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
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.
Unrefined oils are darker and have a more pronounced flavor than refined oils. However,
this stronger flavor is not to be confused with rancidity. Refining has an effect on the
nature of the oil, as well as on their vitamin and mineral content, color (lighter),
flavor, and cooking qualities. After refining, an antioxidant (vitamin E or an additive)
is added to the oil if its vitamin E content is not adequate to protect the oil against
oxidation. The equipment used for the above processes are extremely complicated to kosher
sterilize if it was used for a non-kosher production. That is one of the reasons many
kosher certifiers will not even entertain as an option to use a facility for a kosher
production one that also does non-kosher (An "av"=animal vegetable plant).