We are all familiar with the unpleasant experience of eating peanuts or crisps that are too old, or with the smell and taste of rancid butter. This is due to oxidation of the fats and oils in these foods and it affects all types of food that contain them: meat, fish, nuts etc.
Because of their chemical structure, unsaturated fats and oils are subject to oxidative breakdown, so-called oxidative rancidity. This reaction is a free radical chain reaction that involves abstraction of hydrogen from the fatty acid chain followed by a series of reaction with oxygen, rearrangements, and chain cleavage to produce nasty smelling and tasting compounds.
This investigation looks at some of the factors that can affect the rate at which this oxidation occurs – using β-carotene as a proxy marker to visualise the process.
Oxidative Rancidity – Pupil Guide
Oxidative Rancidity – Teacher/Technician Guide
Oxidative Rancidity – Risk Assessment
The short video about emulsions which you can watch below, can be downloaded here if your internet connection does not allow online viewing – right click and select ‘save link as . . .’ or ‘save target as . . .’).