Effet Des Extraits Naturels 1. Sur L’inhibition Du Brunissement Enzymatique Des Dattes

Résumé: Enzymatic browningin fruits and vegetables has a negative impact on color, taste, flavor, and nutritional value. Thus, the use of natural compounds with anti-browning capacity would be of indubitable importance for more widespread consumers’ acceptance of these products. In this perspective, the present study was designed to select the natural antioxidant and anti-browning effects of the extracts of by-product from five varieties of local dates of Phoenix dactylifera L.: Deglet Nour, Ghars, Tadala, Tezerzait and Bent Keballah, harvested from the Metlili- Ghardaïa region. Phytochemical analysis of the extracts revealed the presence of significant quantities of several groups of natural compounds, such as tannins, coumarins and reducing compounds. Thus, the quantitative analysis showed the richness of different extracts in total phenols with values varying between 10.65 and 48.98 mg EAG/g DM.Likewise, the flavonoid contents of the different extracts studied are between 1.75 and 15.07 mg RE/g DM.However, a positive relationship (R2= 0.994) was recorded between the flavonoid content and the quantity of total phenols. The in vitro antioxidant capacity of Phoenix dactylifera L. extracts was also evaluated by the DPPH, ABTS and FRAP tests. The antioxidant activity results suggest that our extracts can replace synthetic antioxidants since they have a very high free radical inhibiting potential compared to that observed for the reference antioxidants. On the other hand, the results of anti-browning activity showed that the extracts exhibited a potential inhibition effect on the enzymatic activity of peroxidase from fruits of date palm. This study shows that different studiedparts of date palm, especially the Ghars variety, can be used as effective and natural agents in delaying browning. In addition, HPLC-MS analysis allowed us to identify several phenolic compounds such as coumaric acid, 4-mythoxybenzoic acid, ferulic acid, naringenin, kaempferol, quercetin, valinin, merycetin, folic acid, larutin, gallic acid and chlorogenic acid. According to this study, it seems that the different organs of the Phoenix dactylifera L. constitute a good source of biomolecules, particularly phenolic compounds to be used in food applications or in the pharmaceutical industry for their antioxidant and enzymatic anti-browning effects.

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