Shortening is trans fatty acid. Shortening is a common cooking oil that is mostly used in cakes, puffed foods, and other foods. Trans fatty acids are fatty acids that have hydrogen ions on both sides of the carbon chain, and its generally called trans fatty acids.

Trans fatty acid is a general term for unsaturated fatty acids that contain a trans non-***-conjugated double bond structure. Fatty acids are divided into saturated fatty acids (satu-rated fatty acid, SFA) and unsaturated fatty acids (unsaturat-ed fatty acid, UFA), of which unsaturated fatty acids are fatty acids that contain at least one carbon-carbon double bond on the fatty acid chain.

If the two hydrogen atoms bonded to the two carbon atoms on the double bond are on the same side of the carbon chain, and the spatial conformation is curved, then it is called a cis-unsaturated fatty acid, which is also the form of the vast majority of unsaturated fatty acids in nature. On the other hand, if the two hydrogen atoms bound to the two carbon atoms on the double bond are on both sides of the carbon chain, and the space conformation is linear, then it is called trans-unsaturated fatty acids.

Structural Properties

Trans fatty acids are non-***-conjugated unsaturated fatty acids that contain one or more trans double bonds in the molecule. The two hydrogen atoms connected to the carbon atom forming the trans double bond are located on both sides of the carbon chain, whereas the double bond in natural fatty acids is mostly cis, with the hydrogen atoms located on the same side of the carbon chain. The bond angle of the trans double bond is smaller than that of the cis isomer.

The serrated structure of the space for the linear rigid structure, these structural features make it with cis fatty acids with different properties, with a higher melting point and better thermodynamic stability, the nature of more similar to saturated fatty acids. The melting point of trans fatty acids is affected by the number of double bonds, bond shape and position.

Reference: Baidu Encyclopedia-Trans Fatty Acids