2. Need of Hydrogenation
• Number of double bonds in oils and fats
affects physical property such as melting
point, crystallinity
• Generally, double bonds reduce the oil’s
melting point
3. Definition
• Hydrogenation is a chemical process
where hydrogen add to double bonds of
unsaturated fatty acids produces
saturated fats
• It convert alkenes to alkanes and carried
out by H2 gas through the heat , in the
presence of a metal catalyst (such as
nickel or platinum)
4. For example complete hydrogenation
of linoleic acid generates stearic acid
which used in cosmetics
and in pharmaceuticals
5.
6.
7. Hydrogenation of Unsaturated Oils
• Unsaturated oils are usually only partially
hydrogenated, so that the product is not
completely saturated, giving a soft semisolid
fat such as margarine
• This forms a new type of fatty acid called
trans-fatty acid, (“man-made” fat).
• Trans-fatty acids have many of the same
properties asSATURATED fats.
8. Cis and Trans Unsaturated Fatty Acids
• Natural unsaturated fatty acids have cis
double bonds.
• When unsaturated vegetable oils are
hydrogenated to form more saturated oils (as
in margarine), some of the cis fatty acids are
isomerized to trans fatty acids.
• Trans fatty acids are much more linear than cis
fatty acids
9. Cis and Trans Unsaturated Fatty Acids
• Their melting points are higher.
• Studies have shown that trans fats may act
similarly to saturated fats and could
contribute to heart disease and some cancers.
• Due to new requirements for including
amounts of trans fats on food labels, many
companies are developing hydrogenation
methods that do not produce trans fats
11. Main purposes of hydrogenation oils
to solid or semi-solid fats
• They are a cheap substitute of saturated fats
from animal origins, such as lard or butter
• Hydrogenated oils are more stable than
unsaturated oils. The process of
hydrogenation transforms fatty acids that
are prone to oxidative rancidity,
especially in high temperatures during
cooking;
12. • Vegetable oils used in hydrogenation are
usually more uniform in length with medium
to long chains and after saturation are more
stable. point, are easily manipulated by
changing the degree of saturation.
• For instance, the final product may be
hardened or softened by adjusting how much
hydrogen is added during the process;
