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Extracting phenolic compounds from 'alperujo' with ecological solvents

Teams from the CSIC and the University of Seville have developed a methodology to extract phenolic compounds from ‘alperujo’ using natural and ecological solvents (NADES) with an acidic base. With this method, non-toxic 'in vitro' extracts are obtained which can be used for agri-food and nutraceutical products, and which have anti-inflammatory, neuroprotective and antimicrobial properties.

A basin with 'alperujo' in the countryside.

The olive pomace pastes known as ‘alperujo’ is a by-product from the two-step process of olive oil extraction. It is consisting of the olive skin, pulp, stone and part of the olive oil.

Alperujo is a serious environmental problem, not only because it is difficult to biodegrade this by-product, but also because millions of tonnes are generated worldwide every year.  It is estimated that out of one tonne of olives, 20% will be oil and the remaining 80% will be alperujo.

According to the International Olive Oil Council (IOC), more than 3 million tonnes of oil were produced worldwide in the 2021-2022 season. This production is concentrated in the countries of the Mediterranean basin, especially in Spain, which is leading producer, and mainly in Andalusia, where more than 25% of the world's olive oil is produced and where around 4 million tonnes of alperujo are generated in an oil year, according to a report by the Junta de Andalucía.

Therefore, the issue is how to recycle a very abundant by-product, in order to avoid its indefinite storage in basins or tanks that are not always well controlled. Nowadays, alperujo is used for numerous purposes, such as biofuel for energy production, as a fertiliser, by incorporating it directly into the soil or after composting. It is also used in animal feed or to obtain bioactive compounds.

The fact is that 98% of the olive's phenolic compounds are retained in alperujo. These phenolic compounds have numerous beneficial effects on health, derived from its antioxidant and anti-inflammatory capacity. The phenolic compounds in olives prevent cardiovascular diseases, diabetes, Alzheimer's disease and cancer, among others. That’s why extracting the phenols from alperujo is an interesting option.

Teams from the CSIC's Instituto de la Grasa and the University of Sevilla have developed a methodology to extract phenolic compounds from fresh alperujo, using natural deep eutectic solvents (known by the acronym NADES, which stands for ‘Natural Deep Eutectic Solvents’) with an acidic base. NADES came into use a few years ago and are a green alternative ('green solvents') to conventional organic solvents.

The NADES used in this process are mixtures of natural and food-grade substances (such as sugars or acids), used for first time in alperujo, and are an effective, safe and environmentally friendly alternative to the organic solvents that are commonly used.

The new methodology is a simple and inexpensive process, wihich enables the obtention of molecules with healthy properties that can be used as nutraceuticals, food additives or organic plant protection products.

"NADES have a low melting point and are very low volatile, so they pollute the atmosphere less. Conventional solvents are volatile and when they evaporate they pollute the air," says CSIC researcher Aránzazu García. "The solvents we use are a new generation of green, safe, low-toxicity, recyclable and cheap solvents. We are working with green chemistry, different from conventional solvents that are toxic, polluting and unsustainable".

"With this method," explains Aránzazu García, "we obtain non-toxic extracts in vitro that can be used in the agri-food industry and in the nutraceutical sector. 

She adds that tests with cell cultures have shown that "the phenolic extracts obtained with NADES have anti-inflammatory activity in vitro and antimicrobial activity”. 

The new methodology is simple and inexpensive process. The obtained molecules with health-promoting properties can be used as nutraceuticals, food additives or organic plant protection products. Once the compounds have been extracted, the remaining by-product (alperujo extracted with NADES) is treated with vermicomposting processes. Afterwards it can be used for agricultural purposes as a fertiliser or organic amendment, thus achieving a process that is close to zero waste in the production of virgin olive oil..

The scientific teams are now looking for companies in the nutraceutical, food or phytosanitary sectors interested in exploiting this technology through a patent licensing contract.


Chelo Quilchano Gonzalo
Vicepresidencia Adjunta
de Transferencia del Conocimiento - CSIC
Tel.: 954 61 15 50
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