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51.
52.
An instrumental technique is described for recording food deformation in texture tests. The time required for the applied force to change between two levels is accurately recorded in digital form. Constant deformation rates are used so that deformation is directly proportional to time. The new readout is demonstrated with springs and selected foods to indicate its performance and show the inaccuracies that occur when using strip-chart recorders to measure deformations. The response of the new system is adequate to test products with a deformability up to 3400 g mm-1 at deformation rates up to 100 cm min-1 with less than 3 % error. 相似文献
53.
The inhibition of tomato pectin methylesterase (PME) by a recently discovered kiwi pectin methylesterase inhibitor (PMEI) is described. PME was consequently purified by CM Sephadex C-50, Concanavalin A-Sepharose 4 B and Mono S chromatography, and PMEI by Q-Sepharose and Sephacryl S-200 chromatography. Inhibition of tomato PME activity under optimal conditions (0.125 m NaCl, pH 7.5) by partially purified kiwi PMEI (MW of 27 kD, pI ≥ 3.67) was independent of the PMEI/PME ratio between 36 and 61% of the maximal uninhibited activity. the non-competitive inhibition observed was optimal in the pH range of 5 to 7. PMEI was inactivated by heating to 120°C, and showed actinidin-like activity towards N-α-benzyloxycarbonyl-L-lysine p -nitrophenyl ester (CBZ-lys-ONp) and azocasein which was partially inhibited by the protease inhibitor leupeptin. 相似文献
54.
ANDREW G. F. STAPLEY JOSÉ A. SOUSA GONÇALVES MICHAEL P. HOLLEWAND LYNN F. GLADDEN PETER J. FRYER 《International Journal of Food Science & Technology》1995,30(5):639-654
Experiments have been carried out using pulsed field gradient NMR to characterize the self-diffusion of water within samples of carrot, both uncooked and cooked by either volumetric electrical or conventional heating. The method detected the presence of structure within uncooked carrot, and the disappearance of the structure on cooking. The NMR data were fitted to two models: (i) an analytical solution for diffusion between impermeable barriers and (ii) a numerical solution to the more physically realistic situation of diffusion between permeable barriers. The barrier spacings obtained with raw carrot data using both methods (i) and (ii) were consistent with cell sizes found in carrots. The effect of cooking on the model fit was either an increase in barrier spacing (method i), or an increase in barrier permeability (method ii). There was a statistically significant difference between samples cooked electrically and conventionally, but this was much less than the difference between cooked and uncooked material. 相似文献
55.
A range of yellow fluorescent 2-pyrazoline acid dyes has been synthesized. Their spectral and dyeing properties (on wool and nylon) depend both on the nature of the substitution pattern of the dye and on the nature of the fibre substrate. Exhaustion and fastness to washing, which are better on nylon than on wool, are improved by substituents attached to the 2-pyrazoline ring. Fastness to light is independent of the fibre and is increased by substituents on the 4- and 5- positions of the 2-pyrazoline ring. The fastness properties of the pyrazoline dyes were compared with those of C.I. Acid Yellow 7. 相似文献
56.
PETER J. WYLLIE 《Journal of the American Ceramic Society》1967,50(1):43-46
Conditions for crystallization of calcite from melts in the presence of a vapor or gaseous phase are reviewed to provide possible guidelines for growth of calcite. Phase equilibrium data for the system CaO-CO2 show that to precipitate calcite from molten CaCO3 the temperature must be above 1230° C and excess CO2 must be present at pressures greater than 39.5 bars. Phase equilibrium data for the system CaO-CO2 -H2 O show that calcite can be precipitated from melts at 650°C in the presence of an aqueous vapor phase at 10 bars or more. Crystallization can be induced either by introducing temperature variations, or by changing the composition of the coexisting aqueous vapor phase under isobaric, isothermal conditions. The system CaO-MgO-CO2 -H2 O is used to show that doped calcite crystals, Cax R1 -x CO3 , could be precipitated, with precisely controlled compositions, from melts in the system CaO-RO-CO2 -H2 O. Apatite phase relations are also presented. 相似文献
57.
Colloidal dispersions of uniform spherical particles of yttrium basic carbonate and rodlike particles of yttrium ammine carbonate were prepared by aging at elevated temperatures yttrium salt solutions in the presence of urea. Different composition and morphology were achieved by altering the aging temperature and time. Coprecipitation in mixed solutions of yttrium(III) and cerium(III) salts under similar experimental conditions yielded composite spherical particles of basic carbonate. The content of the two metals in the solids followed closely the initial composition of the reacting solutions. On calcination all prepared solids converted to their corresponding oxides while retaining their particle morphology. The so-prepared powders were characterized by various techniques. 相似文献
58.
59.
PETER G. HARRIS 《International Journal of Dairy Technology》1982,35(3):104-108
A survey of 8,749 people was conducted in Great Britain to determine the percentage of those who limited or avoided consumption of cow's milk for reasons other than financial. Those who limited or avoided cow's milk consumption were further questioned to determine whether their reasons were perceived by them to relate to allergy/lactose intolerance. Of the sample population 1.47% limited or avoided cow's milk consumption for reasons that might possibly be related to allergy/lactose intolerance . 相似文献
60.
PETER W. VOISEY 《Journal of texture studies》1971,2(2):129-195
Abstract. The use of electronic instruments to record force and deformation in objective texture measurements is reviewed to point out that much equipment is available for that purpose and to indicate some of the problems associated with its use. Electronic transducers are universally applicable to texture measuring systems and can give precise measurements with a high degree of resolution. Several examples of modernized texture instruments are described to demonstrate different methods of approach. Special purpose or ‘universal units’ can be developed. It is concluded that force and deformation can be recorded by electronic techniques in any textural test but that the interpretation of the data is the major problem. 相似文献