engleski

Green solvents for the extraction of olive pomace phenolics

Olive pomace, a by-product of the olive oil production, represents a serious ecological problem in Mediterranean region. Olive pomace is a dark-coloured waste that contains high amounts of organic materials that are not easily degradable or can even be toxic to plant life. But some of these compounds, like phenolic compounds, can act as potent natural antioxidants with bioactive activities. Olive pomace is a great source of phenolic alcohols, phenolic acids, flavonoids, lignans and especially secoiridoids, specific phenolic compounds of the Oleaceae family plants. The removal of the phenolics can facilitate further processing of the pomace and extracted compounds could be used as antioxidants in different food systems or as nutraceuticals. Nowadays new technologies and new generation of solvents are investigated in order to reduce environmental impact by increasing efficiency and sustainability of the extraction process. That is why the aim of this research was optimization of the method for the extraction of phenolic compounds from olive pomace using natural deep eutectic solvents and microwaves and/or ultrasound. We tested several green solvents with choline chloride or betaine chloride as hydrogen acceptor and various hydrogen-bond donors (sugars, alcohols ad carboxylic acids). Of eighth different natural deep eutectic solvents tested in our research, choline citrate was found to be most effective. Selected solvent was further used for the optimization of extraction process using and an ultrasonic-microwave cooperative reactor. Results have showed that microwave assisted extraction is the method of choice for the isolation of phenolic compounds from olive pomace. Longer extraction time and higher power used have positive impact on the extractability. Optimal extraction parameters are 30% water in the solvent, 12 minutes extraction time, and microwave power 300 W. Using microwave assisted extraction of phenolic compounds with selected parameters resulted in reduction of extraction time by 92% and increase of phenolic yield for 28% when compared to conventional methanol extraction method.

natural deep eutectic solvents ; microwave ; olive pomace ; phenolic compounds ; ultrasound

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