Patterns of Volatile Diversity Yield Insights Into the Genetics and Biochemistry of the Date Palm Fruit Volatilome

Volatile organic compounds are key components of the fruit metabolome that contribute to traits such as aroma and taste. Here we report on the diversity of 90 flavor-related fruit traits in date palms (Phoenix dactylifera L.) including 80 volatile organic compounds, which collectively represent the fruit volatilome, as well as 6 organic acids, and 4 sugars in tree-ripened fruits. We characterize these traits in 148 date palms representing 135 varieties using headspace solid-phase microextraction gas chromatography. We discovered new volatile compounds unknown in date palm including 2-methoxy-4-vinylphenol, an attractant of the red palm weevil (Rhynchophorus ferrugineus Olivier), a key pest that threatens the date palm crop. Associations between volatile composition and sugar and moisture content suggest that differences among fruits in these traits may be characterized by system-wide differences in fruit metabolism. Correlations between volatiles indicate medium chain and long chain fatty acid ester volatiles are regulated independently, possibly reflecting differences in the biochemistry of fatty acid precursors. Finally, we took advantage of date palm clones in our analysis to estimate broad-sense heritabilities of volatiles and demonstrate that at least some of volatile diversity has a genetic basis.

Antioxidant and Nutritional Properties of Date Fruit from Elche Grove as Affected by Maturation and Phenotypic Variability of Date Palm

Some parameters related to nutritive and functional properties were evaluated in date fruit from seven date palms from the Elche grove along the maturation process, in order to obtain information about differences due to phenotypic variability. Results showed that sugar and organic acid concentration were different depending on date palm, the highest levels being reached at 100% Rutab stage, with glucose and fructose as the predominant sugars and malic acid as the major organic acid. Hydrophilic total antioxidant activity (HTAA) was high and correlated to phenolic content, with maxima levels being found at early, medium or late Khalal stages, depending on date palm. In addition, significant differences were found in both, phenolic concentration and HTAA among date palm and maturation stages, while lipophilic total antioxidant activity (LTAA) was very low, without changes along maturation and not correlated to HTAA. Then, date fruit from Elche grove could serve as a good source of natural antioxidant and it would be advisable to consume them at medium or late Khalal stages, in order to achieve the maxima nutritional (high concentration of sugars and organic acids), organoleptic (appropriated firmness levels, yellow or red color and low astringency) and functional properties with benefits to human health.