Summary Notes on Oxidation/Reduction and Antioxidants (Includes exam style question and answer)

- OXIDATION/REDUCTION AND
ANTIOXIDANTS -


OXIDATION/REDUCTION:



Oxidation being loss of electrons, GAIN of OXYGEN or LOSS of HYDROGEN.
Reduction is the gain of electrons, LOSS of OXYGEN or GAIN of HYDROGEN.

This is how the oxygen to hydrogen ratio is affected.

Loss of hydrogen would increase the O:H ratio in a molecule and gain of hydrogen would
reduce the O:H ratio.




ANTIOXIDANTS:



Antioxidants are molecules that reduce the rate of oxidation reaction involving the transfer
of electrons to an oxidizing agent. Antioxidants will prevent oxidation reaction taking
place, antioxidants are reducing agents. By undergoing oxidation, the antioxidant provides
electrons to prevent the oxidation of fats/oils in food. Antioxidants are often added to
foodstuff to minimise oxidative damage.

Simpler definition:
Antioxidants are reducing agents that slow down the rate of oxidation.


Oxidative damage would cause the breakdown of proteins in meat, oils and fats and the
foods would become rancid. This is a term used to explain the ‘off’ smell that out of date
foods have. The rate of oxidation of food stuff can be slowed down by reducing the
temperature by refrigeration. Packaging under a vacuum or under an inert gas such as
nitrogen can also reduce the oxidation rate by reducing the concentration of oxygen (air).