Ripening attributes of new passion fruit line featuring seasonal non-climacteric behavior

The passion fruit hybrid cultivar 'Passion Dream' (PD) produces two cycles of fruiting per year, in the summer and winter. Self-hybridization of PD created various lines, including 'Ripens during Summer' (RS), which lacks the ability to abscise during winter, suggesting a seasonal nonclimacteric behavior. The two lines were characterized by several quality traits: PD produced high ethylene levels in both seasons; RS produced significantly less ethylene during summer and almost none during winter. The ratio of total soluble solids to titratable acidity (TSS/TA), and aroma volatiles production, as determined by solid-phase microextraction/gas chromatograph-mass spectrometer (SPME/GC-MS) techniques, and taste indices were highest in PD summer fruits and lowest in RS winter fruits. Peel color in PD was affected by environmental and storage temperatures, whereas RS fruits always showed a strong purple color. The present findings suggest that ethylene production levels in passion fruit greatly influence various ripening processes, including acid degradation, increased TSS/TA ratio, accumulation of aroma volatiles, and tastiness.