Mechanical expelling

In Asia, sesame oil is obtained by pressing the roasted oilseeds and consumed as a naturally flavored oil without refining. In the western world, sesame oil is extracted by a multiple-step mechanical expeller and either the virgin oil or the... 

A combination of mechanical and solvent extraction is often applied to oilseeds with high oil content, e.g., sunflower, safflower, com germ, and canola. The most efficient method of extracting the oil is mechanically expelling about 60% of the oil and then using solvent extraction of the remaining oil. 

The triethylamine generates a carbanion on a to the ketone, which evolves by an EicB mechanism, expelling a carboxylate. 

The vegetable oils from seeds and beans are typicaUy obtained by both physical extraction (mechanical expeller pressing) and chemical extraction, usually with hexane as a solvent (a petroleum-derived fraction without any aromatic hydrocarbons) and by a combination of both processes. If the seed oil content is lower than 25%, the oil is obtained by direct extraction. From seeds with higher... 

UnKke animal fats, which are usually used without further treatment, vegetable oils obtained from seeds by mechanical expelling and solvent extraction have unpleasant organoleptic properties. Therefore, these oils are refined in order to be more acceptable to consumers. The refining process includes ... 

Figure 2. Samples of com germ, ground com germ, and com germ meal obtained after SC-CO2 extraction at the University of Burgos. Com germ bagasse obtained after mechanical expelling is also included for comparison.

The bran is usually channeled to animal feeds, although recently it has started to be further milled and sized for direct food applications. The germ is usually channeled to oil-crushing industries where the oil is mechanically expelled and/or chani-cally extracted with hexane. The pericarp, germ cake, standard meal, and broken kernels are usually combined and hammer milled to produce hominy feed (Chapter 18). 

Rice bran, consisting of the pericarp, seed coat, germ, and aleurone tissues, accounts for 7%-10% of the rough rice weight. The bran is rich in protein, fat, minerals, and B-vitamins (Juliano and Bechtel 1985) (Chapter 18). In Asia, rice bran is used as a raw material for production of rice oil. Both mechanical expellers and hexane extraction systems are used. Solvent extraction usually yields 16%-18% oil and defatted rice bran with less than 1% residual oil, whereas mechanical pressing leaves around 10% oil, yielding partially defatted rice bran prone to oxidation. Recently, whole stabilized and defatted rice bran has been viewed as a source of important antioxidants and nutraceuticals with health-promoting effects. In Europe and America, rice bran is mainly used as poultry, cattle, and swine feed (Chapter 18). 

The obvious intermediate, 239A, will now react with some aluminium species to give an intermediate like 239B, which can react further if the lone pair on nitrogen halps to expel the oxygen atom. Try now to complete the mechanism. 

Compressed gas systems were originally developed simply to provide a means of expelling a product from its container when the valve was depressed. SemisoHd products such as a cream, ointment, or caulking compound are dispensed as such. A Hquid concentrate and a compressed gas propellant (Fig. 3) produce a spray when a mechanical breakup actuator is used. Nitrogen, insoluble in most materials, is generally used as the propellant. 

According to the second mechanism the polymer and antimony trioxide form a catalytic complex. The halogen flame retardant then reacts with the complex and expels antimony tribromide. 

The addition-elimination mechanism uses one of the vacant n orbitals for bonding interaction with the nucleophile. This permits addition of the nucleophile to the aromatic ring without displacement of any of the existing substituents. If attack occurs at a position occupied by a potential leaving group, net substitution can occur by a second step in which the leaving group is expelled. 

Mechanical Force. Liquid can be readily expelled from a spongelike particulate mass of solid by using various pressing techniques. With this method, mechanical energy is used to force the liquid containing the particulate matter through a porous bed. The particulate matter is held in the pores in the bed. When the pressure drop reaches a certain level, replacement or backwashing takes place. This process may be either intermittent or continuous. 

Interestingly enough, both protons at C-11 are exchanged quite readily in 12-keto steroids. In these compounds C-11 is the only possible enolization site where the axial (/3) proton is probably expelled first. During ketonization, the deuteron attack is more likely to occur from the less hindered a-side. By this sequence the proton which was originally at the lla-equato-rial position becomes axial and readily available for expulsion in the next enolization step. Thus, isomerization of the C-11 hydrogens may be an important reason for the facile exchange at this position. (For a more detailed discussion of the mechanism of enolization and ketonization reactions, see ref 114.)... 

The differenee in reaction rates of the amino alcohols to isobutyraldehyde and the secondary amine in strong acidic solutions is determined by the reactivity as well as the concentration of the intermediate zwitterions [Fig. 2, Eq. (10)]. Since several of the equilibrium constants of the foregoing reactions are unknown, an estimate of the relative concentrations of these dipolar species is difficult. As far as the reactivity is concerned, the rate of decomposition is expected to be higher, according as the basicity of the secondary amines is lower, since the necessary driving force to expel the amine will increase with increasing basicity of the secondary amine. The kinetics and mechanism of the hydrolysis of enamines demonstrate that not only resonance in the starting material is an important factor [e.g., if... 

The reaction of a tertiary alcohol with HX takes place by an Sf l mechanism when acid protonates the hydroxyl oxygen atom, water is expelled to generate... 

Naturally occurring compounds called cyanogenic glycosides, such as lotau-stralin, release hydrogen cyanide, HCN, when treated with aqueous acid. The reaction occurs by hydrolysis of the acetal linkage to form a cyanohydrin, which then expels HCN and gives a carbonyl compound-fa) Show the mechanism of the acetal hydrolysis and the structure of the cyanohydrin that results. 

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