the actual package conditions but is very time consuming. Whereas, the flow‐through method is relatively simple and takes less time to give the results, but it gave higher values than that obtained by the static method. A regression equation was developed to correlate the data obtained by these two methods. Published models for predicting gas exchange through micro‐perforations were evaluated. The predicted data by these models were compared with the experimental data obtained by the static method and the flow‐through method for six different films. The model proposed by Fishman et al. (1996) (J=‐D(c‐cA)/Lh; Lh= thickness of the film + radius of the perforation) had very good agreement with the experimental data from the static method.
MODELING THE EFFECT OF MICROSTRUCTURE ON FOOD EXTRACTION
Authors: CROSSLEY J.I. , AGUILERA J.M.
Published: February 2007

Several cases of extraction of food components were analyzed applying the diffusion theory and Fick's second law to different microstructural architectures. A mathematical algorithm was developed for a two‐dimensional heterogeneous system and programmed in MATLAB. Architectures examined include: (1) structure with straight pores, (2) flake with impermeable platelets, (3) matrix with impermeable dispersed particles and, (4) cellular material. Results show that the architecture of phases in the solid matrix is more important than parameters normally used to correct the diffusivity for structural effects (tortuosity, porosity, volume fraction, etc.). Simulated extraction curves were similar to those obtained from experimental data where an empirical effective diffusivity was calculated. These results suggest a more fundamental approach to modeling of extraction in foodstuffs based on the microstructure and local architecture.
KINETICS OF OSMOTIC DEHYDRATION IN ORANGE AND MANDARIN PEELS
Authors: CHÁFER M. , GONZÁLEZ‐MARTÍNEZ C. , ORTOLÁ M.D. , CHIRALT A. , FITO P.
Published: February 2007

The nutritional and health properties of some citrus peel components such as pectin, flavonoids, carotenoids or limonene make interesting developing processing methods to obtain peel stable products, maintaining its quality attributes, increasing its sweetness and improving its sensory acceptability. In this sense, osmotic dehydration represents a useful alternative by using sugar solutions at mild temperature. Kinetics of osmotic treatments of orange and mandarin peels carried out at atmospheric pressure and by applying a vacuum pulse at the beginning of the process were analysed at 30, 40 and 50C, in 65 °Brix sucrose, 55 °Brix glucose and 60 °Brix rectified grape must. Vacuum pulse greatly affected mass transfer behavior of peels due to the greatly porous structure of albedo. So, PVOD treatments greatly accelerate the changes in the product composition in line with an increase in the peel sample thickness. In osmotic processes at atmospheric pressure, sample impregnation occurs coupled with osmotic process, but much longer treatments are required to achieve a reasonable concentration degree which assures sample stability. Low viscosity osmotic solutions seems recommendable in order to promote both diffusional and hydrodynamic transport, in vacuum pulsed pretreatments at mild temperatures.
APPLICATION OF WLF AND ARRHENIUS KINETICS TO RHEOLOGY OF SELECTED DARK‐COLORED HONEY
Authors: AL‐MALAH KAMAL I.M. , ABU‐JDAYIL BASIM , ZAITOUN SHAHERA , GHZAWI ABD AL‐MAJEED
Published: February 2007

The rheological properties of Common Black Horehound, Globe Thistle, and Squill types of dark‐colored Jordanian honey were examined. The types of honey used were identified via assessing the source of nectar using pollen analysis (Melissopalynology). The apparent viscosity, η, was measured as a function of the shear rate, γ. In addition, the apparent viscosity was measured, at constant shear rate (6.12 s−1), as a function of shearing time. Newton's law of viscosity (i.e., τ=ηγ) was found to adequately (R2∼ 0.99) describe the flow behavior of honey samples. The apparent viscosity was found to decrease with temperature, and the temperature dependence of viscosity was contrasted versus both Arrhenius model (η=ηoeEa/RT) and WLF model (η/ηG= 10 (C1(T–T)/C2+(T–TG))). Although Arrhenius kinetics may fit the viscosity versus temperature data for the examined types of honey, nevertheless, it gives a relatively high value of activation energy that is quite comparable with, if not even larger than, that of a typical chemical reaction. On the other hand, WLF‐model was found to adequately describe the data while at the same time it gives quite reasonable values of both TG and ηG, which are in agreement with those cited in literature.
IMPINGEMENT DRYING OF POTATO CHIPS
Authors: CAIXETA ALINE T. , MOREIRA ROSANA , CASTELL‐PEREZ M. ELENA
Published: February 2007

The effect of superheated steam temperature (115, 130, and 145C) and convective heat transfer coefficient (100 and 160 W/m2C) on the drying rate and product quality attributes (shrinkage, density, porosity, color, texture, and nutrition loss) of potato chips was investigated. Furthermore, potato chips dried by impinging superheated steam (130 and 145C, h = 100 W/m2C) were compared to air dried (same conditions), commercial, and fried potato chips.

Temperature and convective heat transfer coefficient had a significant effect on the drying rate during superheated steam impingement drying. Potato chips dried at higher drying temperature and convective heat transfer coefficient showed less shrinkage, lower bulk density, higher porosity, and darker color when compared to chips dried at lower temperatures and convective heat transfer coefficients. They were also less hard and had a lower vitamin C content.

A higher rate of evaporation during the falling rate period was obtained when superheated steam drying was compared to air impingement drying. Potato chips produced using superheated steam impingement drying showed more shrinkage, higher bulk density, lower porosity, and lighter color than chips dried with air under the same temperature and with the same convective heat transfer coefficient (130, and 145C, h = 100 W/m2C). Moreover, superheated steam‐dried potato chips retained more vitamin C during the drying process.