Oils, composition and properties

Seed oil and protein are highly heritable traits in flax and can be selected for in early generations (see Oil Composition and Properties). Canadian flax breeders aim for 50% oil and 25% protein content on a dry matter basis. 

Petroleum chemistry is concerned with the origin, composition, and properties of naturally occurring petroleum deposits, whether in liquid (crude oil or petroleum), gaseous (natural gas), or solid (tars and asphalts) form. All of them are essentially mixtures of hydrocarbons. Whereas natural gas contains a few lighter hydrocarbons, both crude oil and tar deposits may consist of a large number of different hydrocarbons that cannot be easily identified for molecular structure or analyzed for composition. 

Gray, G.R., Darley, H.C.H., Rogers, W.F. "Compositions and Properties of Oil Well Drilling Fluids" 4th Ed, Gulf Publishing Houston, TX 1980. 

In general, surface activity behaviour in food colloids is dominated by the proteins and the low-molecular-weight surfactants. The competition between proteins and surfactants determines the composition and properties of adsorbed layers at oil-water and air-water interfaces. In the case of mixtures of proteins with non-surface-active polysaccharides, the resulting surface-activity is usually attributed to the adsorption of protein-polysaccharide complexes. By understanding relationships between the protein-protein, protein-surfactant and protein-polysaccharide interactions and the properties of the resulting adsorbed layers, we can aim to... 

In addition, the crude oils available today to the refinery are quite different in composition and properties to those available some 30 years ago (Swain, 1998 Speight, 1999). The current crude oils are somewhat heavier insofar as they have higher proportions of nonvolatile (asphaltic) constituents. In fact, by the standards of yesteryear, many of the crude oils currently in use would have been classified as heavy feedstocks, bearing in mind that they may not approach the definitions used today for heavy crude oils. Changes in feedstock character, such as this tendency to heavier materials, require adjustments to refinery operations to handle these heavier crude oils to reduce the amount of coke formed during processing and to balance the overall product slate. 

Chemical changes result in the formation of new substances when the composition of the original substance is changed for example, when a metal reacts with the oxygen of the air it forms a new substance called an oxide (as when iron goes rusty). Essential oils can also react with oxygen, which alters their chemical composition and properties. Other chemical reactions can be... 

The general name chamomile is very misleading as there are three main species producing essential oils for aromatherapy. Each produces an essential oil with a different composition and properties. The species are Roman... 

The main essential oil-producing species of Eucalyptus include Eucalyptus globulus, also called blue gum eucalyptus Eucalyptus dives, known as broadleaved peppermint eucalyptus Eucalyptus citriodora, known as lemon-scented eucalyptus Eucalyptus radiata, known as narrow-leaved peppermint gum Eucalyptus smithii, known as gully gum and Eucalyptus polybractea, known as blue mallee. Within each species there are many subspecies and chemo-types. This illustrates a very complex situation, producing essential oils with varying compositions and properties. 

The essential oils have also been shown to have bacteriostatic activity. They are generally considered to be safe when used correctly externally but there is a possibility of sensitization by Eucalyptus globulus in some individuals. Taken internally, eucalyptus oils are toxic. When choosing a eucalyptus essential oil the varying compositions and properties must be carefully considered in the context of the client s condition. 

When an essential oil is used for massage, it is diluted in a carrier or base oil. Carriers are vegetable oils such as sweet almond, grapeseed, wheatgerm, jojoba, etc. They have different compositions and properties and these are briefly described in Chapter 7. The resultant mixture of essential oil and carrier is called a blend. The amounts used or dosages are rather subjective and will vary according to a number of factors. 

Fearon, A.M., Mayne, C.S., Beattie, J.A.M., Bruce, D.W. 2004. Effect of level of oil inclusion in the diet of dairy cows at pasture on animal performance and milk composition and properties.. / Sci. Food Agr. 84, 497-504. 

The fatty acid or alcohol groups present in an ester can be exchanged in a number of ways by reaction with an excess of other fatty acids (acidolysis), alcohols (alcoholysis), or other esters (interesterification). Generally, the starting point will be a triacylglycerol, and these reactions provide routes by which the composition and properties of oils and fats can be modified. 

There is considerable interest in the chemical composition and properties of citrus oils and essences as well as the role they play in food and nonfood industries. Citrus peel oils and essences possess a pleasant aroma, with oxygenated compounds being the major constituents that account for their characteristic odor. Terpenes, the most abundant components in cold-pressed citms peel oil, are removed in concentrated oil production, usually by use of adsorbant and supercritical carbon dioxide, to increase the concentration of oxygenated compounds and to enhance the qualification of the oil. Meanwhile, citms seed oils are composed largely of triacylglycerols and are rich in oleic and linoleic acids. 

Garcia Del Pozo JA, Alvarez Martinez MO. Olive oil attainment, composition and properties. Farm (ElFarmaceutico) 2000 241 94, 96, 98-100, 102, 104-105. 

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