Food suspensions

The discussion above that led to Eqs. (4.2.6 and 4.2.7) assumes that the no-slip condition at the wall of the pipe holds. There is no such assumption in the theory for the spatially resolved measurements. We have recently used a different technique for spatially resolved measurements, ultrasonic pulsed Doppler velocimetry, to determine both the viscosity and wall slip velocity in a food suspension [2]. From a rheological standpoint, the theoretical underpinnings of the ultrasonic technique are the same as for the MRI technique. Flence, there is no reason in principle why MRI can not be used for similar measurements. 

Extrusion cooked foods Suspension in 0.02% CaClj, enzymatic hydrolysis, filtration Spherisorb ODS2 column, (25 x 0.49 cm 5 pm) Linear gradient HjO/MeOH DAD (190-600 nm) [85]... 

Tablet may be taken without regard to food. Suspension and capsule should be taken on an empty stomach... 

Many foods are oil-in-water or water-in-oil emulsions (o/w), with dispersed particle size range of 0.01-10 p.m (Rahalkar, 1992). Many of the equations discussed for food suspensions are also applicable to emulsions. In a dilute emulsion, the particles are far apart and the interparticle interactions are relatively weak. Skim milk is an example of a dilute emulsion with the concentration of fat droplets (dispersed phase) <1%. 

Yoo, B., Rao, M. A., and Steffe, J. F. 1995. Yield stress of food suspensions with the vane method at controlled shear rate and shear stress. J. Texture Stud. 26 1-10. 

The solid particles in PF dispersions are not of simple shapes (e.g., spheres, rods) and they are deformable, and have multimodal size distributions (Tanglertpaibul and Rao, 1987a). Also, the particles are hydrated and are in physical and chemical equilibrium with the continuous medium so that they differ significantly from artificial fibers such as of glass or of synthetic polymers. The continuous phases of PF dispersions also have features that are different than those of non-food suspensions. The continuous medium of a typical food dispersion, usually called serum, is an aqueous... 

Because no general theories exist even for concentrated non-food suspensions of well defined spherical particles (Jeffrey and Acrivos, 1976 Metzner, 1985), approaches to studying the influence of the viscosity of the continuous medium (serum) and the pulp content of PF dispersions, just as for non-food suspensions, have been empirical. In PF dispersions, the two media can be separated by centrifugation and their characteristics studied separately (Mizrahi and Berk, 1970). One model that was proposed for relating the apparent viscosity of food suspensions is (Rao, 1987) ... 

Rao, M. A. 1987. Predicting the flow properties of food suspensions of plant origin. Mathematical models help clarify the relationship between composition and theological behavior. Food Technol. 41(3) 85-88. 

Dzuy and Boger (2) employed a mixer viscometer for the measurement of yield stress of a concentrated non-food suspension and called it the "vane method . Yield stress of apple sauce samples was determined by means of the vane method by Qiu and Rao (22) using two vanes. The maximum recorded torque (Tm) value, and the diameter (Dv) and the height (H) of the vane were used to calculate the yield stress (Ov) according to the equation ... 

Because no general theories exist even for concentrated non-food suspensions of well defined... 

The model predicts the viscosity of the serum when the pulp content is zero. The coefficient A indicates the contribution of a unit amount of pulp content and the coefficient B is the slope of a plot of log pulp vs. log specific viscosity of the dispersion and it reflects the relative intensity of pulp content in different food suspensions or the effect of different processes and/or cultivars that could influence the pulp content. The magnitudes of B for the tomato concentrates, COJ, and apple sauce varied over the limited range of 1.26 - 1.49, suggesting that there was not much difference in the influence of pulp content. For tomato concentrates and apple sauce, the contribution of the dispersed solids was much more than that of the continuous medium (43.). ... 

Wall effects in capillary flow of suspensions such as apple sauce occur as a result of velocity gradient near the wall that in turn causes the suspended particles to move away from the wall region. The net result is slip of the fluid at the wall (23., 24.) The correct shear rate can be calculated from flow rates corrected for slip. The procedure, due to Mooney (42.), requires the use of several capillaries of different different length to diameter ratios has been applied to food suspensions by Higgs (38) and Kokini and Plutchok (22.) to show that slip effects are significant. These results also suggest caution in using... 

Food suspensions are made by any of the suspension preparation techniques described elsewhere in this book (see, for example. Section 7.1.3). Related to food suspensions are a variety of microencapsulated ingredients used in foods, which are usually in the form of a suspension at some stage in their production. The... 

There are. however, many gums that have been (and still are) used in the preparation of suspensions some examples are (3,72) agar, alginates, guar gum. and xanthan gum. the latter being the most frequently found in i iarmaceutical and food suspensions. Figure 14 is a schematic representation of this polysaccha-... 

Food suspensions may be aqueous dispersions, for instance tomato ketchup, mustard, etc., or oil-continuous dispersions, such as melted chocolate. The interparticle interactions are strongly influenced by the properties of the continuous phase, which will make oil-continuous systems very different from water-continuous systems. In addition, the solution, structural and chemical properties of the dispersed phase strongly influence the properties of these systems. 

Benzoic acid and its salts may be determined by titration with sodium hydroxide after extraction of the benzoic acid from an aqueous food suspension into chloroform, and evaporation of the chloroform and any acetic acid present (AOAC method 963.19). Vanillin interferes with this determination and a more selective method involves the determination of benzoic acid in an ether extract by UV absorption at 272 nm, as described in AOAC method 960.38. An alternative method of isolating benzoic acid from food involves the use of steam distillation and TLC separation. These sample preparation techniques are used in AOAC method 967.15 prior to the determination of benzoic acid by UV absorption. 

The volatile aroma compounds, together with some water, are removed by vacuum distillation from an aqueous food suspension. The highly volatile compounds are condensed in an efficiently cooled trap. The organic compounds contained in the distillate are separated from the water by extraction or by adsorption to a hydrophobic matrix and reversed phase chromatography and then prefractionated. 

Degussa P25 Ti02 FTO Spin coating Pt/FTO Pt black/ SUS mesh 60 mM NH3 solution pig urine food suspension One-compartment cell Biomass and biowaste 500 WXe lamp (lOOmWcm-2) Kaneko et a. (2009b)... 

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