Mechanical oil expression

Mechanical pressing of liquid out of liquid-containing solids is referred to as expression . The conventional theories about oil expression from oilseeds were based on the assumption that oilseed cell walls were non-porous hence, they had to be raptured by mechanical and thermal treatment before substantial oil expression could be achieved (Mattil et al 1964). A later theory has suggested that the pores (plasmodesmata) of certain biological cell walls 

A growing number of mini crushing mills, which employ extruding-expelling (E-E) technology, have been bnilt as farmer-owned cooperatives or as on-farm operations to process locally prodnced soybeans or other oilseeds. E-E uses a dry extruder in which heat is generated internally by friction and dissipation of mechanical energy prior to screw 

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Mrema GC, McNult PB. 1984. Microstructure of Rapeseed and Cashew as Related to Mechanical Oil Expression. Ir. J. Fd Sci Technol. 8 59-66. 

Mrema GC, McNulty PB. 1985. Mathematical Model of Mechanical Oil Expression from Oilseeds. J. Agric. Eng. Res. 31 361-370. 

Essential oils are natural substances mainly obtained from vegetable raw materials either by distillation with water or steam or by a mechanical process (expression) from the epicarp of citrus fruits. They are concentrated fragrance and avor materials of complex composition, in general volatile alcohols, aldehydes, ethers, esters, hydrocarbons, ketones, and phenols of the group of mono- and sesquiterpenes or phenylpropanes as well as nonvolatile lactones and waxes. 

Most properties of the P/M part are closely related to the final density of the part expressed in g/cm. Normally, density of mechanical and stmctural parts is reported on a dry unimpregnated basis density of bearings is reported on a fiiUy oil impregnated basis. Density may be calculated by any of several means. The commonly used method is given (44). 

In the older method, still used in some CIS and East European tar refineries, the naphthalene oil is cooled to ambient temperatures in pans, the residual oil is separated from the crystals, and the cmde drained naphthalene is macerated and centrifuged. The so-called whizzed naphthalene crystallizes at ca 72—76°C. This product is subjected to 35 MPa (350 atm) at 60—70°C for several minutes in a mechanical press. The lower melting layers of the crystals ate expressed as Hquid, giving a product crystallizing at 78—78.5°C (95.5—96.5% pure). This grade, satisfactory for oxidation to phthaHc anhydride, is referred to as hot-pressed or phthaHc-grade naphthalene. 

Volatile Inhibitors. Of the volatile components that influence plant growth and development, ethylene has received the most attention. Literature concerned with the variety of effects produced by ethylene, factors which influence its production, and the mechanisms through which responses are expressed has been reviewed by Evenari (57). Other gaseous excretions with inhibitory effects considered by Evenari include hydrogen cyanide, ammonia, essential oils, and mustard oils (probably allyl isothiocyanate and /3-phenethyI isothiocyanate). 

Live oil with dissolved methane does not follow the above correlations as methane relaxes by a spin-rotation mechanism, even when dissolved in liquid hydrocarbons [13]. The Ti relaxation time as a function of rj/T is illustrated in Figure 3.6.2 for different gas/oil ratios expressed in units of m3 m-3 as a parameter. The solid line is the fit for zero gas/oil ratio and is given by Eq. (1). 

Expression is the use of a crushing, mechanically applied pressure to squeeze oils from plant material. It was originally done by hand but is now mechanized, with use of centrifugal separators. Expression is used almost exclusively for citrus fruits with oil glands in the outer rind of the fruit. 

Expression A mechanical method using compression and pressure for removing essential oils from the skins of citrus fruits, e.g. lemon, orange, bergamot. 

Canola Oil occurs as a light yellow oil. It is typically obtained by a combination of mechanical expression followed by n-hexane extraction, from the seed of the plant Brassica juncea, Brassica napus, or Brassica rapa (Fam. Cruciferae). The plant varieties are those producing oil-bearing seeds with a low erucic acid (C22 i) content. It is a mixture of triglycerides composed of both saturated and unsaturated fatty acids. It is refined, bleached, and deodorized to substantially remove free fatty acids phospholipids color odor and flavor components and miscellaneous, other non-oil materials. It can be hydrogenated to reduce the level of unsaturated fatty acids for functional purposes in foods. It is a liquid at 0° and above. 

Palm Kernel Oil (Unhydrogenated) is a fat obtained from the kernel of the fruit of the oil palm Elaeis guineensis Jacq. (Fam. Arecaceae) by mechanical expression or solvent extraction. It is refined, bleached, and deodorized to substantially remove free fatty acids, phospholipids, color, odor and flavor components, and miscellaneous other non-oil materials. Like coconut oil, it has a more abrupt melting range than other fats and oils. 

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