Determining the oxidation stability of fats and oils using the Rancimat method.
Foodstuffs that contain fat – like butter, nuts, cookies, and potato chips – turn rancid over time. This is caused by chemical changes in the fat; in particular, its oxidation. Because of this, determining the oxidation stability of fats and oils in foods has proven to be a useful tool in the quality control of foodstuffs. And the Rancimat method is designed to perform this exact task.
Double bonds: Twice as much isn’t always twice as good
Fats are glycerin triesters with three fatty acid residues (Figure 1). The extent to which fatty acid residues react with substances in their environment depends on their chemical structure; where fats in foodstuffs are concerned, this mainly involves atmospheric oxygen. The double bonds in monounsaturated or polyunsaturated fatty acids are particularly reactive; as such, fats and oils containing unsaturated fatty acid residues demonstrate lower oxidation stability than those containing only saturated fatty acid residues.