Oil is an unctuous fatty substance that is insoluble in water, and the vegetable & fruit derived oils are usually liquid at room temperature. The Palm oil, Coconut oil & animal fats are solid at room temperature. The first form of oil was melted animal / poultry fat. The first pressed oils were olive oil. The most commercially important oils in the world today are soybean oil, palm oil and rapeseed (canola) oil. Different countries use primarily different oils, for example the Pacific Rim use mainly palm, coconut & soybean oils. In Europe the most important oils are Canola oil, sunflower oil, soybean oil & peanut oil. Their import & shipping of oils will also be dependent on what they have available to them.

Vegetable oils primary sources are soybeans, peanuts, sunflower, rapeseed, pumpkin, corn, olives, palm, nuts, hazelnuts, grape seeds, almonds and cotton. Oil is also extracted from animals, fish & mammals e.g. whale, seal, halibut & cod. The kosher consumer would be concerned with the grapeseed oil, animal oil, fish & mammal oils even as unprocessed raw oils.

Oils are extracted mechanically either cold pressed or hot pressing (with or without a solvent). Using hydraulic presses at a maximum temperature of 172F performs COLD PRESSING. Cold extraction requires that the material being pressed have a minimum fat content of 30%. Cold-pressed oils are not subject to further treatment (only filtering). It should be noted that since there is no legal definition of "cold-pressed oil", oils marketed as such may not actually be cold-pressed.

"Extra-virgin oil" is obtained from the first pressing of oil with an acid content of less than 1%. "Virgin oil" is also a first extraction with a maximum acid content of 3%. "Fine" oil is a blend of extra-virgin & virgin oil. The designation "100% pure" refers to the fact that the oil comes from a single source, as opposed to a blend of different oils; it is often obtained from the second pressing of the product. The process of cold pressing leaves over in the pulp close to one third of the oil, while heat pressing will limit the loss to about 5%, & the addition of a solvent lowers it even further to 1%. The most common solvent used is a solution of hexane (hexane, acetone, and water). HEAT PRESSING is a process by which the pulp is passed through heated screw presses at a temperature of between 208F & 280F. The resulting oil is called by different names mainly, crude oil, raw oil, or unrefined oil. Crude oil pressed using the heat method must be subjected to several treatments before it can be used.

The resulting pressed oil is called by different names mainly, crude oil, raw oil, or unrefined oil. Crude oil pressed using the heat method must be subjected to several treatments before it can be used. BLEACHING: eliminates the pigments present in crude oil. DEGUMMING: involves removing the free fatty acids and small quantities of proteins, and other substances that contribute to the instability of the oil and to the production of froth and smoke during deep-frying. DEODORIZATION: produces oil with a neutral flavor that does not transfer any specific flavor to foods; this process eliminates traces of substances that causes oil to go rancid, thus prolonging its shelf life once it is bottled.

FRACTIONATION: is performed to prevent the oils from crystallizing at low temperatures (in the refrigerator, for example). The crystals are removed by filtration after the oil has been cooled.

HYDROGENATION: involves treating the oil with hydrogen to prevent oxidation and to convert liquid oils into semisolid or solid shortenings. Therefore the higher the degree of hydrogenation, the more solids the fat. REFINING OR NEUTRALIZATION: consists of adding an alkaline substance (often caustic soda) to the already degummed oil in order to transform its free fatty acids into soap, which is then extracted from the product by centrifugation. ANTIOXIDATION TREATMENT: involves adding synthetic antioxidants that prevent oxidation of the oil as long as the container is sealed. Although a natural antioxidant, vitamin E, is present in oil and vegetable fats (it is more abundant in cold-pressed than hot-pressed oils), the oil is protected against oxidation only until these natural antioxidants are used up. That is the reason why cold-pressed oils must be stored with greater care than refined oils.