Studies on the lipid oxidation and oleosomes behavior in raw pecan kernels during storage.

ABSTRACT

The oxidative stability of pecan kernels and its relationship with the in-vitro behavior of oleosomes during storage were analyzed. The oxidation index of oil extracted from pecans stored for 20 days increased significantly. At the same time oleosomes in pecans were damaged, indicating a relationship between oleosomes and the oxidative stability of pecans. The rupture of oleosomes increases contact between oil and oxygen leading to an acceleration of oil oxidation. Further analysis of oleosomes showed that their oil content decreased during storage while their particle size increased significantly. It is possible that hydrolysis of endogenous proteins, especially oleosins, was responsible for the rupture of oleosomes, as seen by Tricine-SDS-PAGE. As a result, the content of free fatty acids and oxidized triacylglycerols in oleosomes increased, whereas the polyunsaturated fatty acids content decreased significantly. An in-vitro model confirmed that rupture of oleosomes led to oil leakage and thus accelerated endogenous oil oxidation.