Abstract:

Refrigeration delays ripening and reduces decay of pear fruit, but this benefit is offset by a loss of aroma when
the fruit is then ripened at room temperature. Intermittent warming (IW) has been used to alleviate chilling injury (CI) of
fruit; however, its effect on aroma remains unknown. In this study, Nanguo pears were subjected to IW and changes in
aroma-related esters, the activities and gene expression of lipoxygenase (LOX), alcohol dehydrogenase (ADH) and alcohol
acyltransferase (AAT) were investigated. Significantly higher ester contents were found in IW-treated fruit on day 0 of the
shelf life at room temperature and in the optimal taste period. The activity of LOX was promoted by IW treatment during
the early period of the shelf life at room temperature and the activity of ADH was promoted on day 6 of the shelf life, while
the activity of AAT was accelerated during cold storage and the shelf life at room temperature. The transcription levels
of PuLOX1, PuADH3 and PuAAT1 genes were significantly promoted by IW treatment. IW treatment may regulate the
activities and gene expression of LOX, ADH and AAT to stimulate the generation of aroma-related esters. Treatment with
IW effectively prevented the loss of aroma-related esters from refrigerated Nanguo pears.

Key words: Nanguo pears, intermittent warming, refrigeration, volatile esters, gene expression