Nutritional properties, aromatic compounds and in vitro antioxidant activity of ten date palm fruit (Phoenix dactylifera L.) varieties grown in Tunisia

Abstract Phoenix dactylifera L. has traditionally been used as a medicine in many cultures. The aim of this study was to evaluate the nutritional properties, aromatic compounds, total phenolic content and the antioxidant activity of ten ripe date fruit varieties grown in Tunisia. Sugar profiles were analyzed by high performance liquid chromatography, while fatty acid compounds were detected by gas chromatography and aromatic compounds were analyzed by GC-Electron Impact Mass Spectroscopy. Total phenolic contents were measured using colorimetric methods, whereas antioxidant capacities were evaluated in vitro using DPPH and ABTS radicals. It has been found that total sugars are the predominant component in all date varieties, followed by moisture, along with moderate amounts of proteins, ash, and fats. Multivariate tests based on the volatile compounds profile showed significant differences among varieties. Between the sixty-two volatile compounds detected, alcohols, aldehydes and unsaturated hydrocarbons constituted the main chemical classes. The date varieties exhibited strong antioxidant potential that correlated with phenolic content. In conclusion date varieties can play a major role in human nutrition and health because of their wide range of valuable nutritional components and natural antioxidants that could potentially be considered as a functional food ingredient.

Influence of Tunisian Ficus carica fruit variability in phenolic profiles and in vitro radical scavenging potential

Ficus carica L., Moraceae, is one of the first plants that were cultivated by humans, being the fruit an important crop worldwide for dry and fresh consumption. In this work, phenolics and antioxidant potential of dried fruits of seventeen Tunisian F. carica varieties, from green, red and black phenotypes, were assessed for the first time. HPLC-DAD analysis was performed. All samples presented a similar qualitative profile. The phenolics content ranged between 29.18 and 55.56 mg/kg (in black and red phenotypes, respectively) and quercetin-3-O-rutinoside was always the major compound. The antioxidant potential against DPPH•, superoxide and nitric oxide radicals of three varieties representing each phenotype was checked. All samples exhibited activity against the first two radicals in a concentration-dependent way, "Bayoudi" variety being the most effective one (IC25 values of 10.32 and 2.89 µg/ mL, respectively). Nevertheless, only "Hammouri" variety presented some capacity to scavenge nitric oxide radical. Our results reveal nice perspectives for these typical fruits, as they present an interesting phenolic composition and good antiradical activity and may encourage their consumption for health protection.