摘要:

Eighteen experienced judges evaluated the texture of gels varying in gelatin concentration (22‐45 g/L) in terms of firmness by oral and manual shear and compression, cohesiveness, and extent of breakdown in the mouth. Manual compression and biting with the front teeth discriminated well across gel concentrations. All sensory measures except extent of breakdown increased with gelatin concentration. Instron (IUTM) measurements showed that increasing gelatin concentration resulted in an increase in maximum force and force/deformation, but had little effect on deformation at yield and rupture or in elasticity and cohesiveness. Results from mechanical measurements varied with the type of force applied (compression, shear or puncture), the loading rate (50 or 200 mm/min), and the extent of deformation attained (40–90%). The highest discrimination across gel concentrations was achieved with shear force at a rate of 200 mm/min and at greater deformations. Sensory responses correlated most highly with the following IUTM measurements: (1) Compression forces at yield and at deformations of 70 and 85% at the higher crosshead speed; (2) Compression forces below the yield point at the lower crosshead speed; and (3) Shear forces measured at maximum deformation (90%) at 200 mm/

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1986.tb00710.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Sensory texture attributes of firmness (manual, oral, shear and compression), elasticity and type of breakdown of gelatin, sodium alginate, and kappa‐carrageenan gels at two concentrations, were evaluated by 18 experienced judges. Nine of the judges also evaluated oral temporal responses to firmness and sourness. The Instron Universal Testing Machine (IUTM) was utilized to measure compression and shear at 200 mm/min at varying deformations. Gelatin was the firmest and most elastic of the three gels. During mastication it broke down into a few large pieces. Carrageenan produced the least firm and least elastic gel which failed into a large number of small pieces. Time‐intensity recordings demonstrated that more oral manipulation time was required to break down carrageenan and alginate gels in contrast to thermally‐degradable gelatin gel. Whereas perceived oral firmness reached a maximum in less than 5 s after placement of a gel sample in the mouth, maximum sourness was not perceived until 13‐18 s. Greater discrimination between gel concentrations was obtained by sensory than by mechanical measures, and beyond rather than below the yield point. Estimates of sensory firmness by shearing were highly correlated with each other and with mechanical shear and compression force. Manual compression correlated only with surface rupture force, while oral compression correlated only with shear maximu

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1986.tb00711.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Instrumental methods to analyze texture of plain chocolates and milk chocolate are reviewed. Using a strength testing apparatus and special measuring cells a method to determine the compression strength, shear strength and rupture force during hesion testing are described. By means of a modified penetrometer equipped with a recording device the melting properties were determined. To determine the maximum value of size of disperse components a modified precision thickness testing instrument is applied. The methods offer good reproducibility. The influence of some measuring parameters and sources of error are explained.

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1986.tb00712.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

The effects of twin screw extrusion cooking of maize grits at different high moisture contents are described. Starch granules survive in the extrudate at high extrusion moisture or with a low shear screw configuration. The aqueous dispersion rheology of the milled extrudate and its dependence on shear rate and heat treatment is explained in terms of the starch swelling behaviour and solubility. These data resemble that of raw maize most closely for the low shear screw configuration. For the high shear configuration under similar conditions of moisture, temperature and mechanical energy dissipation, starch granules are not seen and the dispersion rheology is markedly different from that of raw maize.

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1986.tb00713.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

The viscosity of pure and mixed dilute solutions of commercial alginate, carrageenan, guar gum, CMC and gelatin solutions at different mixing ratios were measured by a coaxial viscosimeter at different shear rates. The results are presented in the form of measured viscosity divided by the expected viscosity, if no interaction between the gums existed. This technique provides a clear demonstration of the existence of synergism or antagonism between the gums and helps in quantitatively assessing their extent.

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1986.tb00714.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Starch‐thickened, strained apricots were found to exhibit irreversible thixotropy. Shear stress and shear rate were estimated from mixer viscometer data. A structural parameter, yield stress, flow behavior index and a consistency coefficient were determined to quantify the rate of breakdown and equilibrium structure of the product. The techniques developed in this study are useful in describing the time‐dependent behavior of suspensions because the slip at the wall is minimi

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1986.tb00715.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

The Voland‐Stevens LFRA texture analyzer was compared to the Tarr‐Baker gelometer for its applicability to measuring jelly strength. Both instruments showed a linear relationship between jelly break strength and pectin content. The test results from the two instruments were highly correlated (r = 0.94). The coefficient of variation relative to the overall average of measurement was 5.0% for the Voland‐Stevens LFRA and 8.4% for the Tarr‐Baker gelometer. The Voland‐Stevens LFRA instrument may be equal to or better than the Tarr‐Baker gelometer for measuring jelly break strength. It offers the advantages of reduced errors in sample preparation and ease of instrument

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1986.tb00716.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Immunoassays in Food Analysis.B. A. Morris and M. N. Clifford (eds.) Elsevier Applied Science Publishers, New York. 248 pp. $37.50.

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1986.tb00717.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

GENERAL PRINCIPLES The Voluminosity of Casein Micelles.T. H. M. Snoeren, H. T. Klok, A. C. M. Van Hooydonk and A. J. JammanINSTRUMENTATION&METHODOLOGY: A New Viscoelastometer for Studying the Rheological Properties of Bronchial Mucus in Clinical Practice.C. Duvivier, J. Didelon, J. P. Arnould, J. M. Zahm, E. Puchelle, C. Kopp and B. ObrechtINSTRUMENTATION&METHODOLOGY: A Laboratory Assembled Simple Apparatus for Objective Measurements of Mechanical Parameters of Foods.S. A. Moturi, K. Kubota, K. Suzuki and M. EsakaINSTRUMENTATION&METHODOLOGY: Viscosity Evaluation of Drum Contents by Torsional Vibration.S. Wu, L. F, Whitney and M. PelegINSTRUMENTATION&METHODOLOGY: Texture and Mechanical Properties of Pork Backfat.E. Dransfield and R. C. D. JonesINSTRUMENTATION&METHODOLOGY: Examination of the Composition and Efficiency of Certain Surface‐Active Additives (CPL and CSL Preparations) Used in the Baking Industry.F. Orsi, A. Abraham‐Szabo and R. LasztityINSTRUMENTATION&METHODOLOGY: A New Apparatus for Measuring the Thread‐Forming Property (Spinability) of Biological Fluids.J. P. Arnould, J. M. Zahm, G. Potter, G. Duvivier and E. PuchelleINSTRUMENTATION&METHODOLOGY: Milk Gel Structure XIV. Fixation of Fat Globules in Whole‐Milk Yoghurt for Electron Microscopy.P. Allan‐Wojtas and M. KalabINSTRUMENTATION&METHODOLOGY: Method for the Study of Changes in the Shear Modulus of Milk Gels at Constant Strain.D. E. JohnstonSUBJECTIVE MEASUREMENTS: Investigation into the Interaction of Different Properties in the Course of Sensory Evaluation. 111. Interaction Between Colour, Texture and Flavour.Gy. UrbanyiFACTORS AFFECTING TEXTURE: Muscle Fibre Orientation and Its Effect on Measurements of Tenderness of Bovine Longissimus Dorsi Muscle.A. C. Murray, L. E. Jeremiah and A. H. MartinFACTORS AFFECTING TEXTURE: Palatability of Meat from Electrically Stimulated Carcasses of Yearling and Older Entire‐Male and Female Sheep.A. H. Kirton, R. J. Winger, J. L. Dobbie and D. M. DuganzichFACTORS AFFECTING TEXTURE: Study of the Mechanical Properties of Apple with Special Regard to Juice Extraction.K. Vukov, Gy. Patkai, J. Monszpart‐Senyi, J. Hamori‐Szabo and P. MohacsyFACTORS AFFECTING TEXTURE: Aplication of Polymer Cross‐Linking Theory To Rennet‐Induced Milk Gels.D. E. JohnstonFACTORS AFFECTING TEXTURE: Improvement of the Composition and the Texture of the Traditional African Meal “Foufou” by Addition of Monoglycerides to Casava.T. H. Phan and C. MercierFACTORS AFFECTING TEXTURE: Protein Gels in Relation to Their Rheological Properties.T. Sone, s. Dosako and T. KimuraFACTORS AFFECTING TEXTURE: Chocolate Tempering Control By Simplified Differential Thermal Analysis.H. Adenier, H. Chaveron and M. OllivonRELATIONSHIP TO STRUCTURE: Light Microscopy Preparation Techniques for Starch and Lipid Containing Snack Foods.F. O. FlintRELATIONSHIP TO STRUCTURE: Freeze‐Etch of Emulsified Cake Batters During Baking.J. D. Cloke, J. Gordon and E. A. DavisRELATIONSHIP TO STRUCTURE: Aspects of Sample Preparation for Freeze‐Fracture/Freeze‐Etch Studies of Proteins and Lipids in Food Ssytems. A Review.W. BuchheimRELATIONSHIP TO STRUCTURE: Microscopy in the Study of Fats and Emulsions.J. M. deManRELATIONSHIP TO STRUCTURE: Morphological and Textural Comparisons of Soybean Mozzarella Cheese Analogs Prepared with Different Hydrocolloid

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1986.tb00718.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY