摘要:

ABSTRACTBrittle and crunchy foods are notorious for their irregular and irreproducible force‐deformation relationships which cannot be converted to stress‐strain relationships because of geometric considerations. However, a fairly consistent assessment of their stiffness can still be extracted from their jagged force‐deformation curves. For example, either the averaged force at a given deformation (e.g., 20%), determined directly or calculated by fitting the curves of several specimens with a polynomial model, can be considered a legitimate stiffness measure albeit a relative one. But since the magnitude of such parameters is affected by occasional force lows and minima as well as failure and sliding events at preceding deformations, they can only provide a low estimate of the material actual stiffness. Application of an algorithm that identifies the peak forces in the force‐deformation relationship produces a new relationship that has a fairly regular and much smoother shape. Derivation of stiffness parameters from such curves is not only easier because of the regular shape and reduced number of points but also provides a closer estimate of the material actual st

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1995.tb00977.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACTThe mechanical features of a partially denatured commercial soy isolate (PP 500E) have been explored for comparison with data available on the gelation characteristics of native globular proteins and to improve the understanding of its textural properties as a structuring ingredient in the production of low fat products. The soy sample was reconstituted at 30C and networks were developed either during cooling to 5C or on heating to 90C (complete denaturation of the protein) followed by cooling to 5C. Throughout the course of experimentation, dynamic oscillatory (time, temperature, frequency and strain sweeps) and creep testing (in aqueous or urea solutions) measurements were recorded. Reduction in the thermal energy of the system causes a monotonic increase in storage modulus (G′) whereas the temperature rise results in equilibrium G′ values well below the elastic response observed at 30C. The absence of a positive thermal transition, observed in the gelation of native globular proteins, indicates a different mechanism for structure formation in commercial soy isolates. Application of the cascade treatment to the concentration dependence of the storage modulus argues that the heated and cooled networks possess a higher degree of bond permanency than their cooled‐only counterparts. Mechanical spectra in combination with the pattern of network breakage at high deformations suggests that disulphide bonds participate in the network formed by totally denatured soy protein (heated and cooled samples). Inclusion of urea in the aqueous preparations destabilises the predominantly physical forces of attraction in the unheated gels. By contrast, the heated and cooled samples achieve an equilibrium deformation whose storage modulus can be employed in the constitutive equation of rubber elasticity theory. On that basis the number of disulphide bridges per molecule was found to vary between 2.0 and 2.03. This result is consistent with the “string of beads” model proposed for the three‐dimensional structure of globular protein gels, where a dendric network is built by the occasional cross‐linking of corpus

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1995.tb00978.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACTRecent experimental and theoretical developments in the rheological characterisation of gels are introduced. The basic features of chemical, where crosslinking is covalent, and physical gels, which contain noncovalent crosslinks are outlined, and the kinetics of the gel formation briefly explained. Small deformation methods for characterising gels particularly oscillatory rheometry are considered and the potential of advances in signal processing in particular the use of multi‐wave and Fourier Transform approaches to determine information on the frequency response discussed. The concept of the gel point is discussed and the Winter‐Chambon criterion for defining this from experimental measurements of the frequency dependence of the storage and loss moduli is explai

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1995.tb00979.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACTWe 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 (

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1995.tb00980.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACTThe 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.

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1995.tb00981.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACTLinear and nonlinear viscoelastic properties of food materials are important to product design and process design if they can be quantitatively defined. This paper covers prediction of dilute and concentrated solution, linear viscoelastic properties and models for nonlinear viscoelastic properties. The usefulness of various constitutive models in predicting these properties are discussed and demonstrated.

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1995.tb00982.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACTA range of lemon pie fillings containing the ingredients corn starch, sugar, egg yolk, lemon juice and water were prepared using a constant weight mixture design. There were five ingredients in the system and four ratio variables were employed resulting in 25 formulations. Dynamic rheological and sensory measurements were performed. The latter used magnitude estimation to evaluate the characteristics of thickness, sweetness and lemon flavour. The relationship between the complex viscosity (η*) and perceived thickness was in good agreement with previous work on simpler model systems. Perceived sweetness showed a greater decrease than perceived lemon flavour with increased viscosity. The decrease in sweetness with increasing viscosity increased with increasing sucrose concentration, but was less than has been observed for systems thickened by random coil polysaccharides. An attempt has been made to explain this in terms of solution structure

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1995.tb00983.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

FOOD COLLOIDS AND POLYMERS: STABILITY AND MECHANICAL PROPERTIES.Edited by E. Dickinson and P. WalstraHANDBOOK OF FOOD ADDITIVES.Compiled by Michael and Irene Ash

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1995.tb00984.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

GENERAL PRINCIPLESRheological Behavior and Potential Cross‐Linking of Pacific Whiting Surimi Gel.J.W. Park, J. Yongsawatidgul and T.M. LinFracture of Alaska Pollock Gels in Water: Effects of Minced Muscle Processing and Test Temperature.J.R. Howe, D.D. Hamann (corresponding author), T.C. Lanier and J.W. ParkBreaking Stress and Syneresis of Rennin Curds from Reconstituted Skim Milk Frozen Concentrate.C‐W. Lin, C‐H., Hsieh and H.‐P. SuPhospholipid Hydrosylate and Antistaling Amylase Effects on Retrogradation of Starch in Bread.M.R. Kweon, C.S. Park, J.H. Auh, B.M. Cho, N.S. Yang and K.H. ParkRheological Studies of Water Soluble (1‐3), (1‐4)‐P‐D‐Glucans from Milling Fractions of Oat.K. Wikstrom, L. Lindahl, R. Andersson and E. WesterlundShear Induced Starch Conversion During Extrusion.X. Zheng and S. S. WangModeling Ice Crystal Coarsening in Concentrated Disperse Food Systems.R.L. Sutton, I.D. Evans and J.F. CrillyA Critique of Some Methods Proposed for Evaluating the Emulsifying Capacity and Emulsion Stabilizing Performance of Vegetable Proteins.P. ShermanMETHODOLOGY&INSTRUMENTATIONArnott Test Correlates with Dynamic Rheological Properties for Determining Cheddar Cheese Meltability.Z. Ustunol, K. Kawachi and H. SteffeInstrumental Probe and Method to Measure Stickiness of Cooked Spaghetti and Noodles.F. Guan and P.A. SeibFACTORS AFFECTING TEXTUREThe Influence of Starch on The Rheological Behavior of Micro‐crystalline Cellulose Hydrogels.M. Dolz, F. Gonzalez, M. Herriez and O. Diez‐SalesTextural Properties of Chicken Frankfurters with Added Collagen Fibers.J.‐F. Meullenet, H.C. Chang, J.A. Carpenter and A.V.A. ResurreccionMicrostructural and Rheological Properties of Cooked Squid Mantle.M. Kugino and K. KuginoBlanching, Freezing and Frozen Storage Influence Texture of White Asparagus.M.T. Sanchez‐Pineda‐Infantas, G. Cano‐Miinoz and J.R. Hermida‐BunTexture and Histological Structure of Carrots Frozen at a Programmed Rate and Thawed in an Electrostatic Field.M. Fuchigami, N. Hyakumoto, K. Miyazaki, T. Nomura and J. SasakiFirmness and Cell Wall Characteristics of Pasteurized Jalapeno Pepper Rings Affected by Calcium Chloride and Acetic Acid.L.R. Howard, P. Burma and A.B. WagnerDraw pH and Storage Affect Rheological Properties of Mozzarella Cheese.J.J. Yun, Y.L. Hsieh, D.N. BarbanoRole and Contribution of Starch and Protein Contents and Quality to Texture Profile Analysis of Oriental Noodles.B.X. Baik, Z. Czuchajowska and Y. PomeranzEffect of Decorticated Sorghum Addition on the Rheological Properties of Wheat Tortilla Dough.P.I. Torres, B. Ramirez‐Wong, S.O. Serna‐Saldivar and L.W. RooneyInfluence of 7s and 11s Globulins on the Extrusion Performance of Soy Protein Concentrates.L. Ning and R. VillotaTextural Changes in Vegetables During Thermal Processing I. A Descriptive Method to Segregate Effects of Process Treatments.L.A. Moreira, F.A. Rodrigues Oliveira (corresponding author), J.C. Oliveira and R.P. Singh11. Effects of Acidification and Selected Pretreatments on Texture of Turnips.Microbial and Sensory Characteristics of a Fermented Sausage Extended with Carbohydrate Materials.H. Escalona, E.J. Gallardo, I. Guerrero (corresponding author) and E. PonceEffects of Electrical Stunning Duration on Postmortem Rigor Development and Broiler Breast Meat Tenderness.P.A. Paponaho and D.L. FletcherRelationships Between Muscle Tissue Characteristics and Sensory Quality of Dry‐Cured Ham.S. Buscailhon, C. Touraille, J.P. Girard and G. MoninPhysical and Sensory Properties of Reduced Fat Breakfast Sausage.S. Barbut and G.S. MittalTenderness of Prerigor Stretched Porcine Longissimus Muscle.H. Wang, J.R. Claus (corresponding author) and N.G. MarriottEffects of pH and Salts on the Firmness of Canned Ripe Olives.P. Garcia, M. Brenes and A. GarridoInfluence of Ageing Time, Storage Temperature and Percentage Lean on the Eating Quality of Pork and Its Relationship to Instrumental and Structural Parameters.E. Tornberg (corresponding author), G. von Seth and A. GoranssonAgeing of Beef: Influence of Two Ageing Methods on Sensory Properties and Myofibrillar Proteins.P.H. Heinze and D. BruggemannRheological and Textural Behaviour of Double Cream Cheese. Part I: Effect of Curd Homogenization.C. Sanchez (ENSAIA), J.‐L. Beauregard, M.‐H. Chassagne, J.‐J. Bimbenet and J. HardyRheological and Textural Behaviour of Double Cream Cheese. Part 11: Effect of Curd Cooling Rate.C. Sanchez (ENSAIA), J.‐L. Beaureg

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1995.tb00985.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1995.tb00976.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY