Monitoring seasonal variation in apple fruit volatile emissions in situ using solid-phase microextraction

Emissions of volatiles from apple fruits (Malus domestica Borkh.) were monitored in situ over the course of a growing season (from early June to mid September) for two apple varieties, Golden Delicious and Maigold. Results indicate a characteristic time-course of volatile emissions as the sampling date was a statistically significant factor for nine of the 13 compounds considered. The amounts of volatiles collected were greatest early and late in the season. The temporal effect on emissions was generally much larger than the effect of variety, which was significant for only four of the 13 compounds considered. The possible sources of variation which are not explained by the statistical models are discussed, and it is considered that they are most likely related to differences in the emissions from individual fruits.