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Back extrusion, compressive

Penetrometers are easy to use giving good results and correlating well with the sensory assessment of gels etc. Nevertheless these instruments yield a purely empirical method working on the principal of linear compression, penetration or back extrusion. [Pg.408]

The major cation present In fruits and vegetables Is K. Its concentration can be affected by environmental factors, principally the amount of available E In the soils or root media f 16, Different applications of E resulted In more than a two-fold difference In snap bean pod E (JD, Table III. Higher pod E levels were associated with softer beans when measured after a standard canning procedure. Firmness values In this table and In Tables IV-V1 and In Figures 1 and 2 were obtained as kg force resistance to compression In a back extrusion coll (Jl). [Pg.192]

Illustrated In figure 1, Is modified from a design described by Bourne and Moyer(1968). The Instron cross-head Is moved at 100 mm/mln. A sample of material, contained In the cup, Is compressed as the plunger comes down. At length, the material extrudes back through the annulus between plunger and cup wall. A typical force-distance curve Is shown. The rise reflects the compression, and the plateau of the back extrusion. We use the plateau force as a measure of firmness. Ten replicate measurements are performed. Repeatability Is better than 4. ... [Pg.201]

Finally, compression-extrusion testing involves an extrusion cell commonly used for weakly structured, homogeneous food products. This apparatus consists of a piston that is forced into a cylinder open at one end and containing the product (Figure H2.2.5). Beyond the point of rupture of the food, the compressed material is forced to flow back through the annular space between the piston and the cylinder (Bourne, 1976 Edwards, 1999). The gap between the piston and the cylinder is called the annulus (Bourne, 1982). Variation in the annulus width results in variation in the force required for extrusion (Bourne, 1982). [Pg.1183]

Ethylene, isobutane, comonomer and catalyst are continuously fed to the loop reactor where polymerization occurs at temperatures lower than 100°C and pressures of approximately 40 kg/cm2 and residence times of approximately one hour. Ethylene conversion exceeds 97% per pass. Reactor effluent is flashed to separate the solid resin from the gaseous stream (3). Polyethylene powder is purged (4) with nitrogen to remove traces of hydrocarbons and pneumatically conveyed to the extrusion area for stabilization and pelletizing. The gaseous stream is compressed, purified and recycled back to the reactor. [Pg.89]

Air entrapment is a rather common problem in extrusion. It is caused by air being dragged in with particulate material from the feed hopper. Under normal conditions, the compression of the solid particulate material in the feed section will force the air out of the solid bed. However, under some circumstances the air cannot escape back to the feed hopper and travels with the polymer until it exits from the die. As the air pockets exit from the extruder, the sudden exposure to a much lower ambient pressure may cause the compressed air bubbles to burst in an explosive manner. However, even without the bursting of the air bubbles, the extrudate is generally rendered unacceptable because of the air inclusions. [Pg.834]


See other pages where Back extrusion, compressive is mentioned: [Pg.199]    [Pg.1173]    [Pg.33]    [Pg.312]    [Pg.282]    [Pg.584]    [Pg.324]    [Pg.248]    [Pg.349]    [Pg.361]    [Pg.267]    [Pg.268]    [Pg.307]    [Pg.309]    [Pg.808]    [Pg.809]    [Pg.1010]    [Pg.309]    [Pg.154]    [Pg.308]    [Pg.787]    [Pg.49]    [Pg.1070]    [Pg.265]    [Pg.390]    [Pg.282]    [Pg.573]    [Pg.305]   


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