摘要:

ABSTRACTThree samples of raw‐milled rice, and 4 differently parboiled rices were used to study and to relate sensory perception to instrumental measurements. Variance analysis showed that some physico‐chemical characteristics indicated great differences among rice samples: thickness of cooked grain, length/width ratio, water uptake, elastic recovery, white core rate and amylose and protein contents. The most discerning sensory attributes were: elasticity, stickiness, pastiness, mealiness, length of grain, firmness, crunchiness, time in mouth, brittle texture and juiciness. The correlation circle of the principal component analysis (PCA) showed high correlation between some sensory characteristics and instrumental measurements. Melting texture, surface moistness, juiciness, were positively correlated with water uptake (r = 0.70, 0.61, 0.71). Granular texture, crunchiness, brittleness and mealiness were significantly affected by white core presence (r = 0.81, 0.74, 0.86, 0.83). Elasticity was dependent upon elastic recovery and firmness measured by the Viscoelastograph, but not linearly. Length of cooked grain was correlated with the length/width ratio of raw grain (r = 0.83). Pastiness, compactness, stickiness were slightly influenced by the thickness of raw grain (r = 0.81, 0.67, 0.72). To a weaker extent, the sensory firmness was associated with the firmness measured by extrusion force using an Ottawa cell (r = 0.58). PCA showed greatdifferences in texture between rices. Two of the parboiled rices were very elastic, another was firm, granular, crunchy and mealy. The remaining two, cooked longer, were moister and more melting. Among the 3 samples of raw‐milled rices, differences in grain length feeling and melting‐granular‐brittle characteristics. were dist

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1995.tb00788.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACTThe rheological behaviour of diluted kiwi concentrates (22.5–63.0 °Brix) over the temperature range 4 to 70C, was studied. The values below 55.7 °Brix fit the power law while above 55.7 °Brix fit the Herschel‐Bulkley equation. Maximum and minimum consistency index values were 62225 and 16 mPa. sn. Concentrates showed a yield stress at 55.7 °Brix, from 5 to 11 Pa, and 63.0 °Brix, from 19 to 53 Pa. Yield stress was correlated with temperature by means of a linear equation. Arrhenius activation energies were in the range of 28.97 to 33.89 kJ/mol. The average value of the flow behaviour indexes varied from 0.85 (sample at 22.5 °Brix) to 0.59 (sample at 63.0 °Brix). Simple equations are proposed to describe the combined effect of temperature and soluble solids content on consistency index and rheological behav

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1995.tb00789.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACTA vertical uniaxial extension apparatus was developed for determining elongational properties of Mozzarella cheese over the course of one month of refrigerated storage. Cheese specimens suspended in hot oil (60C) first underwent melting and then stretching under the influence of a constant force. Samples did not break even after 400% extension. Strain rate and sample temperature both increased during a test. Transient elongational (TE) viscosity of Mozarella cheese decreased with increasing strain rate and sample temperature. Proteolysis of caseins in Moz‐zarella, determined by gel electrophoresis, did not alter its TE viscosity to an extent measurable by our metho

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1995.tb00790.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACTA pin deformation test is assessed for the measurement of the mechanical properties of breakfast cereal flakes where well‐defined procedures like the three point bend test are not easily carried out. These properties are compared with the literature on formed specimens of cereal components, starch polymers and proteins. A classical analysis of a centrally loaded disc on a circular support was used to obtain the Young's modulus, the maximum stress and the maximum strain from the force‐displacement curve. The technique was validated for synthetic polymer discs of known modulus. The Young's modulus for formed discs of starch and gluten as a function of water content agreed reasonably well with independent results using a three point bend test. Formed discs of ground flake showed a similar response to that of gluten. The technique was then applied to individual flakes which were flattened by a hydration‐dehydration procedure and conditioned to different water contents. The stiffness and stress at failure decreased with increasing water content as reported for gluten but their magnitudes were lower, which was attributed to the greater porosity relative to pressed specimens. Some unflattened and low water content flakes were also tested and (although not conforming to the planar geometry of the analysis) showed similarity in stiffness (although not in strength) with their flattened counter

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1995.tb00791.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACTThe potential of mechanical measurements, sensory assessments and electromyography (EMG) to detect the variation in texture properties of beef induced by cooking at temperatures of 45–80C was determined. The mechanical behaviour of meat, from twoSemimembranosusmuscles from one animal, was studied by compression and shear tests in destructive and nondestructive conditions. Electromyographs from the masticatory muscles of 14 trained subjects were recorded during mastication of the meat samples. Texture profiles were completed at the end of each masticatory sequence. Increase in cooking temperature produced an overall increase in shear and compression parameters as well as in meat elasticity. Sensory hardness and total muscle work developed during mastication also increased with cooking temperature. Mechanical measurements, EMG parameters and sensory assessment of texture were highly correlated. EMG, on which the influence of psychological factors is limited, can be used to characterise meat texture objectivel

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1995.tb00792.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACTThe rheological properties of four different infant foods were studied. Flow of all samples showed time dependence, which was qualitatively evaluated and quantitatively described by the Weltman and Hahn models. Rheological data were obtained at a constant shear rate of 57.6 s−1. These foods showed coefficients of thixotropic breakdown between 4.34 Pa. s and 16.69 Pa. s. Values of the Hahn equation parameter were: p from 1.25 to 1.93 Pa and a from 0.019 to 0.031 s−1. The results showed that the Weltman equation was better than the Hahn equation in describing the thixotropic behaviour of these foods. After eliminating time dependency, flow was adequately described by the Herschel‐Bulkley

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1995.tb00793.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACTThe steady‐shear viscosities of cocoa mass and cocoa suspensions were measured over a wide range of temperature and cocoa powder content. The effects of gasification, moisture and lecithin contents were also investigated. The viscosity of cocoa mass followed the Quemada or the Casson model. Both viscosity and yield stress decreased with increasing temperature. Degasification also lowered the viscosity and yield stress. The viscosity of concentrated cocoa suspension increased with increasing powder content and exhibited shear‐thinning behaviour, and followed the Kreiger and Dougherty model. While the relative intrinsic viscosity was nearly constant, the maximum volume fraction increased with increasing shear stress or shear rate. Addition of moisture in suspension increased the viscosity due to partial gelation of starch; while addition of lecithin decreased the viscosity due to the lesser number of flocs in the suspens

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1995.tb00794.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACTSensory viscosity and apparent viscosity of corn starch pastes were studied at 15°, 25°, 37° and 50C, within the concentration range 0.9%–6.2%. The oral and visual sensory viscosity estimations were obtained by the converging limits method, a modified version of magnitude estimation. The exponents (perceptual growth rate) were similar (0.40 oral and 0.41 visual). No significant differences were detected between the two evaluations. Visual stimulation yielded results with a lower deviation, suggesting that this type of judgment is easier for the subject. The consistency of results obtained by the converging limits was determined by comparison of the viscosity of starch pastes with silicone oil by cross‐modality matching. The ratio upper/lower limit of physical range used (13/0.03 for corn starch ∼ 1100/1.80 for silicone oil) is approximately the same for both substances. This is also shown by the fact that the slope of the log‐log function relating them equals 1.11 ± 0.21. No significant effect of temperature was observed on the oral viscosity estimates. The effective range of sensory viscosity for corn starch pastes was between 340

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1995.tb00795.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Grain Quality Evaluation of World Rices. B. O. Juliano and C. P. VillarealFOOD MICROSCOPY, Olga Flint

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1995.tb00796.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

GENERAL PRINCIPLES:Caking and Stickiness of Dairy‐Based Food Powders as Related to Glass Transition. L. E. Chut and T. P. LabuzaGENERAL PRINCIPLES:Phase Behavior and Mechanical Properties of TripalmitinButterfat Mixtures. P. Fairley, J. B. German and J. M. KrochtaGENERAL PRINCIPLES:Heat‐Induced Gels of Rice Globulin: Comparison of Gel Properties with Soybean and Sesame Globulins. N. Yuno‐Ohta, H. Maeda, M. Okada and H. OhtaMETHODOLOGY&INSTRUMENTATION:A New Method for Determination of Normal‐Stress Differences in Highly Viscoelastic Substances Using a Modified Weissenberg Rheometer. H. Eggers and P. SchümmerMETHODOLOGY&INSTRUMENTATION:An Instrument for Precise Measurement of Viscoelastic Properties of Low Viscosity Dilute Macromolecular Solutions at Frequencies from 20 to 500 kHz. T. M. Stokich, D. R. Radtke, C. C. White and J. L. SchragINSTRUMENTAL MEASUREMENTS:Uniaxial Extensional Viscosity During Extrusion Cooking from Entrance Pressure Drop Method. M. Bhattacharya, M. Padmanabhan and K. SeethamrajuSENSORY ASSESSMENT:Oral Assessment of Hardness Between Elastic and Plastic Products. M.‐A. Peyron and L. MiocheFACTORS AFFECTING TEXTURE:Microwave Blanching Effects on Chemical, Sensory and Color Characteristics of Frozen Green Beans. M. S. Brewer, B. P. Klein, B. K. Rastogi and A. K. PerryFACTORS AFFECTING TEXTURE:Gel Strength Increased in Low‐Grade Heat‐set Surimi with Blended Phosphates. R. G. Nielsen and G. M. PigottFACTORS AFFECTING TEXTURE:Kappa‐Carrageenan, Sodium Chloride and Temperature Affect Yield and Texture of Structured Beef Rolls. P. J. Shand, J. N. Sofos and G. R. SchmidtFACTORS AFFECTING TEXTURE:Chuck Longissimus and Infraspinatus Muscle Characteristics as Affected by Rigor State, Blade Tenderization and Calcium Chloride Injection. J. Benito‐Delgado, N. G. Marriott, J. R. Claus, H. Wa

ISSN:0022-4901    

DOI:10.1111/j.1745-4603.1995.tb00797.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY