Valve homogenizers

E. Tomherg Punctional Characterization of Protein Stabilized Emulsions Emulsifying Behavior of Proteins in a Valve Homogenizer. J. Sci. Pood Agric. 29, 867 (1978). 

Figure 7. Fat surface area of the protein-stabilized emulsions as a function of power consumption after emulsification with a valve homogenizer using 10 passes through the recirculating system ( ll,)...

The word homogenization is somewhat inconclusive and is typically defined as used in context. Two processes are considered here the first is a fine clearance valve homogenizer, and the second is a rotor-stator-type mechanical homo-genizer. Homogenization is similar to sonication and produces submicron droplets by a combination of mechanical shearing and cavitation. 

Figure 6. Technical schematics of the three most often used homogenization devices (a) highspeed blender, (b) high-pressure valve homogenizer, and (c) colloid mill.

Experiments have shown that the smallest droplet size that can be achieved using a high-pressure valve homogenizer increases as the disperse phase volume fraction increases (52). There are a number of possible reasons for this, (1) increasing the viscosity of an emulsion may suppress the formation of eddies responsible for breaking up droplets, (2) if the emulsifier concentration is kept constant, there may be insufficient emulsifier molecules present to completely cover the droplets, and (3) the rate of droplet coalescence is increased. 

Microfluidizer The microfluidizer operates much the same as the valve homogenizers, but has a proprietary interaction chamber rather than an expansion valve. While valve homogenizers often have difficulties with particle slurries due to wear and clogging of the homogenizing valves, microfluidizers are much more robust and are often used in pharmaceutical processing. Interaction chambers for these apphcations must be made of specialized materials and can be expensive. Slurry particle sizes similar in size to those in media mill operations can be achieved with the microfluidizer. 

Corredig, M. and Wicker, L. (2001). Changes in molecular weight distribution of three commercial pectins after valve homogenization. Food Hydrocolloids 15,17-23. 

Valve homogenizers ultrasonic mixers None Usually continuous 0.1 < d32 < 10pm Sparse data work with vendors feed is predispersed... 

Whiteley, A.J., and Muir, D.D. (1996). Heat stability of homogenised concentrated milk. 1. Comparison of microfluidiser with a valve homogenizer. Milchwissenschaft 51, 320-323. 

Homogenizers valve homogenizers, ultrasonic mixers continuous 0.1 < 5 32< 10 p sparse data work with vendors... 

High-speed dispersing units 128 Valve homogenizers 130 Ultrasonic homogenizers 130 Extruders 132 Equipment selection 136... 

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