Olive Leaf Addition Increases Olive Oil Nutraceutical Properties

Abstract

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.

Total Tocopherols, Carotenoids, and Fatty Acids Content Variation of Pistacia atlantica from Different Organs’ Crude Oils and Their Antioxidant Activity during Development Stages

“…Significant differences were observed in leaves and galls oils among oil yield, tocopherols and carotenoids means in all the development stages at P < 0.05. Our results of leaves oils tocopherols and carotenoids content registered high values comparing with olive leaves oil of the two varieties reported by Tarchoune et al, [33] where the carotenoids content did not exceed '44.33 μg/g DW' and '82.37 μg/g DW' for tocopherols. Furthermore, no research has dealt with the chemical composition of tocopherols and carotenoids of P. atlantica Desf.…”

Gene Expression Pattern in Olive Tree Organs (Olea europaea L.)

“…The expression profiles in the six analyzed plant organs are shown in Figure 1. The fact that more than half the expressed genes (32,030) were expressed in all the tested plant organs suggests many putative housekeeping genes. However, many of these genes displayed very low expression levels in one organ or more, which means that their expression was organ-or tissue-dependent.…”

Chemical Analysis of Minor Bioactive Components and Cannabidiolic Acid in Commercial Hemp Seed Oil

“…Furthermore, it has been reported that the hemp seed oil contains a huge amount of chlorophylls that are able to interfere with oxidative stability and rancidity [14]. These natural pigments act as powerful prooxidants, increasing the susceptibility to light-induced oxidation or photo-oxidation of the edible oils when exposed to light and promote change from the intensive dark green color to yellow [15,16]. Several refining processes are needed during the hemp seed oil production to reduce the chlorophyll content and other minor components such as metals and phospholipids that could affect the oil quality.…”