Chemistry Reference
In-Depth Information
LIPIDS
OILS, FATS, AND WAXES;
SOAP
10
Lipids
, from the Greek word
lipos
, for animal fat or vegetable oil, is the
generic chemical term for
oils
,
fats
, and
waxes
(see Table 77). In the body of
living organisms the lipids serve as highly concentrated, long-term storage
substances of the excess energy acquired or created by the body. If and
when the organism requires it, the energy stored in the lipids can be released
back to the body, yielding more than twice the amount of energy supplied
by equal weights of carbohydrates or proteins. In animals, fat under the
skin also provides a thermal insulating layer that prevents heat from
escaping from their bodies and protects them from extreme external
temperatures.
10.1.
OILS, FATS, AND WAXES
All the lipids are viscous when liquid and greasy (lubricious) to the touch.
Some, as for example tallow and suet, are solid and hard at ambient tem-
perature, others, such as lard and butter, are solid and soft, while still others
are liquid, as are olive and linseed oils. Lipids that are solid at room tem-
perature are generally of animal origin and are traditionally known as
fats
;
those that are liquid at ambient temperature are derived mostly from plants
and are known as
oils
. The properties of a wide range of lipids, natural fats,
oils, and waxes have been known to humans for a long time and have been
put to multifarious uses; some are consumed as foodstuffs, others are burned
as fuel for lighting, or used as lubricants (for turning wheels and moving
heavy objects), to protect - insulate and waterproof - or to decorate the
surface of a variety of solids (Evershed et al. 2001; Serpico and White 2000a).
