Saturday, October 22, 2016
Temperature also has a marked effect on the rate of autoxidation. Generally, the autoxidation rate increases as the temperature is increased.
At the ordinary temperatures, the effect if increasing on the rate of autoxidation is slightly greater than for chemical reactions because increasing temperatures accelerates both the chain propagation reactions and peroxide decompositions. Low temperature storage helps to minimize temperature-induced oxidation.
The solubility of oxygen in an oil decreases with an increase in temperature therefore the effect of oxygen concentration on the rate of oxidation becomes less evident.
For example, by cooling the milk for some times before its use (at least 2 hours at 5 C), a part of the copper on the fat globules moves to the plasma; this may restricted the autoxidation. Moreover, the cooling causes a migration of protein to the plasma, and this precisely the protein that liberates H2S during heat treatment.
Temperature affecting autoxidation of fats