Laboratoire de Biotechnologie d'Olivier, Centre de Biotechnologie de Borj-Cedria, B.P. 901, 2050 Hammam-Lif, Tunisia.
Department of Agriculture, Food and Environment (DAFE), Via del Borghetto 80, 56124 Pisa, Italy.
Molecules. 2019 Feb 2;24(3):545. doi: 10.3390/molecules24030545.
The aim of the present research was to study the effects of olive leaf addition (0 and 3%) on the major antioxidants and the antioxidant activity of Neb Jmel and Oueslati olive oils. Olives and leaves of the two Tunisian varieties were harvested during the 2016/2017 crop season. Both leaves and oils were characterised for their concentrations in phenolics, tocopherols and antioxidant power. Other parameters such as free acidity, peroxide value, chlorophyll and carotenoid concentrations were also taken into consideration. Compared to Oueslati, the Neb Jmel oil showed a lower free acidity (50%) and peroxide value (5.6-fold), and higher chlorophyll (1.6-fold), total phenolics (1.3-fold), flavonoid (3-fold) and oleuropein derivative (1.5-fold) concentrations, in addition to an increased antioxidant activity (1.6-fold). Leaf addition promoted a significant increment in total chlorophyll, α-tocopherol and phenolics in both varieties, above all in Oueslati oil, due to a higher abundance of bioactive constituents in the corresponding leaves. In particular, chlorophyll and carotenoid concentrations reached values twice higher than in Neb Jmel leaves, and flavonoids and oleouperin derivatives were three-fold higher. This prevented the oxidation and the formation of peroxides, reducing the peroxide value of the fortified oil to the half. The results provide evidence on the performance of the Tunisian Neb Jmel and Oueslati varieties, showing that their oils present a chemical profile corresponding to the extra virgin olive oil category and that, after leaf addition, their nutritional value was improved.
本研究旨在研究橄榄叶添加（0 和 3%）对 Neb Jmel 和 Oueslati 橄榄油主要抗氧化剂和抗氧化活性的影响。在 2016/2017 作物季收获了这两个突尼斯品种的橄榄和叶子。对叶子和油的酚类、生育酚和抗氧化能力浓度进行了特征描述。还考虑了其他参数，如游离酸度、过氧化物值、叶绿素和类胡萝卜素浓度。与 Oueslati 相比，Neb Jmel 油的游离酸度（低 50%）和过氧化物值（低 5.6 倍），叶绿素（高 1.6 倍）、总酚类（高 1.3 倍）、类黄酮（高 3 倍）和橄榄苦苷衍生物（高 1.5 倍）浓度更高，此外抗氧化活性也更高（高 1.6 倍）。添加叶子显著增加了两种品种的总叶绿素、α-生育酚和酚类物质，尤其是在 Oueslati 油中，这是由于相应叶子中生物活性成分的丰度更高。特别是，叶绿素和类胡萝卜素浓度达到了 Neb Jmel 叶子的两倍，类黄酮和橄榄苦苷衍生物达到了三倍。这防止了氧化和过氧化物的形成，将强化油的过氧化物值降低到一半。结果证明了突尼斯 Neb Jmel 和 Oueslati 品种的性能，表明它们的油呈现出特级初榨橄榄油类别的化学特征，并且在添加叶子后，它们的营养价值得到了提高。
