Comparative Analysis of Metabolites of 'Hongro' Apple Greasiness in Response to Temperature

Greasiness in apple skin reduces its quality, and its level varies depending on the variety. In this study, low-temperature (1 +/- 0.5 degrees C) stored 'Hongro' and 'Fuji', which had differences in the occurrence of greasiness, were moved to room temperature (20 degrees C) and untargeted metabolite and fatty acids for skin and flesh along with quality changes due to greasiness occurrence were compared. Ethylene production differed noticeably between the two varieties and increased rapidly in 'Hongro' until 9 d of room-temperature storage. The ethylene production did not differ significantly between the two varieties on day 20 when greasiness occurred. According to the PLS-DA score plot, while 'Hongro' had similar amounts of unsaturated and saturated fatty acids, 'Fuji' had approximately twice as much unsaturated-fatty-acid content. 'Hongro', after 50 d of low-temperature (1 +/- 0.5 degrees C) storage, produced excessive ethylene during room-temperature storage, which was directly related to greasiness development. As a result, the primary wax components of greasy 'Hongro' were nonacosane and nonacosan-10-ol. As the room-temperature storage period elapsed, pentyl linoleate and alpha-farnesene contents increased significantly. Furthermore, these greasiness-triggering characteristics of 'Hongro' may have been genetically influenced by the paternal parent used during breeding.

Automated summary

The quality of apple skin is affected by greasiness, which varies among different apple varieties. This study compared the untargeted metabolites and fatty acids in the skin and flesh of 'Hongro' and 'Fuji' apples, which had different levels of greasiness, during the transition from low temperature to room temperature storage. Ethylene production and fatty acid composition differed between the two varieties, and excessive ethylene production in 'Hongro' during room-temperature storage was related to the development of greasiness. The primary wax components of greasy 'Hongro' were nonacosane and nonacosan-10-ol. Factors triggering greasiness in 'Hongro' may have genetic influences from the paternal parent used during breeding.