Physico-chemical changes and volatile constituents observed in 10 apricot cultivars (Prunus armeniaca L.) during post-harvest ripening

Abstract

Physico-chemical changes included a significant decrease in firmness during post-harvest ripening, whereas the levels of total soluble solids were found to be very similar. Ethylene as a parameter of ripening contributed to the resolution of cultivars in the over-ripe phase. On the other hand, fruit softening was not a useful parameter for distinguishing cultivars. 59 of volatiles were determined by the static headspace SPME gas chromatography with mass spectrometry and included 18 alcohols, 12 aldehydes, 10 esters, 11 terpenes, 5 lactones and 3 miscellaneous. Actually, the production of alcohols at ripe stage had almost been completed, since at the over-ripe stage they increased only slightly. Terpene levels were highest for the medium-late cultivars (Orangered, Velkopavlovická, Pinco, Silvercot and Leskora); they were predominantly limonene, α-terpineol and β-Ionone. The decrease in the concentration of terpenes in over-ripe fruit was statistically significant. There are six compounds (2-methylbutan-1-ol, 2-methylbutanal, n-hexylbutanoate, 3-methyl- 3-methylbutyric acid, γ-caprolactone and γ-octalactone) which taken together can be used to distinguish the two different stages of maturity, ripe and over-ripe. The most abundant of these are γ-caprolactone and γ-octalactone, followed by 2-methylbutan-1-ol. If the volatiles from the cultivars used in this investigation are compared using cv. Bergeron as a standard, then only 10 are required to separate each variety at the over-ripe phase. Principal component analysis clearly separated the cvs Velkopavlovická and Bergeron from all the others, which probably reflects major differences in the production of volatiles and ethylene.