摘要:

Cooked pastes of rice flour showed time‐dependent shear thinning (thixotropy). Yield stresses were observed at high concentrations and high pasting temperatures. The Herschel‐Bulkley power law equation could be used with certain limitations to characterize the flow behaviour of the pastes. At low pasting temperatures (60°, 75°C), apparent viscosity increased with increasing concentration and time of cooking, and was higher for low‐amylose than for high‐amylose rice. But when cooked at 95°C, two distinct patterns were seen. At low concentrations, apparent viscosity again increased with increasing time of cooking and was higher for low‐amylose than for high‐amylose rice. But at concentrations above 7%, the pattern was totally reversed, viz., viscosity decreased with time of cooking and was higher for hig

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1989.tb00427.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

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

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1989.tb00428.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Texture characteristics of solidified plain chocolate and milk chocolate were determined in instrumental and sensory studies. The instrumental parameters included compression strength, melting properties, maximum tensile force during hesion testing and the maximum size of dispersed solid components. To classify the sensory texture impressions into intensity ranges, by using appropriate samples, a reference scale was derived allowing a sensory panel to assign unknown chocolate samples to the respective intensity ranges. Instrumental control of the reference samples ensures satisfactory relations between instrumental and sensory data.

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1989.tb00429.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The rheological behaviour of egg yolk over the temperature range 5° to 60°C was studied and found to fit the power law. For egg yolk of different moisture content it was found that the data gave a better fit to the power law than to an exponential equatio

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1989.tb00430.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

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‐1for 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 co

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1989.tb00431.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

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

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1989.tb00432.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Foods containing particles in a matrix were modelled by setting glass spheres, varying in size and surface chemistry, and oil droplets in heat‐denatured whey protein gels. Composites containing particles with hydrophilic surfaces were much stronger in compression, the strength being dependent on particle surface area, than those with hydrophobia surfaces. The relationship between strength and particle size was compared with existing rheological and composite theories. SEM examination of fracture surfaces, resulting from compression, showed that particles with an hydrophilic surface were an integral part of the composite, failure occurring within the protein matrix. Gels made from particles with an hydrophobic surface fractured adjacent to the particle surface, indicating little or no interaction between particle and matri

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1989.tb00433.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The rheological and gelation properties of poultry dark and white meat batters prepared with average and reduced NaCl levels (2%, 1% and 0%) and with 0.5% hexametaphosphate (HMP) added to the 1% salt batters were studied. Lowering the salt content decreased the shear stress in both the white and dark meat at the same shear rates. HMP addition to the 1% NaCl treatments increased the shear stress in the dark meat but not in the white meat at the same shear rates using a concentric cylinder viscometer. The relationship between the rotor angular velocity and shear stress of the raw batters was nonlinear and resembled a pseudoplastic behaviour with yield stress in all cases. Plots of the modulus of rigidity (G) versus cooking temperature indicated that white meat always exhibited higher G than that of dark meat. The highest G was observed in the white meat with 2.0% NaCl and the lowest in the dark meat with no salt. The batters with no salt also exhibited gel formation, however with lower G values.

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1989.tb00434.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

A new method based on computerized image analysis was developed to objectively evaluate the texture of extruded biscuits. The methodology to process the visual image of the transverse cut of biscuit is presented. Structural parameters related to individual cells and the overall biscuit, are determined and discussed to discriminate between various extrudates.

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1989.tb00435.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The consistency index and the flow behavior index of the power law model, and yield stress according to the Casson model that describe the viscoelastic nature of a model salad dressing were determined as a function of storage time and temperature. A four parameter model was employed to describe the creep‐compliance data. Major changes in the magnitudes of the rheological parameters took place during the initial seven days of storage. The changes are attributed to coalescence of oil droplets and to hydration of the food gum. Creep‐compliance data on six commercial salad dressings showed significant differences in the rheological behavior among the dressi

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1989.tb00436.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY