bluuebunny/crossref_metadata_2025 huggingface dataset:
SLURRY VISCOSITY AS A POSSIBLE INDICATOR OF RICE QUALITY
Authors: RANI M. R. SANDHYA , BHATTACHARYA K. R.
Published: February 2007

Forty‐one rice varieties belonging to eight quality types were examined. The viscosity of a 5% rice flour slurry dispersed in 2% carboxymethylcellulose, measured with an Ostwald capillary viscometer, was remarkably constant among varieties within the same quality type but increased significantly from type I (high‐amylose) through type VIII (little or no amylose) rice. Slurry viscosity was strongly affected by particle size, being higher for finer flour, but it appeared independent of the age of the rice after harvest. Slurry, as well as paste viscosity, was affected by kernel chalkiness in rice, chalky grains showing lower viscosity than vitreous grains. Chalky rice grains contained less amylose and hydrated more in ambient water than nonchalky ones. When ground under a constant condition, high‐amylose rice yielded slightly coarser flour than intermediate‐ or low‐amylose rice, suggesting differences in grain hardness.
DYNAMIC RHEOLOGICAL PROPERTIES OF NATURAL AND IMITATION MOZZARELLA CHEESE
Authors: NOLAN E. J. , HOLSINGER V. H. , SHIEH J. J.
Published: February 2007

Suitability of Mozzarella cheese for various products involves the measurement of rheological properties of the cheese related to its meltability. The rheology in this work is determined dynamically with a Rheometrics RDA 700 mechanical spectrometer using 25 mm diameter parallel plates fabricated from aluminum. Bonding the cheese specimen directly to the plates with cyanoacrylate ester adhesive proved the most effective in countering the problem of specimen slip. Viscosity proved sensitive to addition of calcium casenate, following an Arrhenius relationship with temperature. Both elastic and viscous components of the shear modulus increased with a 1% addition but a 2% addition decreased the elastic component below that observed for natural Mozzarella under the same conditions.
RHEOLOGICAL PROPERTIES OF AQUEOUS SOLUTIONS OF THE GUMMY EXUDATE OF ZANTHOXYLUM TESSMANNII
Authors: ORAFIDIYA 'LARA O.
Published: February 2007

Some factors that affect the rheological properties of the aqueous solutions of zanthoxylum gum were studied. The solutions exhibited Newtonian flow at low concentrations, becoming pseudoplastic as concentration increased. It was impossible to obtain a completely wetted mass at concentrations above 25% w/v. The viscosity of the gum solutions reduced irreversibly on storage and when stored at elevated temperature. However, an increase was observed with decrease in storage temperature with the solution turning into a stable gel at 4°C. The gum solutions exhibited characteristics of an acidic polyelectrolyte at dilute concentrations and in the presence of acid and salts. The expected increase in viscosity with added base was not obtained. A thick gel layer formed at interfaces between the gum solution and air, and containers and closures made with polymeric materials. This was attributed to the adsorption and interaction of the gum molecules at these interfaces.
USE OF MAGNITUDE ESTIMATION IN SENSORY TEXTURE ANALYSIS OF BUTTER
Authors: ROHM H. , ULBERTH F.
Published: February 2007

Sensory determination of butter texture properties is usually done with category scales. The present study was undertaken to evaluate the applicability of the magnitude estimation procedure. To obtain individual stimulus‐response‐functions, butter of different temperatures was assessed sensorically for spread‐ability and hardness by means of a trained panel. Instrumental measurements were done with four empirical methods (apparent yield value; extruder; force penetration; sectility). Excellent exponential relationships were achieved between magnitude estimation and instrumental values. Due to individual responses, different constants in the power law equations were found. A second experiment showed that spreadability can be evaluated best by apparent yield value, whereas sensory hardness is imitated by sectility testing.
A RESEARCH NOTE UNIAXIAL COMPRESSION OF DOUBLE LAYERS OF SOLID FOODS 1
Authors: ROY ISABELLE , CAMPANELLA O. H. , NORMAND M. D. , PELEG M.
Published: February 2007

The compressive force deformation relationships of various foods, that included breads, cheeses and sausages, were described by a two parameter power model.

To predict the behavior of double layered arrays of some foods, their model parameters were incorporated into an equation that describes the relationships between the force and the total deformation of the array for a given cross‐sectional area and any initial thickness of each of the two layers. Construction of the force‐deformation relationships of the double layered array was done by numerical solution of this equation for various levels of deformation. The force deformation relationships predicted in this way were found to be in good agreement with experimental relationships. This was irrespective of whether the force deformation curve of the components had a concave upward or downward shape.
STRESS RELAXATION KINETICS OF MEAT BATTERS CONTAINING VARIOUS FILLERS DURING SMOKEHOUSE COOKING
Authors: CORREIA L. R. , MITTAL G. S.
Published: February 2007

Changes in stress relaxation properties during smokehouse cooking of meat batters containing various fillers were determined. The fillers used were butter‐milk powder, corn starch, modified corn starch, modified wheat flour, soy‐protein concentrate, whey‐protein concentrate, and micro‐crystalline cellulose. The cooking process was modelled using reaction kinetics and Eyring's absolute reaction rate theory. Enthalpy and entropy changes of activation were calculated for various properties and fillers.
THE COMPUTATION OF VISCOSITY AND RELAXATION TIME OF DOUGHS FROM BIAXIAL EXTENSION DATA 1
Authors: BAGLEY E. B. , CHRISTIANSON D. D. , TREBACZ D. L.
Published: February 2007

Stress (T) versus time (t) data were obtained for wheat flour doughs in lubricated, constant crosshead speed, uniaxial compression experiments. These data were then analyzed by using the Upper Convected Maxwell (UCM) Model with two parameters, a relaxation time (Λ) and a shear viscosity (η). The numerical solutions to the differential equation governing the behavior of the UCM model in this experiment can be very sensitive to the initial slope of the stress/time plots. This region of the curve, near t = 0, is most sensitive to experimental error. Best‐fit values of Λ and η were thus computed for a given curve at a series of initial starting points, ti, which were sequentially taken up the stress/time plots. There was considerable fluctuation in the best‐fit parameters but, nevertheless, values of relaxation time and shear viscosity could be obtained that gave good agreement between computed and experimental stress/strain curves.
EVALUATING SHEAR RATES FOR POWER LAW FLUIDS IN MIXER VISCOMETRY
Authors: CASTELL‐PEREZ M. ELENA , STEFFE JAMES F.
Published: February 2007

Established mixer viscometry methods, the viscosity matching and the slope methods, were evaluated for determining average shear rates when agitating time‐independent, non‐Newtonian fluids. Results indicate that the use of a constant value of the mixer proportionally constant, k', is not valid for all ranges of fluid rheological properties, system geometry (impeller and cup) and impeller rotational speed. A small impeller‐to‐cup diameter ratio and impeller rotational speeds greater than .33 rev/s (20 rpm) provide the optimum operating parameters for evaluation of k'.
EFFECTS OF VISCOSITY OF LIQUID FOODS ON PALATAL PRESSURE
Authors: TAKAHASHI JUNKO , NAKAZAWA FUMIKO
Published: February 2007

The deglutition of non‐Newtonian liquids introduced into the mouth was studied dynamically by measuring palatal pressure (P) with pressure transducers set at three locations on the palate. The value of P and the swallowing pressure (S) changed only from 100 to 200 g/cm2 over the viscosity range 10−2 to 101 Pa.s. The retaining time (T) and work (W), required for swallowing after the liquid entered the mouth, remained almost constant up to a critical value of 1.0 Pa.s. above which both T and W increased markedly. When the viscosity was low, all of the liquid was swallowed in one deglutition, up to 15 mL volume. Therefore, T was almost constant but S increased with the volume. When the viscosity was high, the liquid was swallowed in several smaller portions. When the volume was high, T increased and S was either constant or it decreased.
RHEOLOGICAL BEHAVIOR OF PROCESSED MUSTARD. II. STORAGE EFFECTS
Authors: AGUILAR C. , RIZVI S. S. H. , RAMIREZ J. F. , INDA A.
Published: February 2007

Samples of processed yellow mustard with three different particle size distributions (slightly‐coarse, standard, and fine) were prepared according to a standard formulation and pilot‐plant replication of the commercial methodology and stored for 3 months at 5°C, 25°C, and 45°C. After 3‐month storage at 45°C, all samples showed visible liquid separation (syneresis) and aggregation of colloidal particles, as indicated by increase in dpop and decrease in % colloids. The fine milled samples exhibited syneresis and an increase in dpop after 3‐month storage even at 25°C. The bimodal distribution did not show significant changes as a result of aggregation. In general, increase in dpop increased apparent viscosity (ηap), flow behavior index (n) from the Herschel‐Bulkley model, and exponent n″ from the loss modulus (G″) power law equation. As dpop increased, Bingham yield stress s̀o), plastic apparent viscosity (ηp), shear stress constant (A) from the Weltman stress decay model, yield stress (s̀o) and consistency index (m) from the Herschel‐Bulkley model, exponent n’ from the storage modulus (G') power law equation, and minimum values of loss tangent (tan δ) decreased. In heterodisperse semi‐solid foods such as processed mustard, the particle size distribution influences the structure (i.e., packing) and the rheological behavior. Therefore, time and temperature dependent instabilities such as syneresis may be minimized by controlling particle size distribution during processing.
SIMPLE DETERMINATION OF POWER LAW FLOW CURVES USING A PADDLE TYPE MIXER VISCOMETER
Authors: CASTELL‐PEREZ M. ELENA , STEFFE JAMES F. , MOREIRA ROSANA G.
Published: February 2007

A simple and accurate procedure to determine the flow properties of powerlaw fluids using a paddle type mixer viscometer is described. The approach considers the mixer as analogous to a concentric cylinder system and incorporates the inclusion of end effects in modeling. The procedure significantly reduces data collection because calibration with standard fluids is not necessary to estimate average shear stress and shear rate values.
SPEECH ANALYSIS TECHNIQUES: A POTENTIAL MODEL FOR THE STUDY OF MASTICATION SOUNDS
Authors: BROCHETTI DENISE , PENFIELD MARJORIE P. , BURCHFIELD SAMUEL B.
Published: February 2007

Acoustical characteristics of mastication sounds may provide information regarding the texture of food: however, methods are needed to study these sounds. Spectrographic analysis, a speech analysis technique, is a potential method for the study of mastication sounds. To illustrate this technique, spectrograms and waveforms are presented for sounds of foods that are reference standards for the hardness and fracturability scales of the Texture Profile Method. Spectrograms also are presented for the sounds of 3 vowels. Acoustical characteristics of these 2 types of sounds are described and compared from the spectrograms and waveforms.
OBJECTIVE MEASUREMENT OF THE STRETCHABILITY OF MOZZARELLA CHEESE
Authors: CAVELLA S. , CHEMIN S. , MASI P.
Published: February 2007

Despite the great attention that has been devoted to cheese rheology to date no rheological analyses to characterize cheese stretchability by well‐defined physical terms has been proposed. This paper illustrates the possibility of using a test commonly used to characterize polymer melt response to spinning to objectively measure cheese stretchability. The behaviour of cow milk Mozzarella cheese with varying temperature is presented. The results show that there exists a well‐defined temperature range in which the cheese can be stretched, and that within this range there is a temperature at which the cheese stretchability reaches its maximum value.
RHEOLOGICAL BEHAVIOUR OF BUTTER AT LARGE DEFORMATIONS
Authors: ROHM H.
Published: February 2007

Eleven traditionally produced butter samples were evaluated for rheological properties at large deformations by lubricated and nonlubricated uniaxial compression with varying sample geometries and compression rates, by stress relaxation in shear and creep experiments in compression at 5–20C each. Compression forces required to deform cylindrical samples in nonlubricated conditions were higher than in lubricated cases. Correction of shape changes in nonlubricated stress‐strain curves resulted in good agreement with lubricated experiments at low compression rates up to stress maxima or yielding. As frictional forces were relatively smaller at high deformation rates, lower stresses were obtained in nonlubricated conditions. Samples with higher height/diameter ratios showed more pronounced stress maxima. A biaxial extensional viscosity, ηbe, was computed for nonbrittle, soft samples. Typical slopes in logarithmic plots of viscosity against strain rate were approximately ‐1. At strains of about 0.01 creep compliance depended on compression stress. The average ratios of recovered to initial instantaneous compliance were between 0.31 and 0.59, and increased with sample temperature. A calculated ηBE from creep compression showed fair agreement with ηBE from static compression experiments. At comparable strains, a conversion of creep compliance to the stress relaxation modulus by an approximate method showed a good fit of experimental results.
JAW MOVEMENT DURING MASTICATION OF FIBROUS AND NONFIBROUS COMPOSITE FOODS BY ADULT SUBJECTS
Authors: LANGLEY KEITH R. , MARSHALL RICHARD J.
Published: February 2007

A cinematographic study was made of subjects during mastication of fibrous and nonfibrous foods. The motion of the jaw was analysed mathematically. Each cycle of the vertical movement of the jaw could be considered as a combination of a sinusoidal motion, chewing phase, and a linear one, jaw opening phase. The lateral movement was not so well defined. On average, females took longer to chew foods and had smaller jaw movements than males. Fibrous foods took longer to chew and the amplitudes were larger than nonfibrous foods. The maximum rate of jaw movement during chewing ranged from 15 mm s−1 to 30 mm s−1, with males chewing at faster rates than females.
A COMPARISON OF THE VISCOELASTIC PROPERTIES OF CONVENTIONAL AND MAILLARD PROTEIN GELS
Authors: ARMSTRONG HELEN J. , HILL SANDRA E. , SCHROOYEN PETER , MITCHELL JOHN R.
Published: February 2007

The properties of gels prepared by heating solutions of bovine serum albumin (BSA) for 30 min at 121C in the presence and absence of glucono‐delta‐lactone (GDL gels) and xylose (Maillard gels) were compared. During formation the pH of the Maillard and GDL gels decreased to 4.9 whereas the pH of the gels formed in the absence of GDL or xylose remained near neutral. Maillard gels show much less syneresis compared with the GDL gels and contained nondisulphide covalent crosslinks as evidenced by very low protein solubilities in mixtures of sodium dodecyl sulphate and β‐mercaptoethanol. Both the GDL and Maillard gels could be formed at much lower protein concentrations than the neutral conventional gels. The stress relaxation of the gels in compression was measured and the response analyzed using Peleg's equation. The parameters in this equation were not strongly dependent on protein concentration or degree of deformation. The neutral pH gels were far more elastic than the low pH gels, but despite the difference in crosslinking mechanisms the viscoelastic behaviour of the Maillard and GDL gels was similar. However, the break strength and asymptotic residual modulus of the Maillard gels were higher. It is suggested that the stress relaxation occurs in weaker, noncovalently linked regions of the gel, whereas the nondisulphide covalent crosslinks in the Maillard gels reinforce strong regions already containing disulphide linkages.
EFFECT OF SAMPLE VOLUME ON THE COMPRESSIVE FORCE‐DEFORMATION CURVES OF CORN FLAKES TESTED IN BULK1
Authors: NIXON RICHARD , PELEG MICHA
Published: February 2007

Two national brands of cornflakes were compressed in cells of various dimensions (height 38–76 mm and diameter 50–91 mm) using a Universal Testing Machine. The stress‐strain (σ vs. ε) relationships could be described by a four parameter model originally developed for cellular materials, i. e., σ(ε) = k1εn1+ k2εn2 where the k's and n's are constants (n1 < 1, n2 > 1). The scatter around the fitted relationships was normalized and its jaggedness determined in terms of an apparent fractal dimension and the mean magnitude of the power spectrum after filtering. The magnitude of both depended on the cell diameter and height indicating that the observed degree of jaggedness is influenced simultaneously by “averaging” and “cushioning” effects.
SENSORY TEXTURE PROFILE, GRAIN PHYSICO‐CHEMICAL CHARACTERISTICS AND INSTRUMENTAL MEASUREMENTS OF COOKED RICE
Authors: ROUSSET SYLVIE , PONS BRIGITTE , PILANDON CARINE
Published: February 2007

Three samples of raw‐milled rice, and 4 differently parboiled rices were used to study and to relate sensory perception to instrumental measurements. Variance analysis showed that some physico‐chemical characteristics indicated great differences among rice samples: thickness of cooked grain, length/width ratio, water uptake, elastic recovery, white core rate and amylose and protein contents. The most discerning sensory attributes were: elasticity, stickiness, pastiness, mealiness, length of grain, firmness, crunchiness, time in mouth, brittle texture and juiciness. The correlation circle of the principal component analysis (PCA) showed high correlation between some sensory characteristics and instrumental measurements. Melting texture, surface moistness, juiciness, were positively correlated with water uptake (r = 0.70, 0.61, 0.71). Granular texture, crunchiness, brittleness and mealiness were significantly affected by white core presence (r = 0.81, 0.74, 0.86, 0.83). Elasticity was dependent upon elastic recovery and firmness measured by the Viscoelastograph, but not linearly. Length of cooked grain was correlated with the length/width ratio of raw grain (r = 0.83). Pastiness, compactness, stickiness were slightly influenced by the thickness of raw grain (r = 0.81, 0.67, 0.72). To a weaker extent, the sensory firmness was associated with the firmness measured by extrusion force using an Ottawa cell (r = 0.58). PCA showed greatdifferences in texture between rices. Two of the parboiled rices were very elastic, another was firm, granular, crunchy and mealy. The remaining two, cooked longer, were moister and more melting. Among the 3 samples of raw‐milled rices, differences in grain length feeling and melting‐granular‐brittle characteristics. were distinguished.
RHEOLOGICAL BEHAVIOUR OF KIWI FRUIT JUICE CONCENTRATES
Authors: IBARZ A. , GINER J. , PAGAN J. , GIMENO V. , GARZA S.
Published: February 2007

The rheological behaviour of diluted kiwi concentrates (22.5–63.0 °Brix) over the temperature range 4 to 70C, was studied. The values below 55.7 °Brix fit the power law while above 55.7 °Brix fit the Herschel‐Bulkley equation. Maximum and minimum consistency index values were 62225 and 16 mPa. sn. Concentrates showed a yield stress at 55.7 °Brix, from 5 to 11 Pa, and 63.0 °Brix, from 19 to 53 Pa. Yield stress was correlated with temperature by means of a linear equation. Arrhenius activation energies were in the range of 28.97 to 33.89 kJ/mol. The average value of the flow behaviour indexes varied from 0.85 (sample at 22.5 °Brix) to 0.59 (sample at 63.0 °Brix). Simple equations are proposed to describe the combined effect of temperature and soluble solids content on consistency index and rheological behaviour index.
ASSESSMENT OF A PIN DEFORMATION TEST FOR MEASUREMENT OF MECHANICAL PROPERTIES OF BREAKFAST CEREAL FLAKES
Authors: GEORGET D. M. R. , PARKER R. , SMITH A. C.
Published: February 2007

A pin deformation test is assessed for the measurement of the mechanical properties of breakfast cereal flakes where well‐defined procedures like the three point bend test are not easily carried out. These properties are compared with the literature on formed specimens of cereal components, starch polymers and proteins. A classical analysis of a centrally loaded disc on a circular support was used to obtain the Young's modulus, the maximum stress and the maximum strain from the force‐displacement curve. The technique was validated for synthetic polymer discs of known modulus. The Young's modulus for formed discs of starch and gluten as a function of water content agreed reasonably well with independent results using a three point bend test. Formed discs of ground flake showed a similar response to that of gluten. The technique was then applied to individual flakes which were flattened by a hydration‐dehydration procedure and conditioned to different water contents. The stiffness and stress at failure decreased with increasing water content as reported for gluten but their magnitudes were lower, which was attributed to the greater porosity relative to pressed specimens. Some unflattened and low water content flakes were also tested and (although not conforming to the planar geometry of the analysis) showed similarity in stiffness (although not in strength) with their flattened counterparts.
KINETIC OF SOFTENING OF CARROT BY GAMMA RADIATION
Authors: BOURNE MALCOLM C.
Published: February 2007

Raw carrots were diced into 9.5 mm cubes, and subjected to gamma radiation between an array of Co60 pencils. A series of doses ranging from 0 to approximately 50 kGy was given. A plot of log (extrusion force) versus dose showed two distinct regions; the first is a rectilinear plot with a steep negative slope for doses up to about 15 kGy. The second is also a rectilinear plot with a shallow negative slope beyond 15 kGy. Sixty‐seven percent of the firmness is lost with the first 15 kGy but only 4% of the firmness is lost with the highest 15 kGy increase in dose. This two‐stage softening rate curve is consistent with the model of two first‐order kinetic rate processes and is qualitatively similar to that for thermal softening of carrot. The term “radiation firmness” is proposed to describe the amount of firmness that is resistant to degradation by irradiation.
OSCILLATORY RHEOMETRY: THE NECESSITY FOR SAMPLE TEMPERATURE CORRECTION1
Authors: PETROFSKY E.A. , HOSENEY R.C.
Published: February 2007

Preliminary results using an oscillatory probe rheometer to follow sol to gel transformations of pasted starch gave illogical results. G″ appeared to increase instead of decrease, as would be expected for a gelling sol. The increase was dramatic at high temperatures. In many instances the viscosity loss values (η') were negative, which is physically impossible. Therefore, the equations used were examined for a source of error. It was found that no temperature correction was made for probe frequency in the test sample. Use of the temperature correction for probe frequency in the sample along with the equations provided with the instrument showed that the oscillatory probe rheometer effectively measured viscous and viscoelastic properties of starch gel systems throughout the sol to gel transformation.
EFFECTS OF HYDROCOLLOIDS AND ASPARTAME ON SENSORY VISCOSITY AND SWEETNESS OF LOW CALORIE PEACH NECTARS
Authors: PASTOR M.V. , COSTELL E. , DURÁN L.
Published: February 2007

Effects were studied of interactions between each of three hydrocolloids‐xanthan gum, guar gum and methylcellulose‐ and aspartame on sweetness intensity and sensory viscosity of low‐calorie peach nectars (60% fruit purée with no sucrose added). The flows of the nectars were characterized as near Newtonian without hydrocolloids, as Bingham plastic at lower hydrocolloids concentrations and as pseudoplastic at higher concentrations (Ostwald flow for guar and methylcellulose, and Herschel‐Bulkley for xanthan). Hydrocolloids concentrations were selected to cover viscosity range of commercial whole nectars: 0.10 and 0.20% xanthan or guar, and 0.15 and 0.30% methylcellulose. Aspartame concentrations tested were derived from the calculation of equisweet concentration as referred to a control nectar sample with sucrose (14°Brix) and of the upper and lower limen value: 0.216, 0.360 (equisweet), 0.502, and 0.644 g/L. Addition of either guar or methylcellulose did not alter the perceived sweetness in aspartame‐sweetened peach nectars. Xanthan addition, even at 0.10%, significantly lowered sweetness of samples sweetened with the highest aspartame concentration (0.644 g/L). Addition of aspartame did not modify the perceived viscosity in samples thickened with either xanthan or guar gums. At all methylcellulose concentrations tested, samples with the lowest aspartame concentration (0.216 g/L) were perceived as less viscous.
EVALUATION OF THE RHEOLOGICAL PROPERTIES OF FRESH CORN MASA USING SQUEEZING FLOW VISCOMETRY: BIAXIAL EXTENSIONAL VISCOSITY1
Authors: RAMÍREZ‐WONG B. , SWEAT V.E. , TORRES P.I. , ROONEY L.W.
Published: February 2007

Alkaline corn was cooked for 20, 55 or 80 min, and the nixtamal was ground into masas with medium or coarse particle size distributions. Water was added to each corn masas in order to obtain the same adhesiveness. Rheological properties of these masas were evaluated with the squeezing flow viscometry technique with lubrication at crosshead speeds of 0.05, 0.2 and 0.5 cm/min, respectively. From the data collected, stress‐strain and biaxial elongational viscosityradial extension rate curves were obtained. All the fresh corn masas gave the same stress and elongational viscosity at any given specific strain and radial extension rate, respectively, regardless of the cooking time and degree of grinding. The elongational viscosity could be useful to predict fresh corn masa behavior during molding and cutting steps in the tortilla‐making process.
KINETIC MODELING OF VEGETABLE COOKING AT 100C
Authors: RAMESH M.N. , SATHYANARAYANA K. , GIRISH A.B.
Published: February 2007

Kinetics of cooking of green peas, carrot, radish and knolkol were determined from the compression force ratio of the vegetables before and after cooking. The kinetics of rice and potato cooking, both starchy products were found to be suitable in explaining the kinetics of cooking of vegetables. The degree of cooking was correlated to cooking time and the reaction rate constant, K, value was determined for four vegetables. With this K value the degree of cooking at various other cooking times was predicted. The R2 value and standard error of estimate were determined.
FINITE ELEMENT ANALYSIS OF MODES OF VIBRATION IN APPLES
Authors: LU RENFU , ABBOTT JUDITH A.
Published: February 2007

Three‐dimensional finite element models were developed to study modes of vibration in apples. The apple models were created using two mathematical equations, in which the geometry of the apple was described by a four‐parameter equation and the core structure by an exponential function. Modal analyses were performed to identify the vibrational modes and to study the effects of material properties, structure (i.e., the skin and core), shape, and size on them. There were three classes of vibrational modes in apples: torsional, spheroidal, and nonaxisymmetric. A majority of modes between 0 and 2000 Hz belonged to the nonaxisymmetric class. The square of natural frequency was linearly related to Young's modulus of the apple. The presence of apple skin could increase the natural frequency by 7% for torsional modes and less than 4% for spheroidal modes. As the elastic modulus of the core was doubled, the natural frequency increased by up to 7% for spheroidal modes and well below 1% for torsional modes. The natural frequency for the first mode of each class decreased by no more than 8% as Poisson's ratio was doubled. Apple shape had a large effect on the natural frequencies of all three mode classes; spheroidal modes, however, were less affected by apple shape. The natural frequencies decreased with increasing apple size, but use of the firmness index f2m2/3, where f is the natural frequency and m is the mass of the apple, minimized the size effect.
RHEOLOGICAL AND CALORIMETRIC PROPERTIES OF HEATED CORN STARCH‐SOYBEAN PROTEIN ISOLATE DISPERSIONS
Authors: LIAO H‐J. , OKECHUKWU P.E. , DAMODARAN S. , RAO M.A.
Published: February 2007

Differential scanning calorimetric (DSC) data on 10% (w/w) corn starch dispersion showed one endothermic peak and on soybean protein (SP) isolate dispersions two peaks attributed to 7S and 11S globulins. In corn starch‐SP isolate mixtures, thermal transitions appear to occur independently of one another. Dynamic rheological data over 0.63–62.9 rad s‐1 revealed weak gel‐like behavior of both 10% corn starch and SP isolate dispersions with magnitudes of storage modulus (G′) being significantly higher than those of loss modulus (G″) and both exhibiting slight frequency‐dependence; G′ of corn starch dispersion was higher than that of SP isolate and in mixed dispersions its magnitude decreased with increase in proportion of protein. The Maxwell model described creep‐compliance data on dispersions high in corn starch, while the Burgers model described dispersions high in SP isolate. Plots of protein/starch ratio versus G′ and instantaneous elastic modulus showed similar trends in phase separation and inversion.
RHEOLOGICAL PROPERTIES OF HEATED CORN STARCH + SOYBEAN 7S AND 11S GLOBULIN DISPERSIONS
Authors: CHEN C‐J. , LIAO H‐J. , OKECHUKWU P.E. , DAMODARAN S. , RAO M.A.
Published: February 2007

At 10% solids content, magnitudes of G′ and G″ of soybean 7S dispersion were substantially lower than those of corn starch dispersion, while those of soybean 11S dispersion were much higher than those of starch. Profiles of G′ at 30 Hz as a function of starch concentration of starch + 7S and starch + 11S gels were asymmetrical reflecting phase separation due to thermodynamic incompatibility. However, the starch concentration corresponding to the critical point below which no phase separation occurs for the starch + 7S dispersion was about 7% and for the starch + 11S dispersion it was about 3%. At equal starch fractions, values of G′ at 30 rad s‐1 of corn starch + 7S dispersions were nearly equal to those of only corn starch. In contrast, at starch concentrations between 6–8%, G′ values of the corn starch + 11S dispersions were much higher than those of only starch and a minimum value occurred at a starch concentration of about 5%. Based on frequency dependence of G′ values, heated corn starch + 7S dispersions may be classified as weak gels, while heated corn starch + 11S dispersions may be classified as true gels.
GLASS TRANSITION AND TEXTURE IN A TYPICAL SPANISH CONFECTIONERY PRODUCT: XIXONA TURRON
Authors: MARTINEZ NURIA , CHIRALT AMPARO
Published: February 2007

The water sorption isotherm at 25C and glass transition temperature were determined in a typical Spanish confectionery product (Xixona turrón), as well as in the fat‐free product. The samples were equilibrated at water activity levels from 0.113 to 0.755. The GAB and BET models were fitted to sorption data and the monolayer moisture contents were 2.8 and 6.0 (g of water/100 g of dried sample) for turrón and fat‐free turrón, respectively. The sorption data indicate a lipid interaction with hydrophilic constituents. The analysis of the glass transition temperature (Tg) of the product as a function of its moisture content is used to determine the critical water content (CWC) at which the product becomes rubbery, at a determined temperature. From sorption isotherm at the same temperature (25C) we can also determine the critical water activity (CWA). The plasticizing effect of water in Xixona turrón can be modeled by the Gordon and Taylor equation. The fat also has a plasticizing effect, which is more obvious at low water content. A Texture Profile Analysis (TPA) was performed on samples with different moisture contents. Only samples with a moisture content lower than CWC showed fracturability, due to its glassy state. In the rubbery state hardness, gumminess and chewiness decrease when water content increases. Elasticity and cohesiveness increase in line with water content, more strongly for those moisture levels which are higher than BET monolayer value.
CONSTANT STRAIN RATE COMPRESSION OF BIOPOLYMER GELS
Authors: ROHM H. , JAROS DORIS , BENEDIKT JULIA
Published: February 2007

Usually, uniaxial compression of food materials is performed at constant speed, which causes an increase of the true strain rate during experiments. By using a method described previously (Jaros and Rohm 1994) highly elastic biopolymer gels were compressed at standard conditions and with decreasing crosshead speed in order to maintain constant strain rate conditions during test. In the case of gels showing failure at a Hencky deformation of > 0.5‐0.6, significantly lower values for apparent fracture strain were found in constant strain rate compression. Differences in stress at apparent fracture showed good agreement with respect to this critical value. Implications and consequences on interrelation between sensory and instrumental measurements as well as on relationships between rheological and fracture properties are discussed.
EFFECTS OF OIL DROPLETS ON PHYSICAL AND SENSORY PROPERTIES OF O/W EMULSION AGAR GEL
Authors: KIM KYUNG‐HEE , GOHTANI SHOICHI , YAMANO YOSHIMASA
Published: February 2007

Effects of oil droplets in an agar gel matrix were investigated by mechanical analyses and sensory evaluation. The results for compressive and puncture properties were expressed in terms of relative values. All compressive properties; stress, strain and compressive energy of emulsion gels, as obtained by compression tests, decreased with both increases of oil droplet size and oil volume fraction. The stress, strain and energy of the emulsion gels obtained by puncture tests did not change with an increase in oil droplet size. Results of sensory evaluation showed that the sample containing small oil droplets was harder than that with large oil droplets. On the other hand, the large oil droplet sample was oilier than that with small oil droplets. The sensory evaluations for hardness and oiliness of emulsion gels did not exhibit significant relations to most of the properties of mechanical analyses.
MICROSTRUCTURAL CHARACTERISTICS AND COMPRESSION RESISTANCE AS INDICES OF SENSORY TEXTURE IN A CRUNCHY SNACK PRODUCT
Authors: GURAYA H.S. , TOLEDO R.T.
Published: February 2007

Identically formulated drum dried and cold formed half‐products were puffed in hot air or by frying to determine microstructure‐texture relationships. Structural attributes measured were cell size (CS), number of cells per unit area (CN), cell wall thickness (CW) and product specific volume (SV). Sensory attributes of crunchiness, hardness and density were also evaluated. Puffed product microstructure depended more on the half‐product preparation process than the method of puffing. Similarly prepared half products had the same microstructural attributes whether fried or hot air puffed. Sensory scores for crunchiness were not significantly different among all samples but scores for hardness and density were significantly different between hot air puffed and fried products even when microstructural attributes were similar. Higher compression force values reflected lower sensory scores for crunchiness and hardness of puffed products. Compression force was significantly correlated with microstructural attributes of CS, CW and SV.
UNIAXIAL COMPRESSION OF UF‐FETA CHEESE RELATED TO SENSORY TEXTURE ANALYSIS
Authors: WIUM H. , QVIST K.B. , GROSS M.
Published: February 2007

Rheological characteristics of seven Feta cheeses with different textures and produced from ultrafiltered milk (UF‐Feta cheeses) were evaluated by uniaxial compression and sensory texture analysis. The effect of uniaxial deformation rate (50–2500 mm/min) on four rheological parameters: Stress at fracture s̀f), Hencky strain at fracture (ɛf), deformability modulus (E) and work to fracture (Wf) was examined. Three Principal Components (PC) described 76, 16 and 4% respectively, of the variation in the uniaxial compression data set (4 parameters at 12 deformation rates). Statistically αf, E and Wf described the same type of information in the data set. Six sensory texture attributes of the UF‐Feta cheeses were evaluated by a sensory texture panel: nonoral firmness, nonoral brittleness, nonoral spreadability, oral crumbliness, oral firmness and oral stickiness. One PC described 93% of the variation in the sensory texture data and grouped the sensory variables into two negatively correlated groups: nonoral firmness nonoral brittleness, oral firmness and oral crumbliness versus nonoral spreadability and oral stickiness. Correlations and Partial Least Squares regression (PLS) between instrumental and sensory texture variables showed that nonoral and oral firmness were the nonoral and oral sensory variables best predicted from instrumental measurements. αf, E and Wf were all able to predict nonoral and oral firmness. Of the instrumental parameters, αf generally gave the best correlation to nonoral firmness at all deformation rates. Above a deformation rate of 50 mm/min correlations between αf and nonoral firmness were almost independent of deformation rate, and at any deformation rate correlations between αf and oral firmness
USING BROOKFIELD DATA AND THE MITSCHKA METHOD TO EVALUATE POWER LAW FOODS
Authors: BRIGGS JENNI L. , STEFFE JAMES F.
Published: February 2007

Mitschka proposed a simple technique to calculate average shear stress and average shear rate from data obtained with Brookfield viscometers. It allows for estimation of the apparent viscosity, the flow behavior index, and the consistency coefficient of power law fluids. This method was evaluated for typical shearthinning foods (banana puree, salad dressing, enchilada sauce, and pancake syrup) and found to have excellent potential for quality control testing in the food industry. Results compared favorably with those obtained with a standard cone and plate viscometer.
IMPERFECT SQUEEZING FLOW VISCOSIMETRY OF SELECTED TOMATO PRODUCTS1
Authors: LORENZO M. ALEJANDRA , GERHARDS CHRISTIAN , PELEG MICHA
Published: February 2007

The rheological properties of different brands of commercial tomato paste, sauce, puree and ketchup were estimated by imperfect squeezing flow viscosimetry using a wide plate and a shallow container. The tests were performed with polished and grooved surfaces. In both, slip was prominent to such an extent that the equations for lubricated squeezing flow had to be used for the calculation of rheological parameters. Despite its crudeness, the procedure was sensitive enough to consistently monitor rheological differences between commercial products of different brands in terms of the apparent stress at a given specimen height, the consistency, K, and flow index, n, of the pseudoplastic liquid constitutive equation, and the apparent biaxial elongational viscosity, μb and its strain rate dependency. In tomato paste, the flow behavior index was approximately the same in all the brands (n ∼ 0.5), and the values of K and μb had a linear relationship. Residual forces after relaxation provided an additional textural measure related to the yield stress. Differences between products of different brands could be consistently monitored regardless of whether the test was performed at a fixed specimen height or a preset initial force.
USE OF FAT BLENDS IN CHEESE ANALOGS: INFLUENCE ON SENSORY AND INSTRUMENTAL TEXTURAL CHARACTERISTICS
Authors: LOBATO‐CALLEROS C. , VERNON‐CARTER E.J. , GUERRERO‐LEGARRETA I. , SORIANO‐SANTOS J. , ESCALONA‐BEUNDIA H.
Published: February 2007

Cheese analogs were prepared with the fat fraction composed of butterfat, soybean fat or soybean oil and their blends, in accordance with an experimental design of three components. The ten resulting formulations were subjected to a texture profile instrumental analysis and sensory analysis by a quantitative ranking test. Principal Component Analysis showed that the instrumental textural characteristics of hardness and adhesiveness were negatively correlated to cohesiveness and springiness, while the sensory texture characteristic of firmness was correlated negatively with elasticity and creaminess. Soybean fat confers hardness and adhesiveness to the cheese analogs, but decreases their cohesiveness and springiness, while the opposite effect is due to soybean oil and butterfat.
FLOW BEHAVIOR OF CONCENTRATED STARCH DISPERSIONS USING A TUBE RHEOMETER OF NOVEL DESIGN
Authors: XU ZHENMIAO , RAPHAELIDES STYLIANOS N.
Published: February 2007

A tube rheometer of novel design was used to study the flow properties of starch dispersions with concentration from 7 to 30% w/w at 95C. The flow properties of maize starch dispersions were largely influenced by the time of cooking and shearing that elapsed before the measurements were taken. Viscosity gradually decreased with the time of shearing until it reached a minimum value which then remained constant. Viscosity measurements, taken at 95C and 75C, of dispersions of 10 and 15% w/w starch concentration indicated that the activation energy of the flow was concentration dependent. The flow behavior shown by the starch dispersions was attributed to the presence of the amylose matrix rather than to swollen granules.
FRACTAL DETERMINATION OF CRISP OR CRACKLY TEXTURES
Authors: NORTON CLIVE R.T. , MITCHELL JOHN R. , BLANSHARD JOHN M.V.
Published: February 2007

This paper demonstrates a different and novel approach to fractal analysis of multi‐peak curves obtained on compression of expanded extruded rice with a range of water contents. The importance of high resolution measurements (down to 5 μm) and the correlation with a sensory panel's perception of different textures is shown. Sensorial textures were correlated with differences in measured line lengths as spatial resolutions (from 10.240 to 0.005 mm) were doubled during analysis by a simple compression test. Crispness and crackliness perceived by a sensory panel correlated with differences between different consecutive pairs of line lengths. This showed how mechanical testing can be used to evaluate crispness and crackliness of samples.
BOOK REVIEWS
Authors: PATERSON JANET
Published: February 2007

CHEMICAL AND FUNCTIONAL PROPERTIES OF FOOD COMPONENTS.
EFFECTS OF OIL DROPLET AND AGAR CONCENTRATION ON GEL STRENGTH AND MICROSTRUCTURE OF O/W EMULSION GEL
Authors: KIM KYUNG‐HEE , GOHTANI SHOICHI , MATSUNO RYUICHI , YAMANO YOSHIMASA
Published: February 2007

The effects of oil droplet size and agar concentration on gel strength and microstructure of emulsion gels were investigated by compression test and cryoscanning electron microscope (Cryo‐SEM). At all agar concentrations, the compressive stress values of emulsion gels were lower than those of the oil‐free gels. Compressive stress and energy were significantly affected by oil droplet size and agar concentration, but compressive strain was not. SEM observation revealed that the overall volume of void spaces decreased and strand compactness increased with increasing agar concentration. Gels containing oil droplets had some void spaces between the gel network and the oil droplets. The strands of emulsion gels did not cover the oil globules completely, a phenomenon which was also observed for the gel with high agar concentration.
INFLUENCE OF PARBOILING ON RICE STARCH STRUCTURE AND COOKED‐RICE TEXTURE
Authors: RAMESH M. , ALI S. ZAKIUDDIN , BHATTACHARYA K.R.
Published: February 2007

Four varieties of rice having very high (29.4%) to low (17.6%) amylose‐equivalent (AE) were parboiled by steaming at atmospheric (PB‐O) and at 3 kg/cm2 (PB‐3) gauge pressure. The cooked rice texture of the raw, PB‐0 and PB‐3 rice was determined by Viscoelastographe. Gel permeation chromatography of rice flour starch on Sepharose CL‐2B, in general, indicated thermal breakdown of starch. The extent of starch breakdown and the firmness values of cooked PB‐0 and PB‐3 rices were reasonably well correlated suggesting that starch breakdown during parboiling may have some role to play in varying the texture of rice by parboiling. The chain profile of rice starch remained unaltered after parboiling.
ACOUSTIC WAVE ANALYSIS FOR FOOD CRISPNESS EVALUATION
Authors: LIU XIAOQIU , TAN JINGLU
Published: February 2007

Sound signals for five snack food products at two moisture levels were recorded digitally and product crispness was evaluated by a trained sensory panel. Sound signal features were extracted by analyzing signal‐value and power‐value dependencies. Principal component regression and neural network techniques were used to determine the usefulness of the sound signal features as predictors of sensory crispness. In a validation test, a trained neural network model predicted sensory crispness from sound signal features to an R2‐value of 0.89. The results show the effectiveness of the techniques employed to extract and use sound signal features for crispness evaluation.
RHEOLOGY AND MICROSTRUCTURE OF WHEAT DOUGH DEVELOPED WITH CONTROLLED DEFORMATION
Authors: SCHLUENTZ EMILY J. , STEFFE JAMES F. , NG PERRY K.W.
Published: February 2007

Undeveloped wheat dough samples were strained in shear and extensional flow between parallel plates to produce a controlled level of development. Dough made in a standard Farinograph, considered developed dough, was used for comparison. Scanning electron microscopy images of deformed dough were subjected to numerical image processing to characterize the protein matrix present. Results were compared to dynamic rheological properties to evaluate the influence of strain deformation on the formation of microstructure. Viscoelastic moduli of wheat dough showed that developed dough had the greatest amount of structure formation, followed by extensionally‐strained and shear‐strained samples, respectively. Undeveloped dough showed the lowest levels of structure development. Image analysis indicated statistically significant differences between protein matrices in developed and undeveloped samples; however, results were not significantly different between shear‐ and extension‐ally‐strained samples.
EFFECT OF INCORPORATION OF DEFATTED SOYFLOUR ON THE TEXTURE OF CHAPATIS
Authors: GANDHI A. P. , KOTWALIWALE N. , TAIMINI V. , KAWALKAR J. , SRIVASTAV D. C. , PARIHAR V. S. , NADH P. RAGHU
Published: February 2007

Incorporation of defatted soyflour in an all wheat flour for making chapatis has a significant effect on its nutritive profile and textural profile parameters. The protein content was increased from 11.9% to 19.8% at the 20% blending level. The textural parameters hardness, cohesiveness, springiness and chewiness were also affected by the addition of defatted soyflour both at zero and 24 h of storage. All the chapatis were acceptable when fresh but not after 24 h.
RHEOLOGY OF WHEAT DOUGHS FOR FRESH PASTA PRODUCTION: INFLUENCE OF SEMOLINA‐FLOUR BLENDS AND SALT CONTENT
Authors: PERESSINI DONATELLA , SENSIDONI ALESSANDRO , POLLINI CLAUDIO MARIA , DE CINDIO BRUNO
Published: February 2007

Dynamic measurements were made with a controlled stress rheometer to study the viscoelastic properties (G', G', δ) of wheat doughs (45% wb water content) for fresh pasta production prepared with different blends of durum wheat semolina and common wheat flour with different concentrations of sodium chloride. Increasing the semolina and sodium chloride content, increased the strength and the solid‐like behaviour of semolina‐flour blends. The physical properties of dough were strongly dependent on particle size distribution and salt addition. By manipulating semolina‐flour ratio and ionic strength, it was possible to obtain semolina‐flour doughs with a rheological behaviour close to that of pure semolina dough.