bluuebunny/crossref_metadata_2025_split huggingface dataset:
COMPARISON OF VARIOUS METHODS TO EVALUATE FRACTURE PHENOMENA IN FOOD MATERIALS
Authors: LUYTEN H. , VAN VLIET T. , WALSTRA P. 
Published: February 2007

ABSTRACTThe usage, including eating, of foods and intermediate products normally involves large deformations. Fracture and/or yielding then become the salient features. Several methods to study the behaviour food materials at large deformations are discussed. It is shown that it is possible to measure real material properties, independent of the method and the size and shape of the test‐piece used. Results for Gouda cheese and potato starch gels are given.
CHANGES IN RHEOLOGICAL PROPERTIES OF HYDROXYPROPYL POTATO STARCH PASTES DURING FREEZE‐THAW TREATMENTS I. A RHEOLOGICAL APPROACH FOR EVALUATION OF FREEZE‐THAW STABILITY
Authors: ELIASSON ANN‐CHARLOTTE , KIM HAK RYANG 
Published: February 2007

ABSTRACTA fundamental rheological method was used to study the freeze‐thaw stability of hydroxypropyl potato starch pastes. The effect of the number of freeze‐thaw cycles on the changes in complex modulus (G*) and phase angle (δ) during heating of the thawed starch pastes was evaluated by comparing the rheological measurements with the measurements of syneresis at different centrifugal forces. The centrifugal forces influenced the detection of the first syneresis as well as the extent of syneresis, with regard to the number of freeze‐thaw cycles. When starch pastes exhibited syneresis, the G* formed a distinctive peak during heating at 52.5–53.8C. The magnitude of the peak became bigger with number of freeze‐thaw cycles. Furthermore, the results of this rheological method give information on the destabilization process and provide a simple method for detection and prediction of the extent of freeze‐thaw stability of starch paste. With this method, the effect of the storage period at –20C, and the freezing rate, on the extent of freeze‐damage of starch pastes could be investigated successfully.
DETERMINATION OF SLIP VELOCITIES IN A CONCENTRIC CYLINDER VISCOMETER WITH MOONEY AND KILJANSKI METHODS
Authors: GRIKSHTAS ROMAS , RAO M.A. 
Published: February 2007

ABSTRACTSlip velocities of 19 tomato concentrates and 5 apple sauces at cup and bob of a concentric cylinder (CC) system (MVI) were determined using two methods: (1) of Kiljanski using two CC systems, and (2) of Mooney using three CC systems. For many food samples, there were large differences in the magnitudes of slip velocities at the cup and bob calculated according to the two methods. However, corrected shear rates according to the two methods were in good agreement. Both the calculated slip coefficient of Mooney and the slip velocity of Kiljanski increased with applied shear stress according to power relationships; however, the former showed a weaker dependence on applied stress.
SLIT RHEOMETER STUDIES OF WHEAT FLOUR DOUGH1
Authors: BHATTACHARYA MRINAL 
Published: February 2007

ABSTRACTRheological properties of bread dough having different levels of added gluten (0, 2.5, 5.0 and 7.5%) were measured. The dough was forced through a slit die attached to a cylindrical container. The material functions of interest included steady shear viscosity, first normal stress coefficient in steady shear flow derived from hole pressure measurements and planar extensional viscosity as estimated from entrance pressure drop measurements. These rheological properties were correlated to the loaf volume of the baked bread. Results indicate that the first normal stress coefficient and planar extensional viscosity were affected by the gluten content of the dough and correlated well with the loaf volume. The entrance pressure drop increased with increasing apparent shear rate but entrance correction was found to decrease with apparent shear rate. Water had a greater effect on the rheological properties than gluten content. The Trouton ratio was rather large and ranged between 850 to 2000 at a strain rate of 1s‐1 and decreased with increasing extension rate for most cases.
EFFECT OF EMULSION DROPLETS ON THE RHEOLOGY OF WHEY PROTEIN ISOLATE GELS
Authors: McCLEMENTS D. JULIAN , MONAHAN FRANK J. , KINSELLA JOHN E. 
Published: February 2007

ABSTRACTThe effects of droplet size and emulsifier type on the rheology of whey protein isolate (WPI) gels containing emulsion droplets was studied. Gels were prepared by dispersing droplets of corn oil (20 wt%, d32= 0.7 – 4 μm) in a 10 wt% WPI solution (pH 7.0, 50 mM NaCl), and heating at 90C for 15 min. Gel strength was determined by measuring the stress of gels at 20% compression using an Instron Universal Testing Machine. Droplets stabilized by WPI increased the gel strength, those stabilized by non‐ionic surfactants (Tween 20 and Triton X‐100) decreased it slightly, and those stabilized by SDS decreased it drastically. Gel strength increased as the droplet size decreased for droplets stabilized by WPI, but was relatively insensitive to the size of droplets stabilized by the small molecule surfactants. These observations may be explained in terms of the interactions between the emulsifiers and the protein network. Droplets coated with emulsifiers which can be incorporated into the protein network reinforce the structure and so increase gel strength, whereas droplets coated with emulsifiers which cannot be incorporated into the protein network disrupt the three dimensional structure of the gel and decrease its strength.
COMPRESSIVE STIFFNESS AND FRACTURE PROPERTIES OF APPLE AND POTATO PARENCHYMA
Authors: KHAN ALI A. , VINCENT JULIAN F.V. 
Published: February 2007

ABSTRACTThe compressive mechanical properties of fruit and vegetable parenchyma are related to the morphology of the material such as size, shape and orientation of cells and intercellular spaces, and cellular adhesion. Uni‐axial compression tests on geometrical specimens of apple and potato flesh have shown that apple parenchyma is mechanically very anisotropic whereas potato shows no such behaviour. Apple flesh is highly orientated in the cortex into radially elongated cells and intercellular spaces. If the flesh is compressed along the rows of cells (radial) it generally fractures by a collapse of single layer of cells at right angles to the force. If the flesh is compressed at right angles to the rows of cells (tangential) it fails in shear. It is stiffer radially but tougher tangentially requiring greater deformation to fail. There is no orientation of such morphological structures in potato and hence the compressive properties are not dependent on the direction. It always fails in shear. Mature late season apples tend to be stiffer and tougher than early apples as they have smaller cells and thicker cell walls. Early season apples become mealy quickly and cracking occurs by cell separation due to the early breakdown of pectins in the weak intercellular lamellae. This makes them mechanically much weaker than late season apples where cell adhesion is strong and cracking occurs by cell rupture, a process requiring greater force and energy.
RHEOLOGICAL EVALUATION OF MOZZARELLA CHEESE BY UNIAXIAL HORIZONTAL EXTENSION
Authors: AK M.M. , BOGENRIEF D. , GUNASEKARAN S. , OLSON N.F. 
Published: February 2007

ABSTRACTRheological properties of low‐moisture part‐skim Mozarella cheese were evaluated as a function of storage time, test temperature, and deformation rate by uniaxial extension in a horizontal plane. Proteolysis of Mozzarella cheese caused marked decreases in the tensile strength and the deformability modulus, but not in the fracture strain. As the temperature increased from 10 to 40C, the fracture strain increased more than five‐fold. The strength and the deformability modulus decreased about 60 and 85%, respectively, as the cheese temperature increased from 10 to 30C. The fracture strain of the cheese did not exhibit a clear trend with the deformation rate in the range of 50–500 mm/min. However, its strength and deformability modulus increased with the increasing deformation rate.
MECHANICAL AND SENSORY ASSESSMENT OF THE TEXTURE OF REFRIGERATOR‐STORED SPRING ROLL PASTRY
Authors: SIM B.J. , LUCAS P.W. , PEREIRA B.P. , OATES C.G. 
Published: February 2007

ABSTRACTSpring roll (or popiah) consists of a filling surrounded by a remarkably thin pastry that is subjected to tension as it is wound around the filling. It cracks easily if stored before use. Textural perception of the pastry in the mouth is also affected. Within 1 day of manufacture, the Young's modulus of the pastry increases ten‐fold, the tensile strength and critical stress intensity factor (KIC) increase to a lesser extent, but the strain to failure decreases. In the single‐edge‐notched test (mode I fracture) and trousers tear test (mode III fracture), which gave free‐running cracks, fresh pastries were tougher than stored pastries because of blunting of the crack tip by large elastic strains. When the radii of curvature of crack tips in both fresh and stored pastries were constrained to be more equal in a cutting test, which induced out‐of‐plane shear in mode III fracture, fresh pastries were less tough than stored pastries. This paradox could be important in understanding otherwise contradictory textural assessments made by human subjects at the front versus the back of their mouth.
RHEOLOGY OF SALTED EGG YOLK
Authors: IBARZ A. 
Published: February 2007

ABSTRACTThe influence of salt content (7‐14% of weight) on the rheological behaviour of egg yolk in the temperature range 5‐60°C was studied. The samples showed rheological behaviour that may be described by the power law equation. An increase in the salt content leads to an increase in the consistency index, whereas the flow behavior index shows a tendency to decrease. The effect of temperature on the consistency may be related by an Arrhenius‐type equation in which the activation energy decreases as the salt content increases. The behaviour index does not vary greatly with temperature and there is a linear relation with the total solids content. A general equation describes the behaviour of egg yolk for the ranges of dry extract (D), salt content (C) and temperature studied:
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A MICRO‐SCALE METHOD FOR MEASURING THE HARDNESS OF HEAT‐INDUCED PROTEIN GELS
Authors: LEE S.‐P. , BATT C.A. 
Published: February 2007

ABSTRACTA micro‐scale penetrometry method for testing the hardness of heat‐induced whey protein gels was developed. The hardness of gels could be determined quantitatively on sample volumes as small as 20 μl. A needle with an outside diameter of 1.06 mm (18 gauge) weighted with a water reservoir was used to measure the force which was necessary to penetrate a gel contained within a capillary tube. In parallel, the Instron was used for compression testing of protein gels. There was a high correlation between the values obtained using an Instron (70% compression) and those obtained using a micro‐penetrometer for bovine β‐lactoglobulin gels prepared at concentrations over a range of 10‐13%. Similarly, there was a high degree of correlation for hardness measurements between both methods for gels made from either whey protein isolate or bovine serum albumin. Based upon standard curves of Instron force versus penetration force, the penetration force of whey protein gels as measured by micro‐scale penetrometry could be converted into relative Instron force units.
STUDY OF FOAM STABILITY BY VIDEO IMAGE ANALYSIS: RELATIONSHIP WITH THE QUANTITY OF LIQUID IN THE FOAMS
Authors: GUILLERME C. , LOISEL W. , BERTRAND D. , POPINEAU Y. 
Published: February 2007

ABSTRACTFoaming properties of three different protein solutions [casein ca, soybean isolate si, deamidated gluten dg] were studied. A video image camera, coupled to an apparatus designed for the study of the formation and the stability of foams, made it possible to follow the evolution of the foam textures at the same time as physical characteristics, such as the foam volume and the liquid in the foam. The texture of the images was characterized by an original mathematical procedure derived from the two‐dimensional Haar transform. A principal component analysis was then applied to the assessed texture characteristics, in order to emphasize the similarities and the differences between the foam textures. Video image analysis was found to be complementary to the physical characterization of the foams. According to the regularity and the stability of their foams, the proteins could be ranked in the following order (from the more to the less stable foams): ca, dg, si.
BITE FORCE AND SAMPLE DEFORMATION DURING HARDNESS ASSESSMENT OF VISCOELASTIC MODELS OF FOODS
Authors: PEYRON MARIE‐AGNÈS , MIOCHE LAURENCE , CULIOLI JOSEPH 
Published: February 2007

ABSTRACTThe sensory mechanisms underlying oral perception of hardness of silicone elastomers was studied using three approaches: (1) compression between parallel plates up to 10% (2) Bite forces of 10 subjects for hardness comparisons. (3) Deformations were evaluated during controlled mechanical indentations corresponding to the maximum force previously recorded. Over the mechanical stress range studied, the bite forces remained constant for soft samples and then increased for hard ones, while the resulting deformation followed an opposite variation with a decrease for soft samples and a plateau for hard ones. When considering the hardness comparisons between samples of a given series, the harder sample was detected in 10 pairs out of 17. This detection was obtained under almost constant bite force which shows that deformation should be the sensory clue for hardness perception.
SOME TENSILE CHARACTERISTICS OF BREAD CRUMB1
Authors: CHEN PENG , WHITNEY LESTER F. , PELEG MICHA 
Published: February 2007

ABSTRACTBone shaped specimens (length 83 mm, width 20 mm and the “neck” region 10 mm) cut from slices of white, brown and whole wheat breads were tested in tension using a Universal testing machine. The ends of each specimen were taped with masking tape and held by two pairs of alligator grips to avoid slippage and failure in the grip zones. The tensile parameters determined were the shape characteristics of the prefailure force‐displacement (F vs. D) curve C1, and C2, using the equation F = C1D/(C2+ D) as the model, the ultimate force and the break elongation. They were on the order of 0.2–0.7N, 9–28 mm, 0.1–0.3 N and 4–30 mm, respectively. Because of inherent nonuniformity of the bread crumb cellular structure, the data scatter was too large to enable monitoring textural changes in the breads during seven days of storage at ambient temperature. The method's performance could probably be improved if a large number of specimens were tested and/or the specimen size reduced so it can be taken from regions where the structure is more or less uniform.
FLOW BEHAVIOUR AND STABILITY OF OIL‐IN‐WATER EMULSIONS STABILIZED BY A SUCROSE PALMITATE
Authors: PARTAL P. , GUERRERO A. , BERJANO M. , MUÑOZ J. , GALLEGOS C. 
Published: February 2007

ABSTRACTThe steady‐state flow behaviour of oil‐in‐water emulsions stabilized by a sucrose palmitate was studied. Droplet size measurements were also carried out. The influence of sucrose ester (1–10% w/w) and oil concentrations (55–85% w/w) were analyzed. Influence of ageing was also studied. The Sisko and Carreau models were used to fit the experimental results depending on oil concentration. A master flow curve was obtained for all the oil and sucrose ester concentrations studied. The resulting master curve may be described fairly well by using a form of the Carreau model which includes a shift factor for both oil and sucrose ester concentration. The influence of the oil volume fraction on the shift factor was represented by a Frankel‐Acrivos equation. A correlation between rheological properties and particle size parameters has also been established.
RHEOLOGICAL BEHAVIOUR OF THREE BIOPOLYMER/WATER SYSTEMS, WITH EMPHASIS ON YIELD STRESS AND VISCOELASTIC PROPERTIES
Authors: GIBOREAU AGNES , CUVELIER GÉRARD , LAUNAY BERNARD 
Published: February 2007

ABSTRACTFlow and viscoelastic properties of three thickened systems are presented: aqueous solutions of locust bean gum, of xanthan and a dispersion of a crosslinked waxy corn starch. Creep measurements allow investigations at very low shear rates. The existence of a yield stress is discussed. Flow was observed at low shear rates, but the starch paste exhibited pseudo‐yield stress behaviour. Dynamic measurements were performed and the relationships between flow curves and mechanical spectra are discussed.
EFFECT OF TEMPERATURE CYCLING ON THE CRYSTALLINE FORM, SIZE AND TEXTURAL PROPERTIES OF SHORTENING FATS
Authors: CHAWLA P. , de MAN J. M. 
Published: February 2007

ABSTRACTTemperature cycling significantly reduced the solid fat content, peak force and firmness. The fats with the highest level of palmitic acid were the most stable in the β' polymorphic form. Those with the lower palmitic acid content changed to the β polymorphic form on isothermal storage as well as temperature cycling. In spite of these polymorphic changes, no dramatic change in other physical characteristics occurred.
RHEOLOGICAL CHARACTERIZATION OF FLUIDS USING NMR VELOCITY SPECTRUM MEASUREMENTS
Authors: SEYMOUR JOSEPH D. , MANEVAL JAMES E. , McCARTHY KATHRYN L. , POWELL ROBERT L. , McCARTHY MICHAEL J. 
Published: February 2007

ABSTRACTThis paper demonstrates the use of the nuclear magnetic resonance (NMR) velocity spectrum to rheologically characterize a fluid‐like material in steady tube flow. The velocity spectra for four different materials, an oil‐water solution, a polyacrylamide solution, tomato juice and a paper pulp suspension are measured and qualitative agreement with theory based upon simple constitutive models is demonstrated. These materials exhibit Newtonian, power law and Bingham plastic behavior. Homogeneous and heterogeneous samples are used and the applicability to each discussed. The velocity spectra from NMR experiments allows for a nonin‐vasive method of monitoring flow behavior and as such has applications to online process monitoring of rheological properties.
FRACTURE PROPERTIES OF STARCH GELS AND THEIR RATE DEPENDENCY
Authors: LUYTEN H. , VAN VLIET T. 
Published: February 2007

ABSTRACTFracture properties of potato starch gels, consisting of swollen granules, were studied by bending, uniaxial compression, tension and cutting experiments at various strain rates. The effects of starch granule size and retrogradation were also investigated. Starch gels are very notch‐sensitive. Fracture starts from inherent defects in the gel with a size comparable to that of the swollen granules. Fracture parameters like stress and strain at fracture and fracture energy depend on the rate of deformation, in contrast with the rate independent elastic behaviour observed at small deformations. This rate dependency can be different for the different parameters. A possible explanation for the rate dependent fracture is discussed. It implies that the granular structure of the gels is essential for fracture behaviour.
MODELLING THE MECHANICAL AND HISTOLOGICAL PROPERTIES OF CARROT TISSUE DURING COOKING IN RELATION TO TEXTURE AND CELL WALL CHANGES
Authors: VERLINDEN BERT E. , DE BARSY THIERRY , DE BAERDEMAEKER JOSSE , DELTOUR ROGER 
Published: February 2007

ABSTRACTA tensile test was used to measure four mechanical properties of carrot tissue cooked under various time‐temperature conditions. A kinetic model describing the changes of these mechanical properties measured during cooking was developed. The histological properties of the rupture surfaces caused by the mechanical testing were investigated. The kinetic model was found capable of predicting the changes in the rupture mechanism of the cell walls. Determining the percentage of cell wall ruptures proved to be an accurate method to assess the textural state of carrot tissue during cooking as compared to the measurement of the mechanical properties.
MODIFICATION OF COMPRESSIVE BEHAVIOUR OF CHIOS MASTICHE GUM
Authors: KEHAYOGLOU A.H. , DOXASTAKIS G.I. , KIOSSEOGLOU V.D. 
Published: February 2007

ABSTRACTReduction of Chios mastiche hardness by additions of beeswax, lecithin or calcium stearate was studied by compression tests using an Instron machine. Beeswax and lecithin brought about a marked decrease of mastiche's resistance to compression while calcium stearate had the opposite effect. Esterification of the hard and brittle monomeric fraction of mastiche with ethanol caused a drastic modification of its texture yielding a plastic material. Its addition to mastiche at various percentages brought about a considerable decrease in the product's resistance to compression.
MECHANICAL DAMAGE INDUCED BY CONTROLLED FREEZING IN APPLE AND POTATO
Authors: KHAN ALI A. , VINCENT JULIAN F.V. 
Published: February 2007

ABSTRACTFreezing was used to induce controlled damage to apple and potato parenchyma. As the tissue freezes ice crystals form extra‐ or intracellularly, pushing the cells apart or rupturing cell walls producing large voids within the tissue. Mechanical tests (wedge penetration, tensile and compression) on specimens frozen to a certain temperature at a controlled rate and thawed show that the changes in the mechanical behaviour of the material are directly related to the degree of cell damage. As the tissue freezes, the fastest rate of tissue damage occurs between ‐3C and ‐10C. In this range there is a marked decrease in stiffness and an increase in the deformation required to cause failure. In apples, slow freezing leads to the intercellular spaces expanding, increasing their aspect ratio and hence, the anisotropy of the tissue. The increasing number of voids increases crack‐stopping and ductility; more energy is dissipated in flow elevating the fracture toughness. Toughness then decreases with further damage. This effect can be mimicked with brittle paper: fracture toughness of tracing paper initially increases with increasing number of holes punched randomly in it.
ROLE OF GRANULE SIZE AND SIZE DISTRIBUTION IN THE VISCOSITY OF COWPEA STARCH DISPERSIONS HEATED IN EXCESS WATER
Authors: OKECHUKWU PAUL E. , RAO M.A. 
Published: February 2007

ABSTRACTThe role of granule size and size distribution, measured by laser diffraction, in affecting the flow behavior and yield stress of cowpea starch dispersions (2.6% w/w) heated for various time intervals at 67, 70, 75 and 80C was studied. Flow data on the dispersions at 20C were fitted to the power law flow equation. The standard deviation of the granules described the transition of flow behavior from shear thickening (dilatant) in the early stages of gelatinization to shear thinning (pseudoplastic) in the latter stages. It was an important variable for also correlating the critical shear rate, λ˙c, for the onset of shear thickening in starch dispersions. The granules swelled to a maximum of about 3.5 X raw starch granule mean diameter and a granule mass fraction of 65%. The consistency index of the dispersions increased with granule mean diameter.