bluuebunny/crossref_metadata_2025 huggingface dataset:
STRAWBERRY BRUISING AND ENERGY DISSIPATION
Authors: HOLT J.E. , SCHOORL D.
Published: February 2007

A strong correlation was obtained between bruise volume and energy absorbed for impact and quasi‐static compression of Redlands Earlisweet and Redlands Crimson strawberries. The Redlands Earlisweet variety of strawbem'es was significantly more resistant to bruising than Redlands Crimson. Strawberry tissues was more easily bruised by slow compression than by impact for both varieties. For the same amount of energy, bruise volumes were aproximately 40% higher under slow compression.

A simple model is formulated to exptain the behavior of strawberries under compression Strawberry tissue is likened to an orderly arrangement of liquid file & spherical cells bounded by viscoelastic membranes with air filled interstitials. It is postulated that compression results in change of cell shape leading to cell wall fracture, i.e., cell bursting, in regions of high shearing stress. Distortion and bursting of cells explains the energy dissipative nature of bruising.

The work shows that energy absorbed is a good predictor of bruising and is thus a useful parameter in evaluating handling and packaging systems for strawberries.
BOOK REVIEW
Authors: SZCZESNIAK ALINA S.
Published: February 2007

Rheometers for Molten Plastics: A Practical Guide to Testing and Property Measurement. John M. Dealy.
CRACKING AND ENERGY DISSIPATION IN CABBAGES
Authors: HOLT J.E. , SCHOORL D.
Published: February 2007

Whole cabbages were subjected to impact and quasi‐static compression, and it was observed that the main type of damage was cracking through the leaf layers. In static loading the cabbages withstood very high compression loads before major cracking began, with forces between 4000‐4500 N.

On impact, cracking of cabbages occurred at drop heights of 0.25 m and greater. There is a very strong linear relationship between total leaf crack length and energy dissipated during the drop. The crack resistance of cabbage is described by both the slope of the crack length‐energy dissipative response and the intercept of the line on the energy axis.

Three energy dissipative mechanisms operate during the compression loading of cabbages; energy is stored elastically to be recovered in rebound, energy is stored to be dissipated by crack propagation, and energy is dissipated by leaf movement. The energy dissipative mechanisms can be explained in terms of the structure of the whole cabbage and leaf tissue.

Crack resistance is a useful property of cabbages. It may be used to evaluate cabbage varieties for texture and cabbage handling systems for damage.
RHEOLOGICAL CHARACTERIZATION OF TOFU2
Authors: LEE Y.C. , ROSENAU J.R. , PELEG M.
Published: February 2007

The rheological behavior of four types of tofu was evaluated through compressive stress‐strain relationships, relaxation parameters, and percent recoverable work at different strains. It is shown that tofu's deformability mode, like that of sponges, is regulated by both the solid matrix properties and internal hydrostatic pressure. Because the latter is strongly affected by the specimen geometry and the deformation rate, the dependency of mechanical parameters on these factors should be considered as an inherent characteristic of tofu's texture.
A PRACTICAL METHOD FOR TENSILE TESTING OF APPLE TISSUE
Authors: SCHOORL D. , HOLT J.E.
Published: February 2007

Granny Smith apple specimens were subjected to tensile loading at three deformation rates, 20, 50 and 100 mmXmin−1. Specimens were loaded either to failure or subjected to a load cycle less than required to cause fracture. The mode of failure observed was a sudden crack across the entire specimen perpendicular to the applied force. Unbroken specimens demonstrated considerable hysteresis losses during loading and unloading.

Apparent and real fracture resistance values were calculated from the energy dissipated during cracking and crack surface area. Apparent fracture resistance varied from 258‐300 Jm−2, depending on deformation rate, and real fracture resistance was approximately constant at 200 Jm−2. The hysteresis ratio varied from 0.13‐0.4, depending on deformation rate, and this change in hysteresis losses explained the decrease in failure stress and failure deformation as deformation rate increased.

It is postulated that fracture resistance, or the resistance to cracking is a useful tensile property of apple tissue.
EFFECTS OF MIXING SOYBEAN FLOUR DOUGHS ON THEIR DYNAMIC MODULI MEASURED IN AN ORTHOGONAL RHEOMETER
Authors: JASBERG B. K. , MUSTAKAS G. C.
Published: February 2007

An orthogonal rheometer was used to determine the dynamic loss moduli and storage moduli of defatted soybean flour doughs. Doughs of 30 to 50% moisture were prepared by mixing for 1 to 10 min in a Brabender laboratory mixing head. Both moduli decreased as dough moisture increased. Moduli increased as mixing time increased. Moduli were initially constant as percent strain increased. After 1 1/2% strain, moduli decreased with increasing strain. No effect of resting time was found.
FOOD TEXTURE AND TASTE: A REVIEW
Authors: IZUTSU TADASHI , WANI KOHMEI
Published: February 2007

The subjective measurement of food texture and the objective measurement based on a rheological model are described to clarify the relationship between texture and taste. The authors suggest that the most important sensory property is texture in foods which have relatively low flavor intensity. Additionally, from the fact that the multidimensional evaluation of palatability of foods is strongly influenced by properties requiring physical measurement, they propose the introduction of a new concept, physical taste, for making effective evaluations of food palatability. More quantitative texture studies related to food quality are required as well as research on the traditional four or five basic tastes.
RHEOLOGICAL AND CALORIMETRIC INVESTIGATIONS OF STARCH‐FISH PROTEIN SYSTEMS DURING THERMAL PROCESSING2,,3
Authors: WU M. C. , HAMANN D. D. , LANIER T. C.
Published: February 2007

During the thermal processing of starch‐surimi systems, significant rheological changes due to the sol‐gel transformation of fish proteins and the gelatinization of starch were observed by rigidity scanning. Differential scanning calorimetry (DSC), produced results which corresponded well with rheological changes. Starch gelatinization in cooked fish‐starch gels was studied by DSC. The effects of starches on the textural properties of cooked gels were dependent on their gelatinization characteristics, such as gelatinization temperature, degree of swelling and water uptake of the granules. Gels producing higher failure stress values were obtained after starch gelatinized; however, no significant effect on failure strain was observed by the addition of starch. Pregelatinized starch had detrimental effects on the gelation of fish protein, and more water was absorbed by this starch compared to non‐pregelatinized starches. Resulting gels were weaker and less deformable.
BEHAVIOR OF MOZZARELLA, CHEDDAR AND PROCESSED CHEESE SPREAD IN LUBRICATED AND BONDED UNIAXIAL COMPRESSION
Authors: CASIRAGHI E.M. , BAGLEY E.B. , CHRISTIANSON D.D.
Published: February 2007

The response of a material under uniaxial compression depends both on the bulk material properties and on the frictional effects at the sample‐platen interface. Three commercial cheeses (cheddar, mozzarella and processed cheese spread) were studied in uniaxial compression. Frictional effects at the sample surface were examined under three conditions: (1) lubrication of the sample‐platen interface; (2) bonding of the sample to the instrument platens; (3) samples neither bonded nor lubricated. The forces required to deform the cylindrical sample to a given strain level were highest for the bonded cases and lowest under lubricated conditions. The stress in lubricated compression, ρL, was calculated from Fh(πRρ2hρ)
FLOW BEHAVIOUR OF LARD AND OF ITS FRACTIONS AT 15°C. RELATIONSHIP WITH THBJRMAL BEHAVIOUR AND CHEMICAL COMPOSITION
Authors: CORNILY G. , MESTE M. LE
Published: February 2007

The rheological behaviour of lard and of its fractions at 15°C was studied by means of penetrometry and viscometry in order to characterize the variations of the yield value and of the viscosity in the temperature range from – 20 to 70°C. The Casson rheological model is suitable to describe the flow behaviour of these three fats until completely melted. The variations of the rheological parameters could be described by relationships of the form log x = a 103/T+ b. Comparison of the rheological behaviour, the thermal behaviour, determined by means of differential scanning calorimetry, and the solid fat content, determined by means of nuclear magnetic resonance, showed good relationship between the results over the whole melting range.
COMPARISON OF TWO INSTRUMENTAL METHODS WITH SENSORY TEXTURE OF PROTEIN GELS2
Authors: MONTEJANO J. G. , HAMANN D. D. , LANIER T. C.
Published: February 2007

The textural attributes of 8 different heat‐induced protein gel preparations evaluated by torsion failure testing and Instron texture profile analysis (TPA) were compared to sensory ratings by a trained texture profile panel. The gels presented a wide range of textural properties as determined by the instrumental and sensory parameters. Among the instrumental parameters, true shear strain at failure was the most frequent and significant predictor of sensory notes. Initial shear modulus and 50% compression force had the poorest correlations with sensory notes. Comparison of the two instrumental tests produced high correlations between shear stress at failure and TPA hardness; true shear strain at failure and TPA cohesiveness; and, initial shear modulus and 50% compression force. High correlations were also observed among various panel notes. Canonical correlation analyses showed that sets of linear combinations of parameters from each one of the 3 tests (torsion, TPA or sensory) were highly correlated to sets from either of the other two. Regression equations relating each of the instrumental tests to sensory notes were developed. Of the torsion failure parameters, the logarithm of true shear strain most commonly appeared in the equations. Of the TPA parameters, cohesiveness and its logarithm were the terms that were most frequent. High R2 values were obtained for regression equations developed for predicting torsion failure parameters based on TPA parameters.
EFFECT OF WATER ACTIVITY ON TEXTURE PROFILE PARAMETERS OF APPLE FLESH
Authors: BOURNE MALCOLM C.
Published: February 2007

Fresh apple with a water activity of approximately 0.99 was partially dehydrated, then equilibrated to nine water activity levels down to Aw 0.01. The water desorption isotherm, for apple is given. Instrumental texture profile analysis was performed at each Aw level. As the Aw decreased, hardness increased slowly, then rapidly at Aw 0.12 then decreased again at Aw 0.01; deformation first increased sharply then steadily decreased; springiness increased to Aw 0.33 then decreased; cohesiveness increased down to Aw 0.65, held steady to Aw 0.33 then decreased; gumminess and chewiness increased down to Aw 0.12 then decreased. Fracturability was present only at the extremes (Aw 0.99 and 0.01) and was absent at all other water activity, levels. Complex changes in textural properties occur as apple is dehydrated and most of these changes occur most rapidly near the BET monolayer level of water activity.
CORRELATING SENSORY WITH INSTRUMENTAL TEXTURE MEASUREMENTS—AN OVERVIEW OF RECENT DEVELOPMENTS1
Authors: SZCZESNIAK ALINA SURMACKA
Published: February 2007

Reasons for seeking correlations between sensory and instrumental measurements are discussed and factors which affect such correlations are pointed out. Considerable advances made in the last 1–2 decades in this field can be attributed to the general agreement that texture is a sensory and a multiple parameter quality, and to the interdisciplinary nature of new research approaches. Current trends include use of multiple correlations, attempts to understand the rheology of the human sensing apparatus, an engineering treatment of sensory perceptions, and greater attention to the rheological nature of test foods.
MECHANICAL BEHAVIOUR OF COOKED MEAT UNDER SINUSOIDAL COMPRESSION
Authors: KAMOUN M. , CULIOLI J.
Published: February 2007

The rheological behaviour of raw meat, and of meat cooked under different conditions, has been studied with sinusoidal compression in a transient state. Meat samples underwent compression perpendicular to the myofibre axis in a cell equipped with lateral walls that made it possible to limit the free strain of samples to only one direction viz. parallel (longitudinal configuration) or perpendicular (transverse configuration) with respect to the myofibres. Both raw and cooked meat exhibit visco‐elastic behaviour with a slight viscous component. Cooking meat results in both increased resistance and more elasticity. The variations in these parameters depend on the configuration and compression ratio used. With raw or slightly cooked meat, myofibrillar and connective structures can be analysed selectively in the longitudinal configuration by using compression ratios that are, respectively, nondestructive and destructive. When cooking is carried out at a high temperature, the myofibrillar resistance can be analysed preferentially in the longitudinal configuration, and connective tissue in the transverse configuration.
RHEOLOGICAL CHARACTERIZATION OF SALAD DRESSINGS. 1. STEADY SHEAR, THIXOTROPY AND EFFECT OF TEMPERATURE
Authors: PAREDES MARIA DULCE C. , RAO M. A. , BOURNE MALCOLM C.
Published: February 2007

Shear stress‐shear rate data of five commercial salad dressings at 2.0, 10.0, 18.3, 26.7, 32.2 and 43.3°C were obtained using a concentric cylinder viscometer. The power law and Casson equations were applicable for all products (r ≫ 0.98). The Arrhenius equation was applicable for the effect of temperature on the apparent viscosity at 100 s−l (r ≫ 0.97). Rheological data were obtained at a constant shear rate of 275s−l at 2.0 and 10.0° C. The results show that the Weltman equation was better than the Hahn equation in describing the thixotropic behavior of the five salad dressings.
Sensory Textural/Rheological Properties—A Polyglot List
Authors: DRAKE BIRGER
Published: February 2007

A listing is provided of 54 English terms for sensory textural/rheological properties of foods and their equivalents in 22 other languages. Translation into the other languages was done by about 50 collaborators who had a good command of English and their own language and who were well versed in textural/rheological terms.

The original purpose of this work was to provide a new approach to developing a better understanding of textural/rheological properties and words used to describe them by utilizing the principles of linguistics. It is hoped that the publication of this list will stimulate interest in a deeper analysis.
SENSORY AND INSTRUMENTAL EVALUATION OF TEXTURE OF COOKED AND RAW MILLED RICES WITH SIMILAR STARCH PROPERTIES
Authors: MUNDO ANGELITA M. DEL , KOSCO DEBORAH A. , JULIANO BIENVENIDO O. , SISCAR JULIE JOY H. , PEREZ CONSUELO M.
Published: February 2007

Three pairs of milled rices with similar starch properties (low gelatinization temperature waxy, and low gelatinization temperature low amylose, and intermediate gelatinization temperature intermediate amylose) were assessed for cooked rice properties by two industry taste panels and for raw and cooked rice properties by 30‐member Filipino consumer panels. Only slight differences in texture within pairs were noted by the two industry taste panels who had not been trained to assess boiled raw rice or waxy rice. The Filipino consumer panel gave significantly higher ranked scores for one low‐amylose variety in both raw and cooked forms. Malagkit Sungsong suman sa antala was ranked higher than modern waxy rices. Instrumental methods for translucency and whiteness of raw rice and Instron hardness and stickiness of cooked rice were not able to detect differences perceived by the Filipino consumer panels.
RHEOLOGY OF RICE‐FLOUR PASTES: EFFECT OF VARIETY, CONCENTRATION, AND TEMPERATURE AND TIME OF COOKING
Authors: RANI M. R. SANDHYA , BHATTACHARYA K. R.
Published: February 2007

Cooked pastes of rice flour showed time‐dependent shear thinning (thixotropy). Yield stresses were observed at high concentrations and high pasting temperatures. The Herschel‐Bulkley power law equation could be used with certain limitations to characterize the flow behaviour of the pastes. At low pasting temperatures (60°, 75°C), apparent viscosity increased with increasing concentration and time of cooking, and was higher for low‐amylose than for high‐amylose rice. But when cooked at 95°C, two distinct patterns were seen. At low concentrations, apparent viscosity again increased with increasing time of cooking and was higher for low‐amylose than for high‐amylose rice. But at concentrations above 7%, the pattern was totally reversed, viz., viscosity decreased with time of cooking and was higher for high‐amylose rice.
COMPRESSION STRENGTH AND FRACTURE PROPERTIES OF MODEL PARTICULATE FOOD COMPOSITES IN RELATION TO THEIR MICROSTRUCTURE AND PARTICLE‐MATRIX INTERACTION
Authors: LANGLEY KEITH R. , GREEN MARGARET L.
Published: February 2007

Foods containing particles in a matrix were modelled by setting glass spheres, varying in size and surface chemistry, and oil droplets in heat‐denatured whey protein gels. Composites containing particles with hydrophilic surfaces were much stronger in compression, the strength being dependent on particle surface area, than those with hydrophobia surfaces. The relationship between strength and particle size was compared with existing rheological and composite theories. SEM examination of fracture surfaces, resulting from compression, showed that particles with an hydrophilic surface were an integral part of the composite, failure occurring within the protein matrix. Gels made from particles with an hydrophobic surface fractured adjacent to the particle surface, indicating little or no interaction between particle and matrix.
COMPUTERIZED IMAGE ANALYSIS AND TEXTURE OF EXTRUDED BISCUITS
Authors: SMOLARZ A. , VAN HECKE E. , BOUVIER J. M.
Published: February 2007

A new method based on computerized image analysis was developed to objectively evaluate the texture of extruded biscuits. The methodology to process the visual image of the transverse cut of biscuit is presented. Structural parameters related to individual cells and the overall biscuit, are determined and discussed to discriminate between various extrudates.
SMALL AMPLITUDE OSCILLATORY TESTING (SAOT). APPLICATION TO PECTIN GELATION
Authors: BEVERIDGE T. , TIMBERS G. E.
Published: February 2007

The setting characteristics of pectin gels during cooling from 105°C to 25°C and reheating to above 100°C have been determined using a versatile food rheometer capable of small amplitude oscillatory testing. Gel strength development during cooling was linearly correlated to temperature and on reheating the gel softened initially then hardened again as the temperature exceeded about 70°C. The linear parameters (slope, intercept) describing the gel development on cooling were related to pectin concentration up to 0.85% but 1% pectin could not be distinguished from 0.85%. On cooling, 75–85% of the gel strength attainable on standing overnight was developed within 30 min. The quick set up on cooling provides the possibility of developing a rapid test method for determining pectin gel properties.
RHEOLOGICAL AND HYDRATION PROPERTIES OF POPPED RICE
Authors: MURUGESAN G. , BHATTACHARYA K. R.
Published: February 2007

The cold‐slurry viscosity, sediment volume and hydration power of popped rice, along with those of dry‐heat parboiled rice and expanded rice for comparison, were determined. Values of all these properties increased with increasing severity of processing treatment but decreased with starch reassociation. The cold slurries of these products showed time‐dependent thinning, indicating thixotropic nature. A yield value appeared beyond a certain minimum concentration. The viscosities of the products, their hydration power and sediment volume were all interrelated. The popped rice was well gelatinized with little or no starch reassociation.
GRAININESS, CRYSTAL SIZE, AND FIRMNESS OF STORED CANOLA OIL MARGARINES
Authors: VAISEY‐GENSER M. , VANE B. K. , JOHNSON S.
Published: February 2007

Canola oil margarines from two different manufacturers displayed distinctly different patterns of crystal growth and sensory graininess during 22 to 24 weeks of storage at 4°C. A seven‐member sensory panel examined both margarines biweekly and found that the product of one manufacturer remained essentially smooth throughout the storage period while that of the other manufacturer was less stable in texture. The latter was detectably grainy after 12 weeks of storage. Changes in crystal size in the less stable margarine were positively correlated with graininess frequency (r = 0.89) and with storage age (r = 0.84). The threshold for crystal size detection for the panel was estimated as 22 microns. While margarine firmness which was measured with the texturometer showed some inclination to increase with storage age, changes in crystal size explained only 31% of the variability in firmness measurements of the less stable product.
CHARACTERIZATION OF THE TEXTURAL PROPERTIES OF SPREADABLE PEANUT BASED PRODUCTS 1
Authors: MUEGO K. F. , RESURRECCION A. V. A. , HUNG Y.‐C.
Published: February 2007

Textural characteristics of two peanut butter samples and one peanut paste sample were determined using three instrumental methods and a texture profile panel. In Method A, a penetrometer with a cone‐shaped probe attachment was used. Method B involved the use of a plunger attached to the crosshead of the Instron Universal Testing Machine. Method C was a modified texture profile analysis (TPA). Instrumental measures show that peanut paste was the hardest, exhibited the greatest adhesive force but the least time to break the peanut column, and was the least cohesive. All instrumental methods were acceptable but TPA provided more information than the two other methods in describing texture. The panel rated the paste as firmest, least adhesive, spread least on the tongue, least smooth, most grainy, and most difficult to swallow. Significant correlations were found between several instrumental measures and sensory characteristics.
OSCILLATORY PROBE RHEOMETRY AS A TOOL FOR DETERMINING THE RHEOLOGICAL PROPERTIES OF STARCH‐WATER SYSTEMS 1
Authors: HANSEN L. M. , HOSENEY R. C. , FAUBION J. M.
Published: February 2007

An oscillatory probe rheometer was effective at measuring the viscosity of starch pastes and the viscoelastic properties of starch gels. Because low shear strains were applied, the integrity of the gel was not disrupted during the testing. As the starch concentration of the systems increased, the complex modulus (G*) and storage modulus (G′) increased. At 20°C, the strength of the resulting gels, as measured by log G′, was a linear function of starch concentration. Loss tangent values (G″/G′) could be used to determine the approximate temperature at which the sol became a gel. As the starch concentration of the systems increased, the temperature of the sol to gel transformation increased from approximately 35°C (5% starch) to 60°C (10% starch).
APPLICATION OF SENSORY TEXTURE PROFILING TO BAKED PRODUCTS: SOME CONSIDERATIONS FOR EVALUATION, DEFINITION OF PARAMETERS AND REFERENCE PRODUCTS
Authors: BRAMESCO NICOLE P. , SETSER CAROLE S.
Published: February 2007

Parameter definitions and reference scales of the sensory texture profiling method were examined in relation to the textural descriptions of baked products. The following textural terms were found to be pertinent to baked goods, especially to layer cakes: firmness, springiness, adhesiveness (to lip, palate, teeth), crumbliness/self‐adhesiveness, moistness, cohesiveness/deformation, moisture sorption and cohesiveness of mass. Applicable definitions were selected, and reference products representing low and high levels of these characteristics were identified. Preliminary information was obtained suggesting that the panelists' salivary flow rate and the timing of the evaluation in relation to the residence time in the mouth could be critical factors for achieving consistent responses.
A PERCOLATION ANALYSIS OF THE CONCENTRATION DEPENDENCE OF THE GELATION OF WHEY PROTEIN CONCENTRATES
Authors: STEVENTON A. J. , GLADDEN L. F. , FRYER P. J.
Published: February 2007

Although the functionality of whey proteins is difficult to determine, it has proved possible in some circumstances to model protein gelation using conventional gel theory. Such gel theory is a subset of a more general technique, that of percolation theory, which has proved successful in other branches of science. This paper reports the application of percolation theory to protein gelation. The gelation of whey proteins has been studied using oscillatory rheometry, and gel time results interpreted in terms of a Monte Carlo simulation on a model lattice, using a variety of models for gelation. A second order kinetic model was found to describe the gelation data satisfactorily.
AN ADAPTATION OF THE CASSON EQUATION FOR THE RHEOLOGY OF CHOCOLATE
Authors: CHEVALLEY J.
Published: February 2007

The generalized Casson equation with exponent m was considered. The plastic viscosities and yield values corresponding to different ranges of shear rate D were calculated for different values of exponent m between 0.5 and 1. All the plastic viscosities tend to about the same value at high shear rates, while at low shear rates all the yield values tend to the same value which is supposed to be the “true” yield value. For the exponent m = 0.6, the yield value is least dependent on the shear rate range and the yield value calculated for D > 5 sec−1 is generally much closer to the “true” yield value than the Casson value (m = 0.5). Therefore, choice of the exponent m = 0.6 is proposed.
THE INFLUENCE OF FAT, ACID, AND SALT ON THE TEMPORAL PERCEPTION OF FIRMNESS, SALTINESS, AND SOURNESS OF CHEESE ANALOGS
Authors: STAMPANONI CHANTAL R. , NOBLE A. C.
Published: February 2007

Eight cheese analogs varying in fat (10 and 25%), sodium chloride (0.5 and 2.0%), and citric acid (0.1 and 1.2%) were evaluated utilizing a time‐intensity (T‐I) procedure. Raising the salt content increased all T‐I parameters for saltiness and resulted in higher maximum intensity (MAX), longer total duration (DUR) and larger area under the T‐I curve (AREA) for sourness and firmness. Raising the acid content increased all T‐I parameters for sourness and MAX and AREA for firmness. A higher fat content resulted in softer but more sour cheese analog (by all T‐I parameters). For samples with low levels of acid or salt, sourness and saltiness MAX was reached during the 20s mastication interval. In contrast, for samples with high levels of salt or acid, MAX was attained after 20 s, but before expectoration at 30 s. As fat content increased from 10 to 25%, the cheese analogs were broken down more readily, the firmness duration decreased from 24 to 18 s.
COMPARISON OF VARIOUS METHODS TO EVALUATE FRACTURE PHENOMENA IN FOOD MATERIALS
Authors: LUYTEN H. , VAN VLIET T. , WALSTRA P.
Published: February 2007

The 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

A 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

Slip 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

Rheological 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

The 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

The 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

Rheological 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

Spring 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

The 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

A 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

Foaming 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

The 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

Bone 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

The 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

Flow 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

Temperature 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

This 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

Fracture 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

A 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

Reduction 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.