bluuebunny/crossref_metadata_2025 huggingface dataset:
EFFECT OF HOLDING TUBE CONFIGURATION ON THE RESIDENCE TIME DISTRIBUTION OF MULTIPLE PARTICLES IN HELICAL TUBE FLOW
Authors: PALAZOGLU T. KORAY , SANDEEP K.P.
Published: February 2007

The flow of solid‐liquid mixtures in a novel tube configuration was investigated and the results were compared to those obtained with a single‐helical tube configuration. Residence time distribution (RTD) of polystyrene and acrylic particles as affected by different processing parameters was determined. The studied parameters included flow rate, carrier fluid consistency, particle concentration, and curvature ratio of the helical tube. Curvature ratio and flow rate were found to be the most important factors affecting the RTD of particles. Interactions between particles appeared to be important, as the RTD of acrylic particles decreased significantly whereas that of polystyrene particles increased slightly upon mixing the two types of particles.
EFFECTS OF CONTROLLED MIXING ON THE RHEOLOGICAL PROPERTIES OF DEEP‐FAT FRYING BATTERS AT DIFFERENT PERCENT SOLIDS
Authors: LEE S. , NG P.K.W. , STEFFE J.F.
Published: February 2007

Two types of deep‐fat frying batters (adhesion and tempura batters) were mixed under controlled conditions at different percent solids to study their rheological properties and coating characteristics. Optimum degree of mixing of a batter was defined as the conditions that gave the maximum amount of batter retention (coating thickness) on a coated probe. Batter with higher percent solids needed more energy to achieve optimum mixing. In the case of batter retention, batters with higher percent solids required a longer period of time to stabilize dripping. Thixotropic behavior was observed in both adhesion and tempura batters. When relating batter rheology with fried food quality, it was found that undermixing a batter had more detrimental effects on fried food quality than overmixing a batter.
DETERMINATION of the MIXING INDEX of PADDY GRAINS UNDER VIBRATING CONDITIONS
Authors: DAS IPSITA , DAS S.K. , BAL SATISH
Published: February 2007

Mixing of ingredients is an important operation in processing of food for obtaining the better quality product. A laboratory set‐up capable of modulating both frequency and amplitude of vibration of the grain bed was used to determine the mixing indices of paddy grains under varied experimental conditions. the mixing indices of three different types of paddy grain for three different grain bed depths were determined. the parameters varied were the vibration amplitude, frequency and the mixing time, respectively from 2 to 10 mm, 10 to 50 Hz and 5 to 120 s. Three varieties of paddy (short bold, medium slender and long slender) were used in the experiments with different length‐breadth ratio (slenderness ratio, μ, of 5.77, 4.48 and 2.70). Response surface methodology was adopted to optimize the amplitude and frequency of vibration of the mixing device. the results revealed that, the optimum frequency and amplitude of vibration for the medium slender (μ= 4.48) variety of paddy were 20–22 Hz and 8–9 mm, respectively for all the three grain bed depths of 25, 12 and 6 mm. Irrespective of grain bed depth, all the three different types of paddy showed maximum mixing indices value after 1 min of mixing. Extending the mixing time did not have any effect on mixing indices. the effect of bed depth was found to be insignificant for short bold variety of paddy.
PRESSURE DROP and FRICTION FACTOR IN HELICAL HEAT EXCHANGERS UNDER NONISOTHERMAL and TURBULENT FLOW CONDITIONS1
Authors: CORONEL P. , SANDEEP K.P.
Published: February 2007

This study involved the determination of pressure drop and friction factor (f) in helical heat exchangers under turbulent flow conditions. the experiments were conducted in helical heat exchangers, with coils of two different curvatures ratios (d/D = 0.114 and 0.078) at various flow rates (9.46 × 10−5 ‐ 6.31 × 10−4 m3/s) and end‐point temperatures (20, 93.3, 121, 149C). the computed friction factor (f) in the helical heat exchanger was compared to published correlations, and it was found that the experimental data was in good agreement with them. In addition, correlations to determine pressure drop based on the Reynolds number, curvature ratio, and temperature were developed.
MATHEMATICAL MODEL to PREDICT EFFECT of TEMPERATURE ABUSE IN MAP SYSTEMS APPLIED to PACIFIC HAKE (MERLUCCIUS AUSTRALIS)
Authors: SIMPSON R. , ALMONACID S. , ACEVEDO C. , CORTÉS C.
Published: February 2007

This paper describes the development of a mathematical model to predict consequences of temperature abuse on shelf‐life of Pacific Hake packed in modified atmosphere. the model includes simultaneous heat and mass transfer phenomena coupled with a predictive shelf‐life model for packed fish. the model was solved using an explicit finite difference scheme. the simulated results are in good agreement with the experimental results. the model predicted temperature, gas concentration and relative humidity within < 0.6[°C], < 1.43% and 3%, respectively. Shelf‐life model predicts that, even if the fraction of the total storage time at an abusive temperature is small (4.3%), the reduction in shelf‐life can be significant (25%). the predicted shelf‐life without temperature abuse is consistent with literature results. Optimum MAP systems must reach pseudoequilibrium headspace gas composition which maximize the shelf‐life of food considering possible environmental temperature abuses.
THE EFFECTS of SOME PROCESSING CONDITIONS ON OIL POINT PRESSURE of LOCUST BEAN
Authors: OWOLARAFE O.K. , ADEGUNLOYE A.T. , AJIBOLA O.O.
Published: February 2007

The effect of moisture content (4.5, 6.0, 8.5 and 10.0% wet basis) heating temperature (70, 85, 100 and 120C) and heating time (15, 20, 25, 30 min) on the oil point pressure of locust bean seed was investigated. It was found that oil point pressure is a minimum near moisture content of 6.0% (wet basis) and increased with increasing or decreasing moisture content from this value. the oil‐point pressure decreased with an increase in heating temperature and heating time except at excessive heating temperatures and retention (heating times). On the overall the oil point pressure has a highest value of 4.34 MPa for sample with a moisture content of 4.5% (wet basis), heating temperature of 120C and heating time of 30 min; and lowest value of 2.90 MPa for sample with moisture content of 6.0% (wet‐basis), heating temperature of 100C and heating time of 30 min.
KINETICS OF LYCOPENE DEGRADATION IN TOMATO PUREE BY HEAT AND LIGHT IRRADIATION
Authors: SHI JOHN , LE MAGUER MARC , BRYAN MIKE , KAKUDA YUKIO
Published: February 2007

Lycopene as a natural antioxidant may provide protection against a broad range of epithelial cancers. Tomatoes and tomato‐based food products are a major source of lycopene compounds. Thermal processing is the main procedure in tomato puree production. Heat and light induces lycopene oxidation and isomerization of the all‐trans form to the cis form. The level of cis‐isomers increases as treatment time increases but only for a short period during the beginning of the treatment. The major effect of thermal processing was a significant decrease in the total lycopene content. Lycopene is relatively stable if heated at temperatures below 100C, but the duration of heating must be taken into consideration. The kinetics of lycopene degradation was analyzed. A shorter period of time of heating and less light irradiation in processing and storage would reduce lycopene degradation to a great extent.
MODELING and EXPERIMENTAL STUDY ON DRYING of APPLE SLICES IN A CONVECTIVE CYCLONE DRYER
Authors: AKPINAR E. KAVAK , BICER Y. , MIDILLI A.
Published: February 2007

The main objective pursued in this paper is to experimentally investigate the single layer drying behavior of apple slices in a convective type cyclone dryer and also to perform the mathematical modeling by using single layer drying models in literature. the experiments were conducted at drying air temperatures of 60, 70 and 80C in drying air velocities of 1 and 1.5 m/s. It was concluded that apple slices with the thickness of 12.5 mm would perfectly dry in the ranges of 280–540 mm while those with the thickness of 8 mm would dry in the ranges of 180–320 min in these drying conditions by using convective type cyclone dryer. Additionally, the mathematical model describing the single layer drying curves was determined by nonlinear regression analysis, and the logarithmic model was selected as the most suitable model to obtain the drying curve equation of apple slices. Considering the parameters such as drying time, drying rate, moisture transfer, velocity and drying air temperature it is suggested that the apple slices be dried at the above optimum processing conditions.
OHMIC BLANCHING of MUSHROOMS
Authors: SENSOY ILKAY , SASTRY SUDHIR K.
Published: February 2007

Mushrooms that are to be canned are typically blanched for long times to preshrink them. Our objectives were to compare the weight and volume loss of mushrooms during blanching under conventional and ohmic heating conditions and to investigate waveform and frequency effects of ohmic heating. In our setup, it was possible to heat mushroom caps with ohmic heating to above 70C in 40 s while maintaining a 50% solid mushroom content in water. Weight loss predicted using previously published kinetic models, and internal mushroom temperature data suggested that substantially greater shrinkage occurred than attributable to temperature alone. Shrinkage predictions were more consistent with experimental values when the temperature of the surrounding medium was used as a basis, suggesting that some combination of thermal and nonthermal permeabilization mechanisms may be in action. Ohmic blanching offers the advantage of being able to maintain a high solids content during blanching compared to the use of excessive amounts of water (60 kg/400 L) in conventional blanching. Frequency and waveform did not affect the weight loss during ohmic blanching in the range studied. Ohmic heating may have potential for this application due to its rapid, volumetric heating rates, and the enhancement of mass transfer even at relatively low temperatures.
DEVELOPMENT and EVALUATION of MICROWAVE HEATING of APPLE MASH AS A PRETREATMENT to PRESSING
Authors: ROBERTS J.S. , GERARD K.A.
Published: February 2007

Fuji, McIntosh, and Red Delicious apple mashes were heated in a 2450 MHz oven to achieve bulk temperatures of 40, 50, 60, and 70C. Three kilograms of mash at a depth of 0.016 m heated using 1500 W were the optimum parameters to heat apple mash in the microwave. Variety of the apple mash was shown not to have a significant effect on the heating performance. Comparing actual bulk temperature to the predicted bulk temperatures of 40, 50, 60, and 70C showed reproducibility of heating these mashes using microwave energy. Average variation between actual and predicted bulk temperatures were 1.48C for the Fuji mash, 0.98C for the McIntosh mash, and 1.13C for the Red Delicious mash. In addition, regional heating was investigated and four distinct regions of heating were observed: the corner, the edge, the middle, and the center. Color and moisture content of the mash were also measured and compared to unheated mash at 21C.
SET POINT DETERMINATION FROM SENSORY EVALUATIONS FOR FOOD PROCESS CONTROL
Authors: KUPONGSAK S. , TAN J. , HATEM I. , LU W. , GUTHRIE B. , TANOFF M.
Published: February 2007

Sensory evaluation is often the ultimate measure of food quality, but food process control relies on instrumental measurements. Effective techniques are needed to convert desired sensory quality targets into instrumental process set points. This paper describes techniques developed for determining instrumental process set points from sensory evaluations. Various cases and different approaches depending on the nature of the sensory‐instrumental relationships are outlined. the major issues addressed include additional constraints for underdetermined cases and reverse mapping with neural networks for nonlinear multivariate cases. These techniques were illustrated and tested with experimental data based on waffie samples. Seven sensory attributes were evaluated by trained panelists and instrumental measurements were obtained with a color computer vision system. For nonlinear multivariate cases, reverse mapping with neural networks successfully mapped sensory measurements to instrumental process set points with average errors less than 1.3%. the results demonstrate the effectiveness of the techniques developed.
COFFEE DRYING IN A ROTARY CONDUCTION‐TYPE HEATING UNIT
Authors: MWITHIGA GIKURU , JINDAL V.K.
Published: February 2007

Parchment coffee (Arabica) was dried from an initial moisture content of about 90% to 10% dry basis (db) in a recirculating rotary conduction type heating unit at controlled plenum temperatures of 100, 120 and 140C or controlled product temperatures of 50, 60, and 70C. the temperature of the plenum or moving beans could be maintained at specified levels with small variations during coffee drying experiments. the color and specific gravity of coffee beans exhibited minimum changes as a result of drying operations. the susceptibility of coffee beans to breakage decreased with the lowering of moisture and attained minimum values in the moisture content range of 20 to 30% db. the breakage susceptibility increased sharply with further reduction in moisture content. A drying model, which considered product temperature‐time history alone under different operating conditions, estimated the change in moisture content adequately. Such a model could be used for computer‐based control of the coffee drying process.
OPTIMIZATION of A CUPUAÇU (THEOBROMA GRANDIFLORUM) NECTAR FORMULATION
Authors: VIEIRA MARGARIDA C. , SILVA CRISTINA L.M.
Published: February 2007

A Cupuaçu (Theobroma grandiflorum) nectar formulation was optimized, for European consumers, using an augmented simplex centroid mixture design. the working ranges, x1(Sugar, 10–25%), x2(Cupuaçu, 15–30%) and x3(Water, 60–75%), were based on a common Brazilian recipe. As responses, a sensory panel evaluated taste, acidity, sweetness, viscosity, mouthfeel and overall opinion. For each response, the best mathematical predictive model was chosen, based on Response Surface statistical analysis. an optimization was then performed, and the optimum was Cupuaçu (18.5%), Sugar (11%) and Water (70.5%). Tolerance tests were carried out and, although differences were detected (α= 5%), the level of acceptance remained above average.
FOOD TEXTURE MEASUREMENTS WITH THE PENETRATION METHOD
Authors: DEMAN J. M.
Published: February 2007

Following the work of Bourne, penetration measurements were performed with two sets of punches. The first set had a constant area and various perimeters. The second set had a constant perimeter and various areas. At constant perimeter, the relationship between punch area and force was a straight line with process cheese, butter and margarine, the latter two going through the origin. At constant area, the relationship between punch perimeter and force was a straight line for process cheese, but no definite relation between punch perimeter and force was obtained with butter and margarine. The relationship between the nature of the curves and the physical structure of the food is discussed. It was concluded that penetration tests of cellular products such as fruits studied by Bourne may involve shear and compression factors. In products with strongly bound network structures, e.g. process cheese, the main factors are shear and flow. In products with weakly bound network structures, such as plastic fats, flow is the only major factor involved.
RECENT ADVANCES IN PHARMACEUTICAL RHEOLOGY
Authors: BARRY B. W.
Published: February 2007

Significant advances in rheology of pharmaceutical and allied materials since 1965 are covered in a review of 292 references. The subject matter is divided into considerations of powders, suspensions and suspending agents, semi‐solids (creams and ointments), emulsions, suppositories and pessaries, foam aerosols and a general section. Material related to tablets, biorheology, and surface and interfacial films is not considered.
CONSUMER AWARENESS OF TEXTURE AND OF OTHER FOOD ATTRIBUTES, II
Authors: SZCZESNIAK ALINA SURMACKA
Published: February 2007

Abstract. A word association test given to one hundred and fifty respondents drawn from three geographic locations and representing a sample balanced with respect to socio‐economic class, sex, and age confirmed the results of a previous test (Food Technol. 27, 74, 1963) conducted with one hundred General Foods employees. Frequency of free associations indicated that texture is a discernible characteristic of foods and that, in general, its awareness equals that of flavor. Women and people in higher economic brackets showed a higher degree of texture awareness.
RELATIONSHIP BETWEEN SENSORY ASSESSMENT AND RHEOLOGICAL PROPERTIES OF COSMETIC CREAMS*
Authors: SUZUKI KAZUSHIGE , WATANABE TAKEHIKO
Published: February 2007

One hundred and forty‐four untrained judges ranked O/W creams on consistency, spreadability, and stickiness or tackiness, and the results were correlated with rheological characteristics obtained from flow curves. The ranking order for consistency corresponded, for all practical purposes, to the ranking order for shear stress needed to break down the internal structure of the sample (shear rates of 44 s‐1 or less). The ranking for spreadability was related to plastic viscosity at 26–32°C. The judges showed poor agreement on the ranking for stickiness (tackiness) and no clear‐cut relationship could be obtained between this property and rheological parameters. Consumer preference favored the sample with the highest consistency.
MEASUREMENT OF TEXTURAL PROPERTIES OF FOODS WITH A CONSTANT SPEED CONE PENETROMETER
Authors: TANAKA M. , DE MAN J. M. , VOISEY P. W.
Published: February 2007

Abstract A constant speed cone penetrometer was used to measure textural properties of a variety of foods. Apparent viscosity and yield value were calculated from the recorded relationships of penetrating force and depth. Good agreement was found between yield values determined by this method and those obtained with a constant weight cone penetrometer.
PREDICTING MEAT TENDERNESS FROM MUSCLE TENSILE PROPERTIES
Authors: STANLEY D. W. , McKNIGHT L. M. , HINES W. G. S. , USBORNE W. R. , DEMAN J. M.
Published: February 2007

Two major types of objective measurements were performed on raw porcine psoas muscle (I ‐ shearing and breaking strength tests; II ‐ sarcomere length, elasticity, stress relaxation and break elongation) and compared with taste panel evaluation (tenderness, elasticity, and chew count) of cooked meat. A standard sample of texturized vegetable protein used as a reference by the panel proved useful in reducing variations between the chew count test and the objective evaluation; it was not of significant value with the other sensory evaluations.

No significant correlations were found between the two groups of objective measurements. Breaking strengths of small longitudinal strips of tissue, following a brief cyclic or extension stretching on the Instron, were the best predictors of sensory tenderness accounting for 59–90% of variation. Other measurements also gave significant correlations.

The major source of variation in breaking strength values was the variation between animals, but the post‐mortem treatment (restraining versus not restraining during rigor) and the interaction between animals and the post‐mortem treatment also were significant in some cases. Breaking strengths of uncooked samples from the same muscle showed a coefficient of variation of up to 54%. It is concluded that there are two major structural contributions of raw muscle to cooked meat tenderness, a connective tissue factor and a contraction factor; different objective methods are best suited for their evaluation.
SWEETNESS PERCEPTION IN RELATION TO SOME TEXTURAL CHARACTERISTICS OF HYDROCOLLOID GELS
Authors: MARSHALL SUSAN G. , VAISEY MARION
Published: February 2007

The apparent sweetness of five different hydrocolloid gels prepared with equal amounts of sodium Sucaryl varied significantly (P < 0.01) when tested in a multiple paired arrangement by seven trained judges. Results from four replications consistently showed sweetness to be the greatest in carrageenan gels and the least in cornstarch gels. It was intermediate in low methoxyl pectin, agar and gelatin gels. Concentrations of gelling agents were selected to produce gels comparable in hardness. Characterization of mechanical textural properties with the GF‐Zenken Texturometer showed that gels of cornstarch and gelatin were more cohesive, springy, chewy and gummy than those of agar, low methoxyl pectin and carrageenan (P < 0.01). These findings suggested that gels which take more effort to disintegrate limit taste perception. Multiple regression analyses showed that the measured mechanical textural parameters accounted for 52.3% of the variability in sweetness scores suggesting that other characteristics may also play a role. Inspection of correlation coefficients of sweetness with single textural parameters showed no one characteristic as a dominating influence over sweetness.
INFLUENCE OF GEL NETWORKS IN CONTROLLING CONSISTENCY OF O/W EMULSIONS STABILISED BY MIXED EMULSIFIERS
Authors: BARRY B. W. , ECCLESTON G. M.
Published: February 2007

A coherent explanation is presented of the mechanisms by which mixed emulsifiers of the surfactant/fatty alcohol type both stabilise and control the consistencies of oil‐in‐water emulsions. Original and published data are used to develop a theory in which the semisolid and other flow properties of emulsions are related to the nature, strength and extent of viscoelastic networks present in the continuous phases. These networks form from the interaction of surfactant solution with fatty alcohol and have similar properties to ternary system gels formed when the mixed emulsifiers disperse in water, in the absence of an oil.

The theory is discussed with particular reference to liquid paraffin‐in‐water emulsions prepared with the surfactants anionic sodium dodecyl sulphate, cationic alkyltrimethylammonium bromides or non‐ionic cetomacrogol and fatty alcohols cetyl and stearyl and their mixtures, especially cetostearyl. It may be used also to explain the properties of emulsions prepared with a variety of oils, surfactants and amphiphiles. The effects of variation in storage time, surfactant type (ionic or non‐ionic), temperature, mixed emulsifier concentration, and alcohol and surfactant chain lengths on the rheological and microscopical properties of ternary systems and emulsions support this theory. The importance of small strain experiments (creep and oscillatory) in providing a true measure of consistency is emphasized. Continuous shear experiments, although theoretically less satisfactory, provide useful additional information when correlated with the small strain data.
IDENTIFICATION OF STIMULI CONTROLLING THE SENSORY EVALUATION OF VISCOSITY I. Non‐Oral Methods
Authors: SHAMA F. , PARKINSON C. , SHERMAN P.
Published: February 2007

Flow properties of several liquid and semi‐solid foods were characterized objectively with a coaxial cylinder viscometer. At the same time, a sensory evaluation panel compared the viscosities of these samples by tilting the containers and also by stirring the contents with a spoon. Correlation of the instrumental and sensory evaluation data established the shear stress‐shear rate conditions prevailing during sensory evaluation of viscosity. The stimulus responsible for viscosity evaluation by tilting the container is the shear rate (0.1–40 sec‐1) developed at a shear stress (60–600 dyne cm‐2) related to the flow properties of the sample, whereas in stirring tests the stimulus is the shear stress (102–104 dyne cm‐2) developed at a particular rate of shear (90–100 sec‐1). In the latter type of test, the shear rate varies to some degree with the flow characteristics of the sample. Since different stimuli are involved in viscosity assessment by tilting the container or by stirring, it is possible for a series of samples to be given different ranking orders by the two methods of evaluation.
STRESS RELAXATION DURING FORCE‐COMPRESSION STUDIES ON FOODS WITH THE INSTRON UNIVERSAL TESTING MACHINE AND ITS IMPLICATIONS
Authors: SHAMA F. , SHERMAN P.
Published: February 2007

Abstract. The time required to apply the force in force‐compression studies with the Instron Universal Testing Machine is long enough for short time relaxation processes to operate, possibly via intermolecular attraction forces. A theoretical analysis is presented whereby stress relaxation can be determined for the stress‐strain region in which the Boltzmann Superposition Principle is valid. Application of the analysis is demonstrated using force‐compression data obtained on cheeses of different textural properties. After correction for stress relaxation, the calculated and experimental relaxation modulus‐time curves agree satisfactorily over a much longer time interval for Edam cheese than for Cheddar cheese. The latter cheese becomes non‐linear at much smaller compressions than does Edam cheese, possibly by the propagation of cracks through the sample during compression. Firmness is one of the textural properties evaluated during the first bite of mastication. Since the time associated with the first bite is longer than that required for application of force during the first compression of a sample with the Instron in this study, it is possible that the sensory evaluation of firmness is made under conditions involving stress relaxation.
THE USE OF SENSORY AND INSTRUMENTAL ASSESSMENT OF ORGANOLEPTIC CHARACTERISTICS VIA MULTIVARIATE STATISTICAL METHODS
Authors: LEVITT D. J.
Published: February 2007

The need to select relevant sensory and instrumental variables is discussed and illustrated by an example concerned with the textural characteristics of a gel system. Discriminant analysis is used to identify the important sensory and instrumental variables and multiple regression to verify that the instrumental variables contain the required information. The limitations of this approach and possible modifications to deal with particular problems are also discussed. The approach described has proved successful in a number of applications
GENERAL FOODS TEXTUROMETER APPLICATION TO FOOD TEXTURE RESEARCH IN JAPAN
Authors: TANAKA MINAKO
Published: February 2007

Applications of the General Foods Texturometer to food research in Japan are reviewed based mainly on information published in Japanese scientific journals. The instrument is being used on various food items such as rice, fish, soybeans, gels, meat, cheese and spaghetti. Correlations with sensory evaluation, development of a similar apparatus for crispness characterization of vegetables and new interpretation of Texturometer parameters are also discussed.
THE EFFECT OF TEMPERATURE ON SOME RHEOLOGICAL PROPERTIES OF WHEAT FLOUR DOUGHS
Authors: BLOKSMA A. H. , NIEMAN W.
Published: February 2007

Abstract. Doughs from three flours were sheared between a cone and plate at constant rates in the range 6 times 10‐4‐2 times 10‐2 s‐1.

At temperatures between 25 and 40d̀C, the apparent viscosity decreased with increasing temperature and with increasing rate of shear. The effects of the temperature and of the rate of shear were independent one of another, and can be described by an Arrhenius type equation and a power equation, respectively. At temperatures between 45 and 60d̀C, the apparent viscosity increased rapidly with increasing temperature; this is ascribed to starch gelatinization. In this temperature range, the apparent viscosity decreased more rapidly with increasing rate of shear than at lower temperatures.

At temperatures between 25 and 45d̀C, the shear modulus decreased with increasing temperature and slightly increased with increasing rate of shear. From the former fact it is concluded that the elasticity of dough has an origin different from rubber elasticity. In this temperature range, the shear modulus can be described by an equation similar to that for the apparent viscosity. At temperatures between 45 and 65d̀C, the modulus increased with increasing temperature, though to a lesser extent than the apparent viscosity.

Changes in the rate of stress relaxation are in accordance with the effects of temperature and rate of shear on the apparent viscosity and the modulus.
RHEOLOGICAL PROPERTIES OF PECTATE GELS
Authors: MITCHELL J. R. , BLANSHARD J. M. V.
Published: February 2007

Creep compliance measurements were made on calcium pectate gels using a paralled plate viscoelasto‐meter. Linear viscoelastic behaviour was observed and the response was consistent with a model containing a Maxwell element in series with three Voigt elements. When gels were prepared with the calcium level necessary for maximum gel strength a linear relationship was found between the reciprocal of the creep compliance and the square of the polysaccharide concentration.

The rheological behaviour of pectate gels had many similarities to gels prepared from alginates containing a high proportion of guluronic acid residues. However, pectate gels were more sensitive to calcium ions than alginate gels and at high calcium levels the Newtonian viscosity of the pectate gel was much higher than that found for the alginates. These differences have been interpreted in terms of the structure and molecular weight of the two polymers.
EVALUATION OF GOUDA CHEESE FIRMNESS BY COMPRESSION TESTS
Authors: CULIOLI J. , SHERMAN P.
Published: February 2007

Cheese maturity, test temperature, crosshead speed, sample shape, sample height and surface area influence the force‐compression behaviour of Gouda cheese in an Instron Universal Testing Machine. Introducing mineral oil or Emery paper between the sample's surfaces and the compression plates affects the shape of the compressed samples. Cine‐film records indicate that deformation is barrel‐shaped (convex) with Emery paper and under normal test conditions, and concave with mineral oil. In the first two test situations friction prevents the cheese surfaces from spreading to the same extent during sample compression as when using mineral oil. Compression as modified by friction may be the principal factor associated with the subjective evaluation of firmness by squeezing samples between the fingers. Firmness evaluation by chewing involves still higher percent compressions which, in Instron tests, lead to sample breakdown and crack propagation.
THE FLOW PROPERTIES OF SKIM MILK CONCENTRATES OBTAINED BY ULTRAFILTRATION
Authors: RANDHAHN HORST
Published: February 2007

The flow properties of skim milk concentrates were measured at temperatures ranging between 5 and 60 °C. The concentrates obtained by ultrafiltration showed, in the studied range of shear rate 5 < D < 1000s−1, pseudoplastic behaviour depending on solids content and temperature. This behaviour is well described by the power law. For both the parameter ψ and n of this law there is a clear dependence on solids content and temperature. The viscosity parameter ψ increases highly from a certain solid content. As there exists a relation between the viscosity and the coefficient of diffusion, which is an essential factor of influence on the process of ultraflltration, these well defined results of objective rheological measurements have consequences about the practicability of this process of separation for the enrichment of protein in skim milk.
CONSIDERATIONS OF A GENERAL RHEOLOGICAL MODEL FOR THE MECHANICAL BEHAVIOR OF VISCOELASTIC SOLID FOOD MATERIALS*
Authors: PELEG M.
Published: February 2007

A model describing the rheological behavior patterns of solid foods is suggested and discussed. It consists of a parallel array of a generalized Maxwell body in which the Maxwell elements have been modified by incorporation of two fracture elements. The model enables the anticipation of response patterns of real food materials under various force—deformation histories without becoming inconsistent. It also predicts the viscoelastic phenomena of materials after their failure and does not exclude the elastic deformation stage. The effects of experimental conditions, differences between various types of foods, as well as variations and changes in the same food can be expressed or explained in terms of model components and their relative distribution. The application of the model is demonstrated with a small number of representative elements.
CONTRIBUTIONS OF THE US ARMY NATICK RESEARCH AND DEVELOPMENT CENTER TO THE OBJECTIVE MEASUREMENT OF THE TEXTURAL QUALITY OF MEAT*
Authors: SEGARS RONALD A. , KAPSALIS JOHN G.
Published: February 2007

Several approaches to the problem of objective measurement of the texture of meat, including modification of existing devices and development of new units, are presented. A mathematical‐mechanical model is introduced which shows that some of the simpler tests presently used measure only part of the textural properties of meat; additional tests are needed to improve texture evaluation.
TEXTURE OF FROZEN FRUITS AND VEGETABLES
Authors: BROWN MILFORD S.
Published: February 2007

This review discusses factors responsible for the texture of fruits and vegetables and the changes brought about by freezing. It describes some of the early work on frozen food texture, as well as the more recent studies of cryogenic and other rapid freezing methods. The effects of storage and cooking on texture are also considered.
RHEOLOGY OF LIQUID FOODS ‐ A REVIEW1
Authors: RAO M. A.
Published: February 2007

Liquid foods are classified and their properties discussed under various types of rheological behavior: Newtonian, pseudoplastic, shear thickening, thixotropic, and viscoelastic. Rheological data on selected liquid foods are summarized in either tabular form or in the form of equations. Wherever possible the influence of temperature, constituents, and structure on the rheological behavior is detailed. Because many foods are suspensions, the measurement of flow properties of suspensions and factors influencing their rheological behavior are also covered. Finally, the relationship between the flow behavior and the sensory evaluation of mouth feel and viscosity is discussed.
THE EFFECTS OF LONG TERM COOKING ON SHEAR FORCE‐DEFORMATION CURVES
Authors: BOUTON P. E. , HARRIS P. V. , MACFARLANE J. J. , SNOWDEN J. McK.
Published: February 2007

The influence of muscle contraction, pressure‐heat, and cooking conditions on some parameters of the Warner Bratzler shear force curves were studied.

Stretched meat samples, restrained from shortening along the muscle fibers during cooking for a short time at 90°C, had larger peak shear force values than samples cooked unrestrained. As cooking times were increased, peak shear force values decreased until after 8‐16 hr the cooked restrained samples had lower values than the unrestrained ones. The initial yield force values obtained for pressure‐heat treated samples were not significantly affected by cooking at 90° for up to 32 hr, although the peak shear force values decreased with cooking time. The experimentally determined shear curves were shown to be approximated by summing the estimated individual contributions of the myofibrillar and the connective tissue components. The results are consistent with the suggestion that the initial yield force values represent mainly the myofibrillar strength and that the difference between the peak force and the initial yield force represents the contribution of the connective tissue.
COMPRESSION RATES IN THE MOUTH
Authors: BOURNE MALCOLM C.
Published: February 2007

The mte of compression of solid foods in the mouth varies widely. The rate of movement of the jaws is not linear but follows an approximate sine curve pattern. The first few chews on a piece of food are frequehtly slower than subsequent chews. Other factors that affect the mte of compression are: differences in chewing mtes between individuals, how wide the jaw is opened, the placement of teeth with respect to the temperomandibular joint and the type of food. More studies are needed on compression mtes between the teeth in order to establish the mnge of compression speeds that would be preferred for use in objective texture measurements.
USE OF RHEOLOGICAL TERMS AND CORRELATION OF COMPATIBLE MEASUREMENTS IN FOOD TEXTURE RESEARCH1
Authors: MOHSENIN NURI N. , MITTAL J. P.
Published: February 2007

The importance of maintaining the purity of rheological terms and using them only when measurements and definitions are in accordance with the accepted rheological definitions is pointed out. It is shown that if rheological terms and methods of measurements and analyses are used correctly, they can be employed in food texture studies even though conditions upon which the theory is based are not fully met. It is proposed that the term “modulus of elasticity” be replaced by the term “modulus of deformabtiity” which considers both recoverable and unrecoverable deformations that often take place when a food sample is subjected to even very small strains. It is also submitted that mechanical properties reflecting the behavior of the material under small strains do not necessarily correlate significantly with mechanical properties which reflect the yielding and fracturing or failure of the material. Published data are examined to test the validity of this hypothesis. In general, correlations between well‐defined failure type instrumental tests and panel tests are good, whereas correlations between small‐strain instrumental tests and panel tests are poor.
EFFECT OF HYDROCOLLOIDS ON APPARENT VISCOSITY AND SENSORY PROPERTIES OF SELECTED BEVERAGES1
Authors: PANGBORN ROSE MARIE , GIBBS ZIAIEH MISAGHI , TASSAN CATHERINE
Published: February 2007

The effects were studied of low concentrations of 5 selected hydrocolloids (xanthan, hydroxypropylcellulose, sodium alginate, and carboxymethylcellulose of low and medium viscosity types) on viscosity and sensory properties of 3 commercial beverages: tomato juice, orange drink and soluble coffee. Tomato juice and orange drink were tested at 0° and 22°C, while coffee was tested at 22° and 60°C by 11‐14 highly trained judges. Apparent physical viscosity was determined with a Brookfield uiscometer. Due to precipitate formation, it was not possible to test sodium alginate in orange drink nor hydroxypropylcellulose in coffee at 60°C.

Without exception, increasing the hydrocolloid concentration significantly depressed (P < 0.001) the flavor and aroma intensities of all beverages a t both test temperatures. Taste effects were specific for the gumlbeverage combinations. In general, gums depressed the sourness and saltiness of tomato juice, the sourness of orange drink and the bitterness of coffee.

Both physical and oral viscosities increased with gum concentration and decreased with temperature. Positive synergism was displayed by gums in tomato juice and orange drink. Excellent correlations (r > 0.9) were obtained between sensory and physical viscosities.
FORCE‐DEFORMATION CONDITIONS ASSOCIATED WITH THE EVALUATION OF BRITTLENESS AND CRISPNESS IN SELECTED FOODS1
Authors: SHERMAN P. , DEGHAIDY F. S.
Published: February 2007

The brittleness and crispness of low moisture foods and the crispness of selected high moisture foods were evaluated both instrumentally by Instron fracture tests and using a sensory panel. Brittleness was evaluated sensorially during the “first bite” whereas crispness was identified at a later stage of mastication. The maximum force at fracture of low moisture foods correlated inversely with panelists’ evaluations of brittleness either in the mouth or using the fingers. Panelists' evaluations of crispness in the mouth correlated reasonably well with the initial linear portion of the Instron force‐deformation curves when the sample were supported near their ends and also in their middle regions. The shapes of the force‐deformation curves for high moisture foods were very much influenced by the way in which samples were supported in fracture tests, the method of fracture and the Instron cross‐head speed.
PHYSICO‐CHEMICAL ASPECTS OF SOY PROTEINS STRUCTURE FORMATION
Authors: HERMANSSON A. M.
Published: February 2007

Mechanisms involved in the formation of three‐dimensional networks of globular proteins are discussed in general terms. Denaturation and aggregation of soy proteins under various conditions were studied. Differential scanning calorimetry was used in the denaturation, and turbidity measurements in the aggregation studies. Conditions favoring denaturation, such as high and low pH, had the opposite effect on aggregation. Salt was found to have a special effect on the behavior of soy proteins, suppressing aggregation as well as denaturation, probably due to its stabilizing influence on the quaternary structure. Viscometric studies of the progel state of soy protein gels showed that the onset of the progel is closely related to the denaturation process. Some commercial isolates were found to be completely denatured. Despite forming firm gels after cooling, they did not appear to have a progel state.
A REVIEW OF THE PHYSICOCHEMICAL APPROACH TO THE ANALYSIS OF THE STRUCTURAL VISCOSITY OF FLUID FRUIT PRODUCTS
Authors: MIZRAHI S.
Published: February 2007

The main goal of the physicochemical approach is to understand the flow mechanism in fluid fruit products and to control as well as “synthesize” a desired consistency. Three methods have been employed in an attempt to correlate the rheological parameters of the product with the physicochemical properties of its components.

The first method uses flow and physicochemical data, obtained from samples where a single factor is varied at a time, to derive an empirical correlation. This correlation is subsequently verified on commercial samples before putting it into practical use.

The second method is based on an analogy between a well analysed experimental model and a closely related commercial product.

The third method is based on a theoretical model. Since to‐date there are no specific models for fluid fruit products, use was made of a modification of Casson's equation which yielded satisfactory results for orange juice concentrate.
EFFECT OF HEATING RATE ON VISCOSITY OF WHEAT FLOUR DOUGHS1
Authors: BLOKSMA A. H.
Published: February 2007

Doughs were sheared at a constant rate and heated in a cone‐and‐plate viscometer. As the temperature increased, the apparent viscosity first decreased, passed a minimum, and then increased rapidly presumably due to the swelling of starch granules. If the dough was heated more rapidly, the viscosity had its minimum value at a higher temperature. This is explained by the swelling of starch granules being a rate process. The present experiments explain why in previous work with heating prior to shearing, the minima in the viscosity versus temperature curves were found at unexpectedly low temperatures. The temperature at which in a standard amylograph experiment the viscosity begins to rise is a fairly good estimate of the temperature at which viscosity has its minimum value during baking. The agreement is due to compensating effects of the rate of heating and of the starch concentration.
RHEOLOGICAL PROPERTIES OF HYDROCOLLOIDS IN THE PRESENCE OF SUCROSE AND MILK
Authors: ELFAK A. M. , PASS G. , PHILLIPS G. O.
Published: February 2007

Apparent viscosities of guar gum, locust bean gum, and sodium carboxymethylcellulose were measured at shear rates of 16‐2620s‐1 in water, sucrose, milk, and sucrose/milk solutions. The effect of different heat treatments was also studied. For all solutions, a power law equation described the variation of relative viscosity with shear rate allowing comparison of their non‐Newtonian behaviour. With the neutral hydrocolloids, the hydration was limited by the presence of sucrose and milk which reduced the effective length of the polymer molecules. The behaviour of the polyanionic hydrocolloid, Na CMC, although influenced by milk and sucrose separately, was controlled by milk in a milk/sucrose mixture. This is due to milk salts which reduced the intramolecular repulsions along the polyanion and substantially lowered its effective hydrated length.
TEXTURE OF FISH MUSCLE
Authors: DUNAJSKI E.
Published: February 2007

Morphological and chemical aspects of fish muscle texture are reviewed and differences from red meat are pointed out. A unique feature of fish muscle is its low connective tissue content which accounts for easy disintegration of fish flesh on heating. Thus, the muscle fibers are the main textural elements in cooked fish meat. Because of this, most of the popular texture testing instruments are not applicable to fish. Best results are obtained with the thin blade shear/compression cell.

Texture of fish muscle is affected by the species, age and size of the fish within the species, and nutritional state. Postmortem factors influencing texture include glycolysis, rigor mortis and the accompanying contraction of the muscle often leading to the separation of muscle segments (gaping), temperature profile during storage, temperature of cooking, pH and presence of NaCl.
USE OF THE CONE PENETROMETER FOR TESTING THE FIRMNESS OF BUTTER
Authors: DIXON B. D. , PAREKH J. V.
Published: February 2007

Analysis was made of cone penetration test parameters for butters of a wide range of firmness. The relationship:

accounted for 96.9% of the variation in the observations. This relationship, which has the dimensions of stress, differs from the previously proposed rheological models. An index, based on this relationship, was found to account for approximately 91% of the variation in the sensorially perceived spreadability of the butters.
A GENERALIZED PHENOMENOLOGICAL RHEOLOGICAL MODEL FOR FISH FLESH
Authors: JOHNSON E. A. , PELEG M. , SEGARS R. A. , KAPSALIS J. G.
Published: February 2007

The mechanical properties of raw and cooked fish were qualitatively characterized by a generalized Maxwell model in which each of the Maxwell elements is modified by incorporation of a contact and two fracture elements. The activation and inactivation of elements have been used as a means of expressing transformation of the rheological characteristics, not only as a function of the strain and strain rate history but also as a function of temperature and time. Although no attempt has been made to quantify the number of elements and their characteristic constants, it is shown that the different modes of rheological behavior exhibited by fish flesh can consistently be described by this kind of model.
THE THERMAL FRACTURABILITY LOSS OF EDIBLE PLANT TISSUE: PATTERN AND WITHIN‐SPECIES VARIATION1
Authors: LOH J. , BREENE W. M.
Published: February 2007

The pattern of fracturability loss of 11 selected fruits and vegetables during thermal processing was studied. In general, the first‐order kinetic model is adequate in describing such changes during heating of edible plant tissue before reaching equilibrium texture. However, textural changes are less predictable by the first‐order kinetic model in tissues having thick cell walls (such as those derived from stems and roots) than in tissues having thin cell walls (such as those derived from fruits).

For a given species (potato), the first‐order model can be applied regardless of sample dimension, morphological origin of the sample, heating temperature, variety, prior storage conditions, maturity and minor agronomic variation.