Effect of cold storage of olive fruits on the lipoxygenase pathway and volatile composition of virgin olive oil

The lipoxygenase pathway system was studied during storage of 'Picual' olive fruit (Olea europaea) at 20 degrees C and 5 degrees C for four weeks. Key enzymes, lipoxygenase (LOX) and hydroperoxide-lyase (HPL), were assayed during olive fruit storage, and related volatile compounds were analysed in the virgin olive oils produced from these fruit. Clear differences were found in the enzymatic profiles of ambient-stored and cold-stored olive fruit. LOX activity levels remained unaltered in olive fruit stored at ambient temperature but were drastically reduced in fruit stored at 5 degrees C. On the contrary, HPL activity of olive fruit steadily decreased during storage at ambient temperature while no changes in this activity were observed in cold-stored fruit. Changes in the aroma profile of virgin olive oils obtained from olive fruit stored at 20 degrees C and 5 degrees C were related to the patterns observed in LOX and HPL activities. The effect of olive fruit postharvest conditions on the quality of virgin olive oil is discussed.