Fatma Abbès

Phenolic profile, antibacterial and cytotoxic properties of second grade date extract from Tunisian cultivars (Phoenix dactylifera L.)

The present study aimed to investigate the phenolic profile of second grade date extracts and evaluate their antimicrobial and cytotoxic activities with regard to some pathogenic microorganisms. Phenolic content was analyzed by HPLC. Antimicrobial activity was evaluated by the agar disk diffusion method, and in vitro cytotoxic activity was examined by cell proliferation assay. The results revealed that second grade dates presented three benzoic acids, five cinnamic acids and two flavonoids, with the predominance of ρ-coumaric acid (1998.80μg/100g). The antimicrobial activities showed that the date extracts were active against Gram (+) and Gram (-) bacteria, showing marked activity against Escherichia coli with an inhibition zone of 25mm. Cytotoxicity assays showed that the date extracts were able to inhibit the proliferation of HeLa cell lines. The results confirmed that the date extracts were rich in biologically active compounds that are highly valued in the functional food and nutraceutical industries.

In Vitro Antioxidant Activities of Three Selected Dates from Tunisia (Phoenix dactylifera L.)

Second-grade dates (Phoenix dactylifera L.), with hard texture, from three selected Tunisian cultivars (Allig, Deglet Nour, and Bejo) were analysed from their antioxidant activities using DPPH radical scavenging activity, FRAP assay, H2O2 scavenging activity, and metal chelating activity. Date extracts showed strong and concentration-dependant activity in all tested methods. The results showed that the best antioxidant activity was obtained in Allig, followed by Bejo and Deglet Nour. Total phenolics, total flavonoids, carotenoids, and tannins were determined spectrophotometrically in three date extracts. Results indicated that date contained significantly different amounts of these compounds. In fact, Allig presented the highest antioxidant compounds, followed by Bejo and Deglet Nour. Correlation analyses indicated a positive linear relationship between antioxidant activities and total phenolic and flavonoid content of date. This study demonstrates the potential antioxidant activity with Tunisian date, where we can use these natural extracts as food additives in replacement of synthetic compounds.

Effect of concentration temperature on some bioactive compounds and antioxidant proprieties of date syrup

The effect of the concentration temperature on the antioxidant activity, carotenoid and phenolic compounds of date syrup was investigated. Date juice was concentrated at 100 ℃ and at “60 ℃ in vacuum”. After concentration, total phenolic, tannin, non-tannin, flavonoid and carotenoid content were determined spectrophotometrically and high-performance liquid chromatography was used for determination of 5-Hydroxymethyl-2-furfuraldehyde content. The antioxidant activity of date syrup was evaluated by various antioxidant methods including total antioxidant, 2,2-diphenyl-1-picrylhydrazyl free radical scavenging test, ferric reducing antioxidant power and β-carotene bleaching. All date syrups showed strong antioxidant activity accompanied by high total phenolic contents. Results showed that concentration at 100 ℃ significantly enhanced the antioxidant activities and total phenolic contents of date syrups compared to vacuum concentration at 60 ℃. A good correlation between the antioxidant activity and total phenolic content and flavonoid was observed.

The addition effect of Tunisian date seed fibers on the quality of chocolate spreads

Novel chocolate spreads were enriched by soluble and insoluble dietary fibers from Tunisian Deglet Nour date seeds at 1, 2, 3, 4, and 5% levels in the conventional chocolate spread. Defatted Deglet Nour date seeds, date seed soluble fiber concentrate (DSSFC) and date seed insoluble fiber concentrate (DSIFC) were characterized by high levels of dietary fibers (80-90%). Chocolate spread enriched with 5% of DSSFC presented the highest oil binding capacity (304.62%) compared to the control (102%). Whatever the DSIFC and DSSFC incorporation levels, no significant difference was recorded between the firmness, chewiness, and adhesiveness of prepared chocolate spreads compared to the control (p < .05). Sensory evaluation revealed that all prepared chocolate spreads enriched by DSIFC and DSSFC were accepted by panelists. These results indicated the value of date seeds as new source of dietary fibers to develop chocolate spread and could also improve health benefits and functional properties. PARACTICAL APPLICATION Tunisia is considered to be one of the dates-producing countries. The mean annual yield of date fruits is about 200,000 tons. From this, around 20,000 tons of date seeds could be collected. This by-product of date processing industries could be regarded as an excellent source of dietary fiber with interesting technological functionality and many beneficial effects on human health. Then, date seeds could present a value addition by extraction and use of date seed fiber concentrate in chocolate spread formulation.