摘要:

The viscoelastic parameters of cowpeas(Vigna unguiculata)were studied at different temperature and moisture content combinations. Cowpeas were tested at temperatures of 25°, 45° and 70°C and moisture contents of 13.9, 19.6 and 22.4% dry basis on an Instron Universal Testing Machine using stress relaxation techniques. The response of cowpeas was characterized by two Maxwell bodies in parallel without the incorporation of a residual spring. The relaxation curves (uniaxial modulus versus time) were used to calculate temperature and moisture shift factors, which subsequently led to the construction of a single master response curve. Cowpeas are both thermo‐rheologically and hydro‐rheologically simple biological mat

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1989.tb00450.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Sensory determination of butter texture properties is usually done with category scales. The present study was undertaken to evaluate the applicability of the magnitude estimation procedure. To obtain individual stimulus‐response‐functions, butter of different temperatures was assessed sensorically for spread‐ability and hardness by means of a trained panel. Instrumental measurements were done with four empirical methods (apparent yield value; extruder; force penetration; sectility). Excellent exponential relationships were achieved between magnitude estimation and instrumental values. Due to individual responses, different constants in the power law equations were found. A second experiment showed that spreadability can be evaluated best by apparent yield value, whereas sensory hardness is imitated by sectility te

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1989.tb00451.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The contribution of seed coat to cooked reconstituted bean texture was assessed by measuring sensory and instrumental parameters of beans with and without coats and also seed coats alone. Experiments using white beans stored for one year under tropical conditions to induce the hard‐to‐cook (HTC) defect or temperate conditions both resulted in reductions in the order of 50% in puncture force and sensory properties of beans when the seed coat had been removed. HTC bean texture was influenced less by absence of the seed coat than texture of soft beans. Seed coats softened during cooking but those from HTC beans softened less than those from soft beans. It is possible that seed coats harden during tropical storage by a lignification‐type mechanism. Beans with harder seed coats absorbed less water during soaking which may contribute further to bean har

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1989.tb00452.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Gluten from the wheat variety Monopol was fractionated by successive extractions with dilute HCl (0.625–1.5 mM). The first two fractions, obtained at the highest pH values, contained a high proportion of low molecular weight proteins, they spread quickly at the air/water interface and when added to a wheat flour dough they increased the phase angle of the dough. The three following fractions contained a high proportion of high molecular weight proteins, they spread very slowly at the air/water interface and they caused the wheat flour dough to become stiffer (the storage modulus increased) and more elastic (the phase angle δ decreased). The last fractions obtained in amounts enough for investigation were in between the other fractions in the molecular weight distribution and interfacial behaviour, and they hardly affected the rheological properties of the dou

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1989.tb00453.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The compressive force deformation relationships of various foods, that included breads, cheeses and sausages, were described by a two parameter power model.To predict the behavior of double layered arrays of some foods, their model parameters were incorporated into an equation that describes the relationships between the force and the total deformation of the array for a given cross‐sectional area and any initial thickness of each of the two layers. Construction of the force‐deformation relationships of the double layered array was done by numerical solution of this equation for various levels of deformation. The force deformation relationships predicted in this way were found to be in good agreement with experimental relationships. This was irrespective of whether the force deformation curve of the components had a concave upward or downward sh

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1989.tb00454.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Whey protein isolates formed reversible gels following heating at 90°C for 15 min under certain conditions i.e., pH 6.5 to 8.5 with protein concentration of 9.0–10.5%. The melting temperatures of the gels formed at pH 8.0 ranged from 24.5°C to 57.8°C. The maximum enthalpy of formation (ΔHf) was –858 call mole of crosslinks. A maximum storage modulus (G') of 240 dynes/cm2was obtained following holding for 7 h

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1989.tb00455.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Flow parameters of 1:1 mixtures of carrageenan‐guar and CMC‐locust bean gum in the presence of common food ingredients, namely, sugar, salt and proteins, were determined by using a coaxial viscometer. The effect of additives on yield stress, and power law model constants varied depending on the type of ingredient and its concentration, and the nature of the gum. Although, it is interesting to see the flow behavior of gum blends together with the additives in concentrations that are common in food products, it is necessary to study an enormous number of combinations in order to analyze a multicomponent system quantitativ

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1989.tb00456.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Flow characteristics and functional properties of malt extract concentrates were investigated. Flow behavior was studied using a coaxial viscometer over shear rates of 0.6–145.8 s‐1. The shear rate‐shear stress data followed the power law, Casson, Herschel‐Bulkley and Bingham plastic models. Herschel‐Bulkley values for flow behavior index which ranged from 0.73–0.94, and presence of yield stress indicated the Bingham plastic nature of malt extract concentrates. The activation energy of flow for various concentrates was in the range of 14.8–17.7 kcal/gmole. Magnitudes of Reynold numbers (0.0–49.9) for all concentrates were lower than 2100. Temperature, yield stress and plastic viscosity considerably influenced the flow of concentrates in straight pipes. The pressure drop and power requirements for flow of concentrates in pipes at 50°–60°C were lower than those at 30°C, but negligibly different from those at 80°C. Coefficients of correlation between the Bingham plastic values for pressure drop and yield stress (r = 0.86, P<0.01), and plastic viscosity (r = 0.97, P<0.01) were highly significant. Hulled barley and corn concentrates containing high amounts of reducing sugars, showed low viscosities and yield stresses, and required desirably low power for flow in pipes at 50°–60°C. The high protein concentrates of wheat and triticale malts showed high whip volume and good foam stability. Wheat concentrate was superior in fermentability. Hulless barley and finger millet malts produced concentrates with high viscosities which might facilitate their utilization in gums, candie

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1989.tb00457.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

EXTRUSION COOKING.(C. Mercier, P. Linko, and J. M. Harper, eds.), American Association of Cereal Chemists, Inc., St. Paul, MN, 1989. 471 pp., $89.00.WHEAT IS UNIQUE. (Y. Pomeranz, ed.) American Association of Cereal Chemists. 1989. 715 pp. $68.00.

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1989.tb00458.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1989.tb00459.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY