The relationship between lipid composition and oxidative stability of potato granules

Abstract

Lipid oxidation and changes in the lipid composition of potato granules during storage were studied. In particular, the possible rôle of the free fatty acids (FFA) in oxidation and storage stability was examined. Three potato granule materials which differed in FFA content were stored in darkness, in air at 25°C. The lipid oxidation was followed by gas chromatographic headspace analysis of volatile compounds and sensory evaluation was carried out after periods of 12 and 40 weeks of storage. The FFA were analysed by gas chromatography to determine fatty acid composition during storage. All three of the potato granule materials were markedly oxidized. However, the material containing the least original amount of FFA was the most rancid after only 12 weeks storage, according to both the sensory analysis and the content of hexanal. This shows that there was no connection between the original total amount of FFA and the oxidative stability of the potato granules. In the most highly oxidized material the FFA content decreased towards the end of the storage period, but in the other two materials, for which the rate of oxidation was lower, there was a slight increase of the polyunsaturated FFA ( C18:2 + C18:3). This indicates that both simultaneous lipolysis and oxidation took place during storage. The fatty acid compositions within the lipid classes; neutral lipids, galactolipids, and phospholipids, were not found to change significantly during storage.