Abstract
Olive pomace, a solid residue generated during olive oil production process and a rich source of phenolic compounds, was dried and defatted to obtain a pomace oil rich in monounsaturated fatty acids with 64% oleic acid. The defatted pomace was further treated by ultrasound-assisted extraction (UAE). The optimal phenol extraction conditions of 10 min, 40% amplitude and 4% (w/v) solid:solvent ratio, yielded to 14.70 mg/g total phenols, 2.48 mg/g total flavonoids and 0.924 mmol Trolox/g antioxidant activity. In order to purify valuable biophenols, two polymeric resins (XAD4 and XAD16) and two activated charcoals (NPAC and GAC) were tested as adsorbents using a magnetic stirrer and an incubator shaker. XAD16 (100 g/L) in magnetic stirrer showed the optimal adsorption ratios with 74.36%, 39.25%, 68.79% and 100% for total phenols, hydroxytyrosol, tyrosol and oleuropein, respectively. Desorption using acidified 50% (v/v) ethanol-water at pH = 2.3 proved 57.65% recovery of total phenols, 19.27% of hydroxytyrosol and 45.73% of tyrosol. These results indicate that extraction and selective purification of biophenols from olive pomace can be achieved by the proposed UAE using 50% v/v ethanol-water as solvent, followed by adsorption-desorption stages with the XAD16 polymeric resin.
Highlights
Olive mill wastes are very well known for their significant negative impact on the environment
total phenolic content (TPC) was expressed as milligrams of gallic acid equivalents per gram of olive pomace for phenolic extraction experiments and milligrams of gallic acid equiva lents per liter of olive extract for adsorption-desorption results
The commercial value of olive pomace depends on its oil content, whose composition is similar, but not identical, to that of typical olive oil (Akay et al, 2015)
Summary
Olive mill wastes are very well known for their significant negative impact on the environment. The three-phase system, used in most of the olive oil producing countries including Iran, generates a solid husk, oil, and a huge volume of foul smelling acidic dark liquid called olive mill wastewater (OMWW), while the two-phase system releases a wet olive husk and oil (Gebreyohannes et al, 2016). This last system is the one used mainly in Spain, the leader in olive tree cultivation (Manzanares et al, 2017) where, according to the estimations from FAOSTAT (2021), 2.6 Mha of olive crop were cultivated in 2019, representing 24.5% of total worldwide production. The conversion of olive mill solid wastes can be directed to heat and power production by thermochemical processes (Parascanu et al, 2018), or be upgraded into added-value products by bio chemical/chemical treatments
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
