Volatile and non-volatile profiles of olive pomace and its potential uses

Olive pomace is an environmentally harmful waste from the olive oil industry, containing large amounts of bioactive compounds that could be used in several areas. In the present study, the olive pomace, by-products, was fractionated successively using organic solvents of increasing polarity (cyclohexane (CYHA), ethanol (EtOH) and distilled water) to determine their biochemical composition (total phenolic content, total flavonoid content, HPLC, and GC-MS) and biological activities (antioxidant and antibacterial activities). In addition, the olive pomace was extract directly by the distilled water to determine its physicochemical characteristics (pH, humidity and quantity of oil). The study proved that olive pomace has a low content of total phenolic content in the three extracts (from 0.81 to 2.24 mg GAE/g dry residue). Likewise, for the content of total flavonoids, it presents in the CYHA and EtOH extracts of 0.5 and 0.4 mg QE/g dry residue, respectively. GC-MS data showed the detection of 6 volatile compounds in the cyclohexane extract which contains two major compounds were hexadecanoic acid (2.23%) and 9-octadecenoic acid (8.67%). Moreover, HPLC data showed that chrysin compound was the major one among the four detected ones in the organic extracts of olive pomace. The results showed that the CYHA extract exhibited the best antioxidant power exceeds 50% on the other hand, it is less than 25% for the ethanoic and aqueous extract. In the aqueous extract there is a stronger antibacterial activity against the strain L. monocytogenes (13 mm) than the reference (ampicillin) and the bacterial strain B. cereus (11 mm) associated with their phenolic activity.