Scientists have found a way to turn the waste alperujo by-product from olive oil production into bio-surfactants and monoglycerides, the first time alperujo has been used to produce an eco-friendly surfactant, UPI reported on 15 July.

Alperujo is the main waste by-product of the two-phase method of olive oil extraction, in which no water is added. It is a combination of liquid and solid waste with a thick sludge-like consistency that contains 80% of the olive fruit, including skin, seed, pulp and pieces of stones.

In Spain, over 90% of olive oil mills operate with the two-phase method, which means that annual production of this by-product is around 2.5M tonnes depending on the season (Aragon et al, 2000), posing a serious pollution problem.

The UPI report said that currently, most alperujo is used to make biofuels, but the process was not that efficient or lucrative.

However, scientists at Spain’s University of Granada and Ireland’s University of Ulster found that alperujo successfully fuelled the synthesis of valuable surfactants when fermented along with biosurfactant-producing microorganisms such as Bacillus subtilis and Pseudomonas aeruginosa.

“Researchers believe the new process can produce bio-surfactants more cheaply than current production methods,” the UPI report said.

Surfactants are active surface agents that are used to lower the surface and interfacial tension between two liquids or between a liquid and a solid. They can be used as detergents, wetting agents, emulsifiers, foaming agents and dispersants.

The research, ‘Hydrolysis of olive mill waste to enhance rhamnolipids and surfactant production’, was published in the April 2016 edition of Bioresource Technology.