Vegetable oils fractionation

The choice of the term oil or fat usually is based on tradition and the physical state of the material. Generally, oils are liquid at ambient temperatures, and fats are semisolid mixtures of crystals in oil. Fats often are of animal origin (beef tallow, pork lard, and butter fat) or hardened (hydrogenated, interester-ified, or thermally fractionated) vegetable oils, whereas oils are extracted from plant seeds or tissues or fish. In English-speaking countries outside the United States, oils liquid at room temperature sometimes are called soft oils, and those hard or pasty are called hard oils. Nutritionists generally use fats for solids or liquids. 

Coal-derived liquids, heavy petroleum fractions, vegetable oils and polymers are mixtures that have very large numbers of components. It is practically impossible to identify each component by ordinary chemical analysis. One can no longer use mole fractions of individual components. Traditionally, the pseudo-component approach, or the key component approach, has been used to handle such complex mixtures. 

Example Fractionation of Fatty Acids. A mixture of waste acids from a vegetable oil refinery are to be separated into five fractions as shown in Table 1. 

FoodApphca.tlons, Carbon dioxide, a nontoxic material, can be used to extract thermally labde food components at near-ambient temperatures. The food product is thus not contaminated with residual solvent, as is potentially the case when usiag coaveatioaal Hquid solveats such as methylene chloride or hexane. In the food iadustry, CO2 is not recorded as a foreign substance or additive. Supercritical solvents not only can remove oils, caffeiae, or cholesterol from food substrates, but can also be used to fractionate mixtures such as glycerides and vegetable oils iato aumerous compoaeats. 

The first engines invented by Rudolf Diesel ran on groundnut oil, but because of the advent of relatively cheap oil this type of biodiesel never became commercially viable. Since about 1930 the diesel engine has been refined and fine tuned to run on the diesel fraction of crude oil, which consists mainly of saturated hydrocarbons. For this reason the modem diesel engine cannot run satisfactorily on a pure vegetable oil feedstock because of problems of high viscosity, deposit formation in the injection system and poor cold-start properties. Today, however, environmental... 

ESPIN J c, soLER-RivAS c and WICKERS H J (2000) Characterization of total free radical scavenger capacity of vegetable oils and oil fractions using 2,2-diphenyl-1 -picryUiydrazyl radical, JAgric Food Chem, 48, 648-56. 

PTLC was used to enrich the polar fraction of deep-fried potato chips and vegetable oils used in industrial frying operahons. After PTLC, capillary GC, GC-MS, and NMR were used to quantify sterols and sterol oxides in fried-potato products, as well as the composition of sterols in the oil used for frying [72]. 

Surfactants belong to a group of products where a low price is crucial, and therefore they are usually synthesized from coarsely defined mineral oil fractions or vegetable oils both of which represent (sometimes complex) mixtures (Fig. 11.25). Cationic and anionic surfactants are readily detected by ESI, but it also serves well for the detection of non-ionic surfactants which tend to form [MH-alkali]" or [M-H] ions, respectively. [124-128]... 

Vegetable oils have the potential to substitute a fraction of petroleum distillates and petroleum-based petrochemicals in the near future. Vegetable oil fuels are not petroleum-competitive fuels because they are more expensive than petroleum fuels. However, with recent increases in petroleum prices and uncertainties concerning petroleum availability, there is renewed interest in using vegetable oils, called biodiesel, in diesel engines. 

Other systems that have been investigated are the separation of biocides from edible oils and fractionation of different components in vegetable oils. An example of the latter is given next. For an extensive literature survey of work done in the area of SFE, see references [31-34]. 

A cylindrical extractor, 1-m long, is filled with crushed-vegetable-oil seeds. The oil is to be extracted with pumping supercritical carbon dioxide at a density of 500 kg/m3 through the packed bed. The estimated solubility of the oil in the dense gas at this density is 3.425 kg/m3. The superficial velocity of the carbon dioxide in the bed will be 1 mra/s. This fluid velocity is sufficiently small for the fluid to become saturated with oil. We are required to estimate the minimum time of operation for complete extraction of the oil from the bed. The initial oil fraction is 12% (wt/wt) based on wet seeds, the void fraction of the bed is 40%, and the density of the particles is 900 kg/m3. 

MYRISTIC ACID. [CAS 544-63-8]. Also called tetradecanoic acid, formula CHjlCHiJnCOOH, At room temperature, it is an oily, white crystalline solid. Soluble in alcohol and ether insoluble in water. Specific gravity 0.8739 (80°C) mp 54.4°C bp 326.2°C. Combustible. The acid is derived by the fractional distillation of coconut oil. Myristic ucid is used in soaps cosmetics in the synthesis of esters for flavorings and perfumes and as a component of food-grade additives, Myristic acid is a constituent of several vegetable oils. See also Vegetable Oils (Edible). 

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