Changes in lipid composition of apple surface layer during long-term storage in controlled atmosphere

Apples are the most frequently consumed fruit and about 90 % of apple production is stored. Fatty acids and lipids are important constituents of plant cells. Disturbances in the lipid composition of fruit may lead to various stress processes, resulting in some storage disorders. This work is focused on an analysis of surface lipids of different varieties of apples stored in a normal atmosphere and a modified atmosphere with ultra-low oxygen content, for 4 months and 6 months. The major fatty acids in apple surface layers are palmitic acid, stearic acid, linoleic acid, and oleic acid. During the 6-months storage period, a variety-specific decrease in the total fatty acids content and an increase in saturation degree was observed in all the varieties tested, when compared with the 4-months storage. The greatest differences in saturation degree were observed in the Golden Delicious variety, in which the highest content of unsaturated fatty acids was also found. Microbial contamination of apple surfaces increased gradually over the storage process. Higher fungi levels were found in apples stored in the regular atmosphere than in the modified atmosphere, which can be attributed to changes observed in the total lipid content and saturation degree of the surface fatty acids and also to the sensitivity of microorganisms to the oxygen content in the storage room.