bluuebunny/crossref_metadata_2025 huggingface dataset:
DIFFERENTIATION OF MYOFIBRILLAR AND CONNECTIVE TISSUE STRENGTH IN BEEF MUSCLES BY WARNER‐BRATZLER SHEAR PARAMETERS
Authors: MOLLER A. J. , SORENSEN S. E. , LARSEN M.
Published: February 2007

Heat induced changes in aged bovine m. longissimus dorsi (LD) and m. biceps femoris (BF) were studied by water bath cooking to 60, 70 or 80°C at slow (.12°C/min) and fast (.6°C/min) heating rates. Forcedeformation curves from the Warner‐Bratzler (WB) shear device were used to evaluate specific changes in the myofibrillar (WB M‐force) and connective tissue component (WB C‐force) of tenderness. Other measurements include WB peak force value, cooking loss, collagen solubility and sensory evaluations. Differences due to muscle type were significant in all parameters except collagen solubility. Both WB M‐ and WB C‐force were reduced by slow heating rate but for samples heated to 80°C, WB M‐force was affected only by heating rate below 60°C while WB C‐force was most influenced above 60°C. Effect of final temperature resulted in higher WB M‐force from 60°C to 70°C, whereas WB C‐force was most affected from 70°C to 80°C. On the contrary, WB peak force was less affected by final temperature. Due to concomitant and opposing changes in myofibrillar and connective tissue strength with increasing end point temperature, it is concluded that improvements in interpretations with regard to heat‐induced changes and response of heat treatment in various muscles may be increased by measurement of WB M‐force and WB C‐force from shear force‐deformation curves.
CHARACTERIZATION OF STRUCTURE BREAKDOWN OF FOODS FROM THEIR FLOW PROPERTIES
Authors: FIGONI PAULA I. , SHOEMAKER CHARLES F.
Published: February 2007

Advances in the characterization of the complex time‐dependent flow properties of liquids and semisolids are reviewed, with special emphasis placed on recent developments in elucidating the behavior of food systems when sheared. Time dependency is discussed in terms of viscoelasticity and structural changes. Systems as diverse as mineral oils, lotions and creams, egg custards, and mayonnaise are shown to exhibit a similar stress decay over time when sheared at a constant rate. Various mathematical descriptions, both theoretical and empirical, are used to characterize the stress decay, which is due to structural changes (e.g. thixotropy) that occur within the system as it is sheared. Evidence is provided that the stress decay varies with product formulation and experimental conditions, such as temperature, shear rate, and viscometer gap width. A discussion of the uses and disadvantages of steady shear measurements is included.
SPINNING OF FABABEAN PROTEIN 1. FLOW PROPERTIES OF FABABEAN PROTEIN DOPES BY CAPILLARY EXTRUSION VISCOMETRY
Authors: CULIOLI J. , SALE P.
Published: February 2007

Flow properties of Fababean protein dopes were studied by capillary extrusion viscometry. The consistency of these dopes was time dependent for pH values between 11 and 13 and it increased slightly with time. At still higher pH values it decreased sharply after 1 h aging. For protein concentration between 11% and 15% (w/w), and pH 11–13.5, these dopes exhibited shear thinning behaviour in the shear rate range 500–20,000 s−1 and they followed the power law τ= cγn. This relationship could be written in the dimensionally homogeneous form:

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When the protein concentration of the dopes increased the power law index (n) decreased and the consistency index (C) increased. A maximum consistency was reached at pH 12.5 while the power law index was minimum.

The results can be explained in terms of protein‐protein interactions and of macromolecule denaturation.
SPINNING OF FABABEAN PROTEIN 2. SPINNABILITY OF DOPES AND TEXTURAL PROPERTIES OF PROTEIN FIBRES
Authors: CULIOLI J. , SALE P.
Published: February 2007

Experiments were carried out to determine the influence of the pH and the protein content of Fababean protein dopes on the spinning process and on the textural properties of resulting fibres. Spinning was only possible if the protein content of the dopes was over 10% and the pH over 11. It was only under 12% that the protein content affected the spinning and the fibre characteristics. The spinnability expressed in terms of maximum takeup velocity increased with pH until a maximum value was reached at pH 12.5 and over. The properties of the fibres were related to the pH of the corresponding dopes: the shear strength increased and the moisture content decreased when the pH varied from 11 to 13.5. Spinnability of protein dopes and textural characteristics of the fibres are very dependent on the denaturation of the macromolecules in the dopes which influences the chain‐chain interactions in the fibres.
SOME TENSILE CHARACTERISTICS OF RAW FISH FLESH1
Authors: SEGARS R. A. , JOHNSON E. A. , KAPSALIS J.G. , PELEG M.
Published: February 2007

The rheological characteristics of fresh fish fillets were studied by an Instron Universal Testing Machine and a specially designed instrument that enabled recording of tensile forces of stretched specimens during controlled cooking programs.

The tensile stress‐strain relationships revealed two types of deformation patterns. At strains of up to about 10% the fillets deformed as rubbery materials although with noticeable viscoelasticity. At larger strains the behavior was characterized by a progressive increase in stiffness and in the portion of irrecoverable deformation.

In relaxation tests at programmed temperature histories, force generation phenomena could clearly be monitored. Their extent and the temperature at which they occurred varied markedly with the fish species and the individual fillet's age, which suggests that they reflect the overall structural and physiological state of the tissue.
THE PROBLEM OF EQUILIBRIUM CONDITIONS IN STRESS RELAXATION ANALYSES OF SOLID FOODS1
Authors: PELEG M. , POLLAK N.
Published: February 2007

Since most solid food materials are biologically active or physically unstable, they do not reach mechanical equilibrium in the true sense of the term. Consequently, their stress relaxation data alone cannot provide information sufficient to decide whether these materials are true solids or not. The implications of this problem in the selection of rheological models for foods are emphasized and a method by which the problem can be bypassed is presented and its capabilities and limitations evaluated.
MODIFIED VISCOMETRIC METHOD FOR THE EVALUATION OF SWEET CORN MATURITY
Authors: SEBÖK A. , BÓDI J.
Published: February 2007

A modified viscometric method was developed for evaluating sweet corn maturity. The optimal deformation (shear) rate of the test was found to be 48.6 s‐1. A simple power‐law flow model was applied. Apparent viscosity correlated highly with maturity parameters. Freezing increased the viscosity of the corn slurries. Apparent viscosity and Back Extrusion maximum force were satisfactory indexes of quality for frozen corn.
RESEARCH NOTE THE TEXTURE OF COOKED RICE
Authors: DESHPANDE S. S. , BHATTACHARYA K. R.
Published: February 2007

The stickiness and consistency (an inverse estimate of tenderness) of cooked rice were measured by the sieve test and with the Haake consistometer. The values varied with the rice quality type. Stickiness was not appreciably affected by the water‐to‐rice ratio used during cooking, but was markedly reduced by storage especially in the cold, i.e. by starch retrogradation. Consistency was affected by both: it decreased with increasing water ratio and increased with storage. Stickiness was inversely proportional to consistency. Consistency of cooked rice varied with the force used in the consistometer test, from which it is postulated that cooked rice is a pseudoplastic system. Different rice samples should be compared only under identical rice‐to‐water ratio used for cooking and under identical force used for the consistency test.
BOOK REVIEWS
Authors: SHERMAN P.
Published: February 2007

Food Law Handbook. H. W. Schultz.

Protein Food Supplements. M. A. Maltz.
FLOW PARAMETERS OF SELECTED COMMERCIAL SEMI‐LIQUID FOOD PRODUCTS2
Authors: CANOVAS G. V. BARBOSA , PELEG M.
Published: February 2007

The rheological characteristics of samples of commercial apple sauce, baby food (banana and peach), mustard and ketchup were evaluated by two successive shearing cycles in a coaxial viscosimeter. It was found that generally, both the Herschel‐Bulkley and the modified Casson equations were equally good mathematical representatives of the experimental flow curves, especially after the sample has already been sheared once. The original Casson equation was generally a lesser appropriate model especially for the first flow curve. Time and shear effects on the flow curve features, and on the magnitude of the yield stress, were also studied. The results showed that although all the effects were roughly on the same order of magnitude, they varied considerably between the different types of products and within the same products of different manufacturers.
ANALYSING WARNER‐BRATZLER CURVES
Authors: KING N. L. , JONES P. N.
Published: February 2007

Forces required to deform and rupture samples of meat were measured in a modified Warner‐Bratzler device. A model is proposed to describe the shape of the plot of force against distance. This model was fitted by a least squares method to experimental curves obtained from (1) bovine longissimus dorsi muscles aged at 15°C for 1–7 days and then cooked at 80°C for 4 h, and (2) bovine biceps femoris muscles conditioned at 15°C for 24 h and then cooked at 80°C for 1–22 h. A plot of the variance between replicate forces, as a function of distance, exhibits two prominent peaks, one of which is thought to be associated with rupturing of fibre bundles, and the other with rupturing of perimysial connective tissue. Parameters calculated by fitting the model to replicate curves indicate that muscle fibres rupture in groups of fibre bundles. Hence, contrary to previous interpretations, initial yield involves rupture of connective tissue, as well as myofibrils. However, the number of fibre bundles forming a group capable of independent rupture varies according to the time‐temperature history of the sample, as do other parameters. The model permits relative contributions of fibre bundles and perimysial connective tissue to be estimated. In the samples studied here, perimysial connective tissue offered greater resistance to passage of the blade than did the fibre bundles.
CHARACTERIZATION OF TIME DEPENDENT FLOW PROPERTIES OF MAYONNAISE UNDER STEADY SHEAR
Authors: FIGONI PAULA I. , SHOEMAKER CHARLES F.
Published: February 2007

Time dependent flow properties of commercial mayonnaise have been measured at shear rates of 0.530, 0.169, 0.052, and 0.0169 s−1. The flow curves were fitted with a series of two first order rate functions. It appears that the time dependent flow properties of mayonnaise are better characterized by this model than with only the initial and final stress values of the stress decay curves or with a single first order rate function.
BOOK REVIEWS
Authors: SHERMAN P.
Published: February 2007

Physical Properties of Foods. M. Peleg and E. B. Bagley, eds.

Food Protein Deterioration, Mechanisms and Functionality. ACS Symposium Series 206. J. P. Cherry, ed.
THEORETICAL RESPONSES OF DIFFERENT RHEOLOGICAL MODELS TO A SINUSOIDAL COMPRESSION IN A TRANSIENT STATE
Authors: NOEL Y. , SALE P.
Published: February 2007

The sinusoidal compression imposed by the new device set up by SALE (INRA, Theix, France) is not an harmonic test. Therefore, a theoretical study of the deformation has been undertaken. The use of Carson‐Laplace trans forms allows one to establish the response of a Burgers model with the Hencky strain specific of the test. Simulations of simple rheological behaviour (elastic, viscous, vicoelastic) are presented as reference for future analysis of more complex behaviours of foodstuffs.
INTERNATIONAL COOPERATIVE TEST ON TEXTURE OF COOKED RICE
Authors: JULIANO BIENVENIDO O. , PEREZ CONSUELO M. , ALYO‐SHIN E. P. , ROMANOV V. B. , BLAKENEY ANTHONY B. , WELSH LYNSEY A. , CHOUDHURY NURUL H. , LILIA DELGADO L , IWASAKI TETSUYA , SHIBUYA NAOTO , MOSSMAN ALBERT P. , SIWI BERNARD , DAMARDJATI DJOKO S. , SUZUKI HIROSHI , KIMURA HIDESHI
Published: February 2007

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VISCOELASTIC BEHAVIOUR DURING THE GELATINIZATION OF STARCH II. EFFECTS OF EMULSIFIERS
Authors: ELIASSON A.‐C.
Published: February 2007

The viscoelastic behaviour during the gelatinization of starch in the presence of emulsifiers was studied in oscillatory shear. Glycerol‐monostearate and sodium stearoyl‐lactylate delayed the viscoelustic changes during gelatinization in a way which was intetpreted as related to the granules being stiffer in presence of these emulsifiers. Sodium abdecyl sulphate caused a destabilization of the granules, resulting in the rheological changes occurring at lower temperatures. Emulsifiers increased the viscous part of the rheological response. In a wary‐starch variety, where the amount of amylase is small, emulsifiers had only a small effect on gelatinization. It was concluded that the formation of an amylose‐lipid complex was of importance if an emulsifier was to exert an effect.
A GENERALIZED RHEOLOGICAL MODEL FOR INELASTIC FLUID FOODS1
Authors: OFOLI R. Y. , MORGAN R. G. , STEFFE J. F.
Published: February 2007

A versatile four‐parameter model is presented for the rheological characterization of inelastic fluid foods. The model has been shown to accurately represent shear stress versus shear rate, and apparent viscosity versus shear rate relationships for several food materials. By appropriate specification of the four parameters of the model, conventional rheological models used in fluid food analyses (power law, Bingham plastic, Herschel‐Bulkley, Casson, Heinz‐Casson, and Mizrahi‐Berk) can be obtained from the generalized equation.
MEASUREMENTS ON PASTRY MARGARINES USING A SLIDING PIN CONSISTOMETER
Authors: DAVEY KENNETH R. , JONES PETER N.
Published: February 2007

A sliding pin consistometer (SPC) has been shown to be suitable for differentiating significantly (P< 0.01) between three commercial pastry margarine products described as Hard, Medium and Soft at sample temperatures of 20 and 10°C. SPC average force values were related linearly (r = 0.98) to sample temperature over the range of 0.6 to 37°C. The SPC gives objective information which should be useful to manufacturers of pastry margarines as a simple quality test. It appears to have an advantage over more widely used extruders or penetrometers in that it is portable and easy to use.
ADAPTATION OF A BROOKFIELD (HBTD) VISCOMETER FOR MIXER VISCOMETRY STUDIES
Authors: CASTELL‐PEREZ M. E. , STEFFE J. F. , MORGAN R. G.
Published: February 2007

A low cost mixer viscometer system was developed using a Brookfield viscometer interfaced to a Hewlett Packard (HP) digital cassete drive. Tests were conducted in a Brookfield Small Sample Adapter with a specially designed flag type, mixer impeller. The system was tested for two power law type products (apricot puree and guar gum) with results being comparable to those obtained using a Rheometrics Fluids Spectrometer.
THE PERCEPTION OF FOOD TEXTURE ‐ THE PHILOSOPHY OF THE BREAKDOWN PATH
Authors: HUTCHINGS J. B. , LILLFORD P. J.
Published: February 2007

Many authors have drawn attention to the limitations of present texture testing methods. To a great extent this may be due to the assumption that the perception of the structural properties of foods is comprised of a series of single attributes. This philosophy may account for the failure of the single instrumental measurement as a reliable texture descriptor.

The present paper emphasises that texture perception is a dynamic sensory monitor of changes made to a food by processes occurring in the mouth. A general three dimensional model applicable to foods is postulated with “Degree of Structure”, “Degree of Lubrication” and “Time” as its axes. As each food is changed in the mouth, it describes its own “Breakdown Path” throughout the three dimensions. This approach is seen as the start of a general hypothesis for the physics and psychophysics of mastication.
EFFECT OF SAMPLE WEIGHT AND ORIENTATION ON THE TEXTURE PRESS FORCE OF APPLE SLICES
Authors: BIN FU , McLELLAN M. R.
Published: February 2007

Texture measurements of both fresh apple slices and steam‐blanched apple slices were studied using the FTC Texture Press. Sample weights of 40, 70, 100, 130, and 160 g slices were tested and three orientations (crosswise, lengthwise and randomly) of slices in the standard shear compression cell. The maximum shearing force approaches a constant when the sample weight reaches 70 g for blanched slices. Sample weights of 100 g for fresh slices and 100–130 g for blanched slices are suggested by these test results. Crosswise or random orientation of slices in the cell is preferred. Polynominal models of the maximum force (N) versus sample weight (g) are given and shown to be a closer fit over simple linear models.
VISCOSIMETRIC STUDIES ON ACID TYPE CHEESE TEXTURE
Authors: KOROLCZUK J. , MAHAUT M.
Published: February 2007

The apparent viscosities of market acid type cheese samples, containing 7.5 to 9.8% of total proteins, 12.7 to 19.9% of dry matter and 0 to 40% fat in dry matter, were measured with a coaxial cylinder viscometer, over the temperature range 5 to 40°C and the rate of strain 9 to 482 s‐1 for up to 2000 s. The logarithm of the apparent viscosity was a linear function of the logarithms of the rate of strain and of the shearing time. The activation energy of flow was about 35 to 40 kJ/mol for the nonfat cheese, while for cheese containing 30% fat in dry matter and for the temperature range between 15 and 20°C it increased to 100–130 kJ/mol. The logarithm of the apparent viscosity increased with increase of the protein content but the results were too scattered to allow prediction of the viscosity level for a single sample of known protein content.
DYNAMIC PROPERTIES OF ELASTIC MODULUS IN SOME HETEROGENEOUS GELS
Authors: HORIUCHI HISAYA
Published: February 2007

Study of phase difference and resonance methods for longitudinal vibration and the phase difference method for the shear mode showed that the dynamic moduli of clear homogeneous hydrocolloid gels were independent of frequency. However, those of heterogeneous gels including solid particles, such as agargelatin mixed gel or shiratama mochi and concentrated waxy corn starch gel, showed complex behavior with a flat line below 10 Hz and an inclining curve over a range of 100 Hz. The characteristic frequency dependence of the modulus was not caused by the characteristics or resonances of the experimental apparatus, but by the heterogeneous structure of the gel dispersed particles.
DYNAMIC VISCOELASTIC BEHAVIOR OF WHEAT GLUTEN: THE EFFECTS OF HYDROGEN BONDING MODIFICATION BY UREA AND DEUTERIUM OXIDE
Authors: INDA ARTURO E. , RHA CHOKYUN
Published: February 2007

Freeze‐dried wheat gluten was reconstituted with water, deuterium oxide, and 1M, 3M, and 5M aqueous solutions of urea. Differential scanning calorimetry and photoacoustic ultraviolet spectroscopy studies were conducted to obtain an independent assessment of the effects of these reagents. The storage and loss moduli of gluten reconstituted with water and deuterium oxide at the same frequency were higher for deuterated gluten. It was concluded that deuterium oxide does not cause conformational changes in gluten and that its main effect is a moderate increase in the strength of hydrogen bonding. For gluten reconstituted with urea, increasing urea concentration resulted in reduced frequency dependence of the storage modulus and a large decrease in the magnitude of the loss modulus, especially at the low frequencies. The increase in elasticity caused by urea was interpreted in terms of unfolding of the proteins upon disruption of hydrogen bonding. The interpretation of the rheological changes caused by urea and deuterium oxide is consistent with the results obtained by calorimetry and ultraviolet spectroscopy.
CONTRIBUTION OF AIR‐AND BONE‐CONDUCTION TO THE CREATION OF SOUNDS PERCEIVED DURING SENSORY EVALUATION OF FOODS
Authors: DACREMONT C. , COLAS B. , SAUVAGEOT F.
Published: February 2007

The noises perceived during sensory evaluation of foods are transmitted to the innerear by both air and bone conduction. The contribution of the two conductions was studied for six foods “croquant” (crunchy), “craquant” (crackle) and “croustillant” (crispy), by six panelists. It was studied by reconstituting the attenuation of the air and bone conduction records needed to imitate sound actually heard during sensory evaluation of foods. The eating technique (bite or chew) modified the contribution of air‐ and bone‐conduction to auditory sensation. Differences were shown between foods, but they could not clearly distinguish between the kinds of food. Modifying the attenuation of the air‐ and bone‐conduction records was not enough. The bone‐conduction records had to be attenuated over a frequency range around 160 Hz, which is the resonance frequency of the mandible. The air‐conduction records had to be attenuated at a frequency range around 160 Hz and amplified at a frequency range around 3,500 Hz in order to match the action of the middle‐ear muscles which behave differently when sounds were generated inside or outside the mouth.
MODELING PROTEIN GELATION AND APPLICATION OF ENTROPY ELASTICITY TO UNDERSTAND PROTEIN GEL PROPERTIES
Authors: HSIEH YIN LIANG , REGENSTEIN JOE M.
Published: February 2007

The theory of rubber elasticity is reviewed to study several properties of the three dimensional protein gels, e.g., the number of sulfhydryl binding sites per protein polypeptide. Alternatively, the theory of gelation can be used to explore the protein aggregating reactions, to evaluate the required number of protein aggregates and the rate that the different size proteins aggregate when gelling.
AREA‐ AND PERIMETER‐DEPENDENT PROPERTIES AND FAILURE OF MATURE‐GREEN AND RED‐RIPE TOMATO PERICARP TISSUE
Authors: JACKMAN ROBERT L. , STANLEY DAVID W.
Published: February 2007

The influence of tomato fruit ripeness on area‐ and perimeter‐dependent properties and dominant failure mechanisms of pericarp tissue were investigated. Tissue discs from mature‐green and red‐ripe fruit were punctured with a flat‐ended cylindrical probe and compressed with a flat plate at a constant rate of deformation. Approximately linear force‐deformation curves were obtained to tissue failure by both puncture and flat plate compression, interrupted by a region of pseudoplastic deformation at a relatively low initial bioyield force. Based on estimated area‐ and perimeter‐dependent coefficients and firmness (force/deformation) values, initial bioyielding of tissue appeared to be associated with an abrupt increase in cell‐to‐cell compaction. Puncture of mature‐green tissue led to premature failure induced by shearing or rupture of tissue at the probe perimeter. The contribution to puncture of perimeter‐dependent or shear‐associated forces and a putative “zone of influence” increased markedly with ripening, while the contribution of area‐dependent or compression associated forces generally decreased. A concomitant decrease in failure force and firmness with ripening reflected a general loss of both tissue compression and shear strengths. These results suggested that the dominant mode of tissue failure changed with ripening, from cell relaxation and rupture to cell debonding. The data obtained in this study emphasize the need to exercise caution in the interpretation of force‐deformation parameters derived from puncture tests alone.
LOW DEFORMATION AND WATER HOLDING MEASUREMENTS OF WHOLE AND COMMINUTED MEAT ORIGINATING FROM TWO MUSCLES OF DIFFERENT FIBRE TYPE COMPOSITION
Authors: MEYER CHRISTINE , EGELANDSDAL BJØRG
Published: February 2007

The rheological properties and water uptake in the white muscle m. cutaneus trunci and the red muscle m. masseter of Norwegian red cattle were compared. The two muscle systems were examined intact, ground and chopped, at two different salt levels, and unheated as well as heated to 70C. Three different rheological parameters were recorded: the complex modulus, the phase angle and a parameter measuring nonlinear viscoelastic properties (called deformation index). The white muscle had, in general, the highest complex modulus, the highest phase angle and the lowest deformation index. The variation imposed on the data by the pH variation accompanying different fibre types, made direct comparisons between the two muscles difficult. It is suggested that the complex modulus for unheated systems was most sensitive to fibre type differences. The different rheological parameters recorded revealed different sensitivity to the variables investigated. The complex modulus, measured on unheated systems, were insensitive to the degree of comminution while both the phase angle and the deformation index were sensitive to this mechanical treatment. To record different rheological parameters might therefore be useful when establishing nondestructive viscoelastic measurements for on‐line quality control in factories. However, it is felt that such measurements must be supported by other rapid measurements to fully utilize their potential.
INSTRUMENTAL DETERMINATION OF ELASTICITY OF MARSHMALLOW 1
Authors: KALETUNC G. , NORMAND M.D. , JOHNSON E.A. , PELEG M.
Published: February 2007

Marshmallows of a national and supermarket brand were subjected to four successive compression‐decompression cycles using a computer interfaced Universal testing machine and the total and recoverable work in each cycle determined. The two brands were significantly different. Differences were maintained irrespective of the deformation rate (10 and 20 mm.min–1), the magnitude of imposed strain in the range of 15–40% and the time between the cycles (0, 30 and 60 s). It appears that the discriminatory power of the test decreases as the magnitude of the imposed strain increases.
COMPARISON OF THE CONFORMATION OF TOMATO PECTINS WITH APPLE AND CITRUS PECTINS
Authors: KOKINI J.L. , CHOU T.C.
Published: February 2007

The conformation of hot break tomato pectins in water/glycerol solutions as a function of degree esterification was studied and compared with the conformation of apple and citrus pectin using reduced storage [G′]R and loss [G″]R moduli and the theories of Marvin and McKinney for rod‐like behavior and those of Rouse as well as Zimm for random coil conformation. In all three cases the theory of Zimm implying dominant hydrodynamic interactions fit the experimenal data best. This is consistent with current knowledge on chemical structure of pectin where the charged uronides clearly readily interact with each other.
CHANGES IN RHEOLOGICAL PROPERTIES OF HYDROXYPROPYL POTATO STARCH PASTES DURING FREEZE‐THAW TREATMENTS II. EFFECT OF MOLAR SUBSTITUTION AND CROSS‐LINKING
Authors: KIM HAK RYANG , ELIASSON ANN‐CHARLOTTE
Published: February 2007

The effects of molar substitution (M.S.) and cross‐linking on the freeze‐thaw stability of hydroxypropyl potato starch pastes were studied by following the changes in the rheological behaviour during heat treatment of the thawed starch pastes, and by determination of syneresis. In addition, differential scanning calorimetry (DSC) was used to investigate the thermal transition properties of the starch pastes that exhibited syneresis. With increasing M.S., the changes in both complex modulus (G*) and phase angle (δ) indicative of destabilization, and starch paste syneresis were delayed with regard to the number of freeze‐thaw cycles. When a starch paste showed a peak in G*, related to syneresis, it also showed a thermal transition peak in the DSC measurements. The enthalpy value decreased with increasing M.S., and it appeared to be related to the extent of syneresis and the magnitude of the peak in G*. Comparison of the rheological behaviour of hydroxypropyl potato starch pastes and hydroxypropyl and cross‐linked potato starch pastes, suggested that the former were gradually transformed into coarsely aggregated structures while the latter became diluted starch dispersions, due to shrinkage of swollen starch granules and their disruption.
COMPACTION CHARACTERISTICS OF AGGLOMERATED COFFEE DURING TAPPING
Authors: BARLETTA B.J. , KNIGHT K.M. , BARBOSA‐CÁNOVAS G.V.
Published: February 2007

Three brands of instant coffee were used as model agglomerated powders. They were exposed to compaction in a tap density tester. Experiments were done confining samples of instant coffee in graduated cylinders with several diameters, i.e., 1.6, 2.0 and 2.4 cm; and different product heights, i.e., 3.2, 6.3, and 12.5 cm. Increased attrition was noticed with the number of tappings, which ranged from 0 to 10,000 taps. Changes in bulk density were fitted to two‐parameter models used for compaction of food powders, using nonlinear regression. New three and four‐parameter models were proposed, and their fit to experimental data was also examined. The fit of these new models was better than that of previous ones, indicating that the combined effect of attrition and compaction cannot be properly described by models containing less than three parameters. The container diameter, product height, and particle size were found to affect the parameters’ estimates for the models examined.
FLOW PROPERTIES OF OAT PROTEIN DISPERSIONS1
Authors: MA C.‐Y.
Published: February 2007

The effects of protein and salt concentrations, anions, and heating on thejlow properties of oat globulin dispersions were studied. Flow properries were greatly influenced by the conformation and state of aggregation‐dissociation of the oat protein polypeptides. Chemical modijications including deamidation, acylation, trypsin hydrolysis and linoleate treatment also change the flow characteristics of oat protein concentrates and isolates.
INFLUENCE OF THE SKIN ON PUNCTURE PROPERTIES OF CHILLED AND NONCHILLED TOMATO FRUIT
Authors: JACKMAN ROBERT L. , STANLEY DAVID W.
Published: February 2007

The puncture properties (firmness, toughness) of tomato skin and its influence on the overall puncture properties of mature‐green fruit during ambient temperature (22C) ripening or chilled (5C) storage were estimated from the difference between whole fruit puncture force‐deformation behaviour and that measured with the skin removed. Although the firmness of the skin of nonchilled fruit did not change significantly (p > 0.05) over 28 days of ripening, its contribution to overall puncture firmness increased from about 25 to 70%. Both skin toughness and its contribution to overall puncture toughness doubled within the first week of ripening of nonchilled fruit. The firmness of chilled fruit skin decreased (p > 0.05) only after 16 days of storage, but its contribution to overall puncture firmness remained constant at 25–30%. Both the toughness of the skin of chilled fruit and its contribution to overall puncture toughness remained constant during storage. Possible artifacts in the measurement of puncture properties of chilled fruit are discussed. The results are consistent with a toughening of tomato skin during early stages of ripening of nonchilled fruit that somewhat compensates for a rapid reduction in pericarp tissue integrity, and with an increase in firmness or rigidity of tomato skin and underlying tissue(s) during chilled storage of fruit.
SPECTRAL COMPOSITION OF EATING SOUNDS GENERATED BY CRISPY, CRUNCHY AND CRACKLY FOODS
Authors: DACREMONT C.
Published: February 2007

Separate air and bone conducted food sounds generated by six subjects biting into eight foods were recorded and analysed by a fast Fourier transform (FFT) signal analyser. A panel of 60 subjects classified the 8 foods according to their texture: crispy, crunchy and crackly and these textural characteristics were described by spectral characteristics of biting sounds. Crispy foods (such as extruded flat breads) were found to generate high pitched sounds that show a high level of frequencies higher than 5 kHz, especially for air conduction. Crunchy foods (such as raw carrot) generate low pitched sounds with a characteristic peak on frequency range 1.25 to 2 kHz for air conduction. And crackly foods (such as dry biscuits) generate low pitched sounds with a high level of bone conduction. We hypothesize that discrimination between crunchy and crackly foods could be due to vibrations propagated by bone conduction that also generated vibrotactile sensations.
EFFECTS OF pH ON WHEY PROTEIN CONCENTRATE GEL PROPERTIES: COMPARISONS BETWEEN SMALL DEFORMATION (DYNAMIC) AND LARGE DEFORMATION (FAILURE) TESTING
Authors: TANG QINGNONG , McCARTHY OWEN J. , MUNRO PETER A.
Published: February 2007

The effects of pH on the properties of gels prepared from commercially available whey protein concentrate were investigated by nondestructive dynamic shear testing with a Bohlin Rheometer and by large deformation compression, tension and penetration tests with an Instron Universal Testing Machine. Dynamic storage modulus, G′, and the slopes of force‐deformation curves from all three types of large deformation test exhibited maxima at or near both pH 4 and pH 7. Electrostatic interactions were the dominant factor in explaining this behaviour. Failure displacements in the large deformation tests generally increased with increase in pH. It is proposed that the formation of disulphide bonds at pH values above 6.5 is the dominant factor in explaining this behaviour. Failure forces in the large deformation tests remained low up to pH 6.5, increased rapidly to a maximum at pH 7–7.5 and then decreased again. The variation in both electrostatic interactions and disulphide bonds with pH is necessary to explain this behaviour. The combination of penetration failure force, penetration failure displacement and penetration rigidity (slope of force‐displacement curve) provided as much qualitative understanding of the variation of gel properties with pH as similar information from any other single test.
SURFACE PROPERTIES OF PROTEIN LAYERS ADSORBED FROM MIXTURES OF GELATIN WITH VARIOUS CASEINS
Authors: GALAZKA VANDA B. , DICKINSON ERIC
Published: February 2007

We report surface tensions and surface shear viscosities of protein layers adsorbed from mixtures of gelatin +αs11‐casein, β‐casein, k‐casein or sodium caseinate. Under conditions where the two protein components carry opposite net charges, the combined experimental data at 25C and neutral pH are consistent with a two‐layer model of the mixed protein film. The surface properties of sodium caseinate lie intermediate between those for the two major individual caseins (αs1 and β).
FACTORS AFFECTING THE VISCOELASTIC PROPERTIES OF ALBUMEN FOAMS1
Authors: FUJIOKA TOSHIKO , MATSUMOTO SACHIO
Published: February 2007

The stability of foams prepared from egg albumen could be characterized by the changes in viscoelastic parameters obtained from measurements of stress relaxation and creep in compression. The initial relaxation modulus and instantaneous elasticity increased with time for about 40 min after the preparation of the foams because of the slow rate of adsorption of ovalbumin molecules to the air/water interface of the liquid film. These moduli then decreased with aging due to the thinning and rupture of the liquid films in the foam. The rate of decrease of the moduli was accelerated by reducing the concentration of sugar or by lowering pH in the aqueous phase of the liquid films. The presence of a certain amount of sugar seems to control the drainage rate of water from the liquid films, while the electrostatic repulsion between the inside surfaces of the liquid films may decrease in the acid region according to the reducing charged potential at the inside surfaces adsorbed ovalbumin molecules.
COMPARISON OF MATHEMATICAL MODELS APPLIED TO THE RENNET COAGULATION OF SKIM MILKS
Authors: O'CALLAGHAN DONAL J. , GUINEE TIMOTHY P.
Published: February 2007

The coagulation of renneted skim milks was monitored by dynamic measurement of elastic shear modulus (G) based on low amplitude oscillation. Four alternative time‐dependency models were fitted to the measurements and compared with respect to their ability to describe the development of curd firmness and their usefulness in deriving parameters of practical interest in cheesemaking.

All models described the development of G over the course of the experimental time‐scale (≈ 60 min), with the Scott‐Blair and Carlson models following the experimental course of G more accurately than the other models. The fit of the Douillard model was consistent with a systematic error in the region of onset of gelation, owing to its nonsigmoidal nature. The fit of the linearized Scott Blair model was poor at the upper end of the experimental range of G.

Apart from gel time as defined by G = 0.2 Pa, there was no significant difference between the Carlson and Scott Blair models in simulating most coagulation parameters, including set‐to‐cut time, firmness at 2.4 ks, rate of curd firming and time of maximum curd firming rate.

Where significant differences occurred between the Carlson and Scott Blair models, on one hand, and either the Douillard or linearized Scott Blair model on the other, as for set‐to‐cut time, the mean deviations from experimental data were smaller when using the former models.
TOMATO PERICARP TISSUE RESONANCE AND ITS USE IN TEXTURE EVALUATION
Authors: JACKMAN ROBERT L. , TREGUNNO NANCY B. , GOFF H. DOUG , STANLEY DAVID W.
Published: February 2007

The use of resonance properties, measured by dynamic oscillation using a constant stress rheometer, as textural parameters for excised pericarp tissue of tomato (Lycopersicon esculentum Mill cv Trust) fruit during 21 days of ambient temperature ripening was assessed relative to the large‐deformation behavior measured by flat‐plate compression. The resonance frequency (fr) of excised tissue discs decreased significantly (P < 0.05) over the first 9–12 days, and then approached a relatively low and constant value with subsequent ripening. A significant (P < 0.05) increase in associated resonance strain amplitude (ymax) became apparent after the first 9–12 days of tomato fruit ripening. Ripening‐associated changes in bioyield and failure strengths, toughness, and apparent elastic and failure deformability moduli derived from flat‐plate compression tests were similar to those observed for tissue fr. Results were consistent with a change in the dominant mode of tissue failure from cell relaxation and rupture to debonding after 9–12 days of fruit ripening. A significant (P < 0.05) semilogarithmic relationship was observed between fr, but not ymax, and compression parameters, allowing for reasonable prediction of large‐deformation behavior on the basis of measurement of only fr. The results demonstrate that resonance frequency may provide a useful parameter in the evaluation of tomato pericarp tissue texture.
MIXER VISCOMETER CONSTANT (k) FOR THE BROOKFIELD SMALL SAMPLE ADAPTER AND FLAG IMPELLER
Authors: BRIGGS JENNI L. , STEFFE JAMES F.
Published: February 2007

The mixer viscometer constant (k1) of a Brookfield viscometer equipped with a flag impeller and small sample adapter was determined using the slope and matching viscosity methods. Results showed that k’ was equal to a constant value of 2.92 rad−1 using the slope method and found to be a function of angular velocity (Ω), k’= 2.54(Ω)−0.176, using the matching viscosity method. An example problem illustrating how the mixer viscometry principle can be used to determine the relationship between apparent viscosity and average shear rate is presented.
RHEOLOGICAL BEHAVIOR OF COCOA DISPERSIONS WITH COCOA BUTTER REPLACERS
Authors: FANG T. , ZHANG H. , HSIEH T.T. , TIU C.
Published: February 2007

The steady shear viscosity and yield stress of cocoa powder dispersed in three cocoa butter replacers (CBRs) are measured over a wide range of powder concentration and temperature. The flow activation energies of the three CBRs are nearly the same, and close to that of cocoa butter. Values of intrinsic viscosity of cocoa powder dispersed in corn oil and Socolate 36–38 are in the range of 4.0–5.0, (similar to that in cocoa butter), suggesting that these two CBRs are good cocoa replacers. A lower value of intrinsic viscosity is found for the powder dispersed in Super YZ‐2. Viscosity measurements indicate that all three CBR dispersions exhibit Newtonian behavior at low volume fraction, but non‐Newtonian shear thinning characteristics when the volume fraction φ > 0.3 at 60C. The non‐Newtonian behavior can be described by the Casson model when φ exceeds a critical value, φmo, the maximum packing fraction at zero shear. The yield stress can be related to the powder volume fraction using a four‐parameter equation originally proposed by Zhou et al. (1995).
RHEOLOGICAL PROPERTIES OF BEDS OF RAISINS
Authors: KOSTAROPOULOS A.E. , MANDALA I.G. , SARAVACOS G.D.
Published: February 2007

The rheological properties of beds of Sun‐dried Sultana and Corinth raisins equilibrated to various moisture levels were investigated. Raisin beds of fixed bulk density at various configurations were compressed in a cylindrical test cell, and the apparent modulus and the two constants of an empirical model were estimated from the linearized stress/strain and relaxation curves. Beds of black Corinth raisins were more elastic than Sultana (seedless) raisins at moistures lower than 18%, but both types of raisins showed similar rheological behavior at higher moistures. The unrelaxed stress of all beds, after 10 min of relaxation, was about 25% of the initial stress. Beds of randomly mixed raisins of different moisture content appeared to be more elastic when the proportion of the moist raisins was increased. The apparent modulus of columns of raisins decreased as the number of raisins per column and the number of adjoining rows were increased.
GEL CHARACTERISTICS OF β‐LACTOGLOBULIN, WHEY PROTEIN CONCENTRATE AND WHEY PROTEIN ISOLATE
Authors: TWOMEY MYRA , KEOGH M. KIERAN , MEHRA RAJ , O'KENNEDY BRENDAN T.
Published: February 2007

The gelation characteristics of β‐lactoglobulin, whey protein isolate and whey protein concentrate at varying levels of protein (6–11%), sodium chloride (25–400 mM), calcium chloride (10–40 mM) and pH (4.0–8.0) were studied in a multifactorial design. Small scale deformation of the gels was measured by dynamic rheology to give the gel point (°C), complex consistency index (k*), complex power law factor (n*) and critical strain (γc). The gel point decreased and turbidity increased with increasing calcium level. The denaturation temperature measured by differential scanning calorimetry was measured at higher pH values. Large scale deformation at 20% and 70% compression was measured using an Instron Universal Testing machine. The true protein level had the largest effect on the stress required to produce 20% and 70% compression and on the consistency (k*) of the gels.
BOOK REVIEW
Authors: BOURNE MALCOLM
Published: February 2007

FIRST INTERNATIONAL SYMPOSIUM ON FOOD RHEOLOGY AND STRUCTURE, Editors E.J. Windhab and B. Wolf. 1997. Vincentz Verlag, Hannover, Germany. 440 pages, 150 DM. $85.
SENSORY AND TEXTURAL EVALUATION OF MAINE WILD BLUEBERRIES FOR THE FRESH PACK MARKET
Authors: DONAHUE DARRELL W. , WORK THERESE M.
Published: February 2007

Maine wild blueberries were sized according to berry diameter into three size classes; ≤ 8 mm, 9–10 mm and 11–12 mm. A consumer sensory panel was asked to indicate their opinion of flavor, texture and overall attributes using a 9‐point hedonic scale. Subsamples of berries were subjected to a compression test using an Instron Materials testing machine, measuring force and deformation to point of rupture of individual blueberries. Berries ≤ 8 mm were significantly lower in sensory acceptability for all three attributes evaluated. No significant difference was found between 9–10 mm and 11–12 mm samples. Both were rated “like moderately”. Ranked preference data indicated a significant preference for the larger 11–12 mm berries. The results of the compression tests revealed significant differences among all size classes with respect to the apparent modulus. A linear relationship was found between the “texture” sensory attribute and the elastic modulus.
A MEMBRANE MODEL FOR ELASTIC DEFLECTION OF INDIVIDUAL PLANT CELL WALLS
Authors: DAVIES G. C. , HILLER S. , BRUCE D. M.
Published: February 2007

Deformation of plant cells by a fine probe can provide a measure of cell wall stiffness which is responsible for many of the mechanical properties of the plant. An example system of potato tuber parenchyma cells is used, and cell wall deformation approximated as the axisymmetric deformation of a circular membrane made from a nonlinear‐elastic material with a Mooney strain energy function. A system of differential equations describing the shape of the membrane is derived and solved. The effects of turgor and initial cell wall strain on the force required to produce a given deflection and on the shape of the deformed cell are examined. Values for the elastic constants of the wall material are proposed, guided by statistical data for cell size and stiffness obtained from micropenetration tests.
RHEOLOGICAL BEHAVIOUR OF MIXED GELS OF WHEAT STARCH AND ETHYL(HYDROXYETHYL)CELLULOSE
Authors: LARSSON HELENA , ELIASSON ANN‐CHARLOTTE
Published: February 2007

Gelatinisation of wheat starch (6%) in the presence of a nonionic amphiphilic polymer, ethyl(hydroxyethyl)cellulose (EHEC) has been studied. Concentration (0.1–1 wt %) and molecular weight (approximately 80,000–350,000) of EHEC were shown to influence the rheological behaviour of the pastes at 60C, and the gels after 340 min storage at 25C. Two separated regions in the mechanical spectra (0.01–10 Hz) were observed for the mixed gels at 25C with the highest concentration of EHEC. This behaviour suggested long range (overall gel properties) and the influence of short range (molecular entanglements) interactions.
COMPARISON OF OBSERVED RHEOLOGICAL PROPERTIES OF HARD WHEAT FLOUR DOUGH WITH PREDICTIONS OF THE GIESEKUS‐LEONOV, WHITE‐METZNER AND PHAN‐THIEN TANNER MODELS
Authors: DHANASEKHARAN M. , HUANG H. , KOKINI J.L.
Published: February 2007

The measured rheological behavior of hard wheat flour dough was predicted using three nonlinear differential viscoelastic models. The Phan‐Thien Tanner model gave good zero shear viscosity prediction, but overpredicted the shear viscosity at higher shear rates and the transient and extensional properties. The Giesekus‐Leonov model gave similar predictions to the Phan‐Thien Tanner model, but the extensional viscosity prediction showed extension thickening. Using high values of the mobility factor, extension thinning behavior was observed but the predictions were not satisfactory. The White‐Metzner model gave good predictions of the steady shear viscosity and the first normal stress coefficient but it was unable to predict the uniaxial extensional viscosity as it exhibited asymptotic behavior in the tested extensional rates. It also predicted the transient shear properties with moderate accuracy in the transient phase, but very well at higher times, compared to the Phan‐Thien Tanner model and the Giesekus‐Leonov model. None of the models predicted all observed data consistently well. Overall the White‐Metzner model appeared to make the best predictions of all the observed data.