Focus on Olea europaea L. pruning by‐products: extraction techniques, biological activity, and phytochemical profile

Abstract

The Olea europaea L. tree has played a central role in Mediterranean culture since ancient times. Several studies have highlighted the health‐promoting properties both of its primary products (olives) and its by‐products (leaves, pomace, husk, stone, mill wastes, and wood). In this study, pruning residues from 25‐year‐old olive trees located in a Mediterranean region (Basilicata, Italy) were analyzed. The antioxidant activity of hydro‐alcoholic extracts from wood samples were analyzed through three complementary in vitro assays. The molecular composition of the extracts was thoroughly evaluated using a gas chromatography apparatus coupled with a mass spectrometer (GC–MS). Our study demonstrated that all but three extracts had remarkable antioxidant activity, which was likely due to the meaningful presence of phenolic compounds, mostly derived from lignin. Moreover, the results showed that bark extracts obtained with ultrasound‐assisted extraction (UAE) had the highest antioxidant activity. In this extract, several known compounds with demonstrated antioxidant activity were found, including hexylresorcinol, 1‐methyl‐N‐vanillyl‐2‐phenethamine, and allopurinol. This research suggests that woody olive by‐products are a potential natural resource of antioxidants. These compounds could be useful for functional foods and in industry, and could help to solve the problem of pruning residues, increasing their potential economic value. © 2021 The Authors. Biofuels, Bioproducts and Biorefining published by Society of Industrial Chemistry and John Wiley & Sons Ltd.

Variability and chemical composition of the extractive content of woody residues from three European orchard species: apricot (Prunus Armeniaca L.), olive (Olea Europea L.), and orange trees (Citrus Sinensis L.)

“…In the olive tree wood samples, the higher extraction yield was measured in the trunk and the bark as reported also in the previous study. 33 Klari c et al, 2016 38 explained the bark's high extractive content since the bark owing the main biological functions to protect the tree's essential living systems (e.g., extreme temperatures, attacks from fungi, insects, and animals). Moreover, also based on our results, we observe that the pruning residues showed a greater range of variability and extractive yield compared to the trunk, evidences found also in other studies.…”

Wood Waste from Fruit Trees: Biomolecules and Their Applications in Agri-Food Industry

“…The production of olive wood discarded during olive pruning could vary from 3.5 to 10.5 kg/tree each year, which results in between 1.31 and 3.02 tons of discarded wood/ha [ 12 , 20 ]. In Spain, this is around 7 million tons of wood per year that is not leveraged.…”

“…The authors reported the following concentrations of phenolic compounds: verbascoside (1338–1681 mg/kg dw), apigenin-7-glucoside (10–16 mg/kg dw), and luteolin-7-glucoside (167–202 mg/kg dw). Faraone et al [ 20 ] studied the presence of phenolic compounds in olive tree wood using GC-MS. The results exhibited a total phenolic compound content of 156.040 mg/kg dw and antioxidant activity of 188.840 mg Trolox equivalent (TE)/kg dw.…”

Optimization and Comparison of High-Pressure-Assisted Extraction of Phenolic Compounds from Olive Pomace

“…1 Mediterranean countries such as Spain, Italy, Greece, Portugal, Greece, and Turkey provide 97% of the total olive oil production in the world and represent a major industry in the region. 2,3 Olive pomace, a solid byproduct of olive oil production, is nearly 40% of the total weight of olives being processed in the mill. 4 It includes a high concentration of phenolic compounds, and so olive pomace has a high polluting organic load and a phytotoxic effect, and this results in a significant environmental hazard.…”

“…Over the last few years, olive oil consumption has increased worldwide, and nearly 3.2 million tons of olive oil was produced worldwide in 2020 . Mediterranean countries such as Spain, Italy, Greece, Portugal, Greece, and Turkey provide 97% of the total olive oil production in the world and represent a major industry in the region. , Olive pomace, a solid byproduct of olive oil production, is nearly 40% of the total weight of olives being processed in the mill . It includes a high concentration of phenolic compounds, and so olive pomace has a high polluting organic load and a phytotoxic effect, and this results in a significant environmental hazard. , Therefore, extraction of phenolic compounds from olive pomace is very important to decrease environmental damage, especially for Mediterranean countries with low-cost sources and with beneficial human physiological actions. , …”