Abstract: In order to explore the mechanism of the effect of low temperature storage on the metabolism of aroma-related esters in ‘Nanguo’ pears, the changes in the composition of aroma-related esters, and the activities and protein expression of lipoxygenase (LOX) and alcohol acyltransferase (AAT), the key enzymes for the metabolism of aroma-related esters, in Nanguo pears during cold storage and subsequent shelf life at ambient temperature were investigated. Results showed that compared with storage for 90 days, the number of aroma-related esters, the content of the major aroma components and total ester content after 180 days of storage and after subsequent ripening at ambient temperature until the optimal consumption date significantly decreased. There was no significant difference in the activities and protein expression of LOX and AAT during cold storage. However, during the shelf life at room temperature after cold storage, the activities and protein expression of LOX and AAT reached the maximum levels three days earlier in the 180-days stored fruits than the 90-day stored ones. Moreover, the former showed a significant reduction in AAT activity and the protein expression levels of LOX and AAT. These results indicated that long-term refrigeration could inhibit the activities and protein expression of the key enzymes for the biosynthesis of aroma-related esters to a certain extent, thus affecting the generation of aroma-related esters and reducing the aroma quality of Nanguo pears.

Key words: ‘Nanguo’ pears, cold storage, volatile esters, protein expression