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. 2023 Aug 1;28(15):5807.
doi: 10.3390/molecules28155807.

A Sustainable Approach for the Valorization of Underutilized Date Fruits

Amel Hamdi  1   2 , Isabel Viera-Alcaide  1 , Susana Costa  3 , Teresa Lino-Neto  3 , Rafael Guillén-Bejarano  1 , Rocío Rodríguez-Arcos  1 , Ana Jiménez-Araujo  1
Affiliations

A Sustainable Approach for the Valorization of Underutilized Date Fruits

Amel Hamdi et al. Molecules. .

Abstract

Secondary varieties of date fruits are often discarded because they do not have commercial value. However, their phytochemicals are very similar to those of the primary ones and therefore, they can be valorized as a source of compounds of interest, mainly phenols and dietary fiber. Their chemical composition changes with ripening, so their characterization throughout this process is of great significance. Date fruit samples were harvested at Khalal, Rutab, and Tamer stages, and a mixture of fruits from ornamental date trees was also analyzed. Aqueous and ethanolic extracts were studied for their phenolic composition. In aqueous extracts, phenols decreased with ripening, while in the ethanolic ones having higher phenolic content. Chelidonic acid, a γ-pyrone, was the major compound found in all extracts, but in the ethanolic ones, flavonoids were also present in similar amounts. After purification by adsorption chromatography, all extracts were assayed for their antimicrobial activity. Those from the Tamer stage showed the highest activity, especially against Gram-positive bacteria. The fibrous residues after aqueous and ethanolic extractions were also characterized. Their chemical composition suggested that they can be considered as a good source of prebiotic arabinoxylans and antioxidant fiber, whose antiradical activity correlated with their phenolic content. Date fruits from secondary varieties are promising as a worthwhile starting point for obtaining new value-added products.

Keywords: agricultural by-products; antimicrobial activity; antioxidant capacity; date fruit; dietary fiber; phenolic composition; prebiotics; secondary variety; valorization.

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Conflict of interest statement

The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.

Figures

Figure 1
Figure 1
Water and total sugar contents (on fresh weight basis) of the different samples analyzed. The results are the average value of at least three replicates, and the error bars represent standard deviation. Different letters on bars mean significant differences at p < 0.05.
Figure 2
Figure 2
Bioactive compound composition of ethanolic (a) and aqueous (b) extracts of the four samples analyzed, expressed as mg/100 g dry weight. The same letter means that there are no significant differences (p < 0.05) among different maturity stages for a particular phenolic compound.
Figure 3
Figure 3
Composition of non-cellulosic sugars of fibrous fractions from ethanolic (a) and aqueous (b) extracts of the four samples analyzed, expressed in percentages. The same letter means that there are no significant differences (p < 0.05) between different maturity stages for a particular sugar and extraction.
Figure 4
Figure 4
Samples analyzed. (A–C) are fruits from the same non-commercial P. dactylifera variety at different maturation stages ((A) Khalal; (B) Rutab; (C) Tamer) and (D) is a mixture of fruits from different ornamental varieties from P. dactylifera species harvested at different stages of ripeness.
See this image and copyright information in PMC

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