Olive Mill Waste Seen as a Renewable Resource for Biosurfactant Production

Researchers have discovered an innovative, cost-effective and environmentally viable process to recycle olive oil waste byproduct into valuable biosurfactants.

Olive oil production plant in Cordoba, Spain
Aug. 3, 2016
By Negar Jamshidi
Olive oil production plant in Cordoba, Spain

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The Mediterranean region, includ­ing Spain, Italy, Greece and Tunisia, pro­duces the vast major­ity of world’s olive oil which con­se­quently gen­er­ates large amounts of pol­luted waste dur­ing the pro­duc­tion process.

Researchers are actively seek­ing strate­gies to reduce the vast quan­ti­ties of olive mill byprod­uct that is both envi­ron­men­tally and eco­nom­i­cally viable. Spain as the largest pro­ducer of olive oil has been espe­cially focus­ing efforts on low­er­ing this waste bur­den and its impact on the envi­ron­ment.
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During the extrac­tion phase, a paste known as alpe­orujo or olive mill waste (OMW) is pro­duced. This solid waste is a rich source of polyphe­nols which exhibit antimi­cro­bial activ­ity and thereby inhibit fur­ther bio­log­i­cal recy­cling. Currently, alpe­orujo is used for energy pro­duc­tion which is not pro­duc­tive or cost-effec­tive.

Alpeorujo also has high amounts of lig­no­cel­lu­losic mate­r­ial, resid­ual oil and min­er­als suit­able as a car­bon source for bac­te­ria growth.

Biosurfactants (BS) are bio­log­i­cal and biodegrad­able sur­face active mol­e­cules pro­duced through fer­men­ta­tion into var­i­ous chem­i­cal struc­tures such as gly­col­ipids, fatty acids and phos­pho­lipids. They are also supe­rior alter­na­tives to syn­thetic sur­fac­tants due to opti­mal sta­bil­ity and per­for­mance under extreme envi­ron­men­tal con­di­tions.

The use of these com­pounds in soil con­di­tion­ing, food, med­i­cine and phar­ma­ceu­ti­cal indus­tries have fur­ther added infi­nite value as an envi­ron­men­tally viable replace­ment to the chem­i­cally pro­duced sur­fac­tants.

However, the high devel­op­ment costs are a draw­back on the large-scale indus­trial pro­duc­tion of bio­sur­fac­tants and con­sid­er­able process opti­miza­tion is required to ensure eco­nomic sus­tain­abil­ity.

One strat­egy employed by agri­cul­ture and food indus­tries is to use waste prod­ucts such as waste oils, fatty acids and glyc­erol as a car­bon source by fer­men­ta­tion to reduce asso­ci­ated pro­duc­tion costs.

This idea led a col­lab­o­ra­tive group of researchers from Spain and Ireland to the inno­v­a­tive use of car­bon-rich alpe­orujo in the pro­duc­tion of bio­sur­fac­tants through fer­men­ta­tion sub­strates Pseudomonas aerug­i­nosa and Bacillus sub­tilis bac­te­r­ial species.

In a ground­break­ing twist, the same research groups demon­strated that hydrol­y­sis pre­treat­ment of the OMW sig­nif­i­cantly increased bioavail­abil­ity of the sug­ars present in alpe­orujo result­ing in marked improve­ment in bio­sur­fac­tants pro­duc­tion.

The sci­en­tists found that com­pared to acid or acid-enzy­matic pre­treat­ment, the high­est yield of sur­fac­tant was pro­duced by enzy­matic hydrol­y­sis pre­treat­ment of the waste by-prod­uct.

The group also showed that the use of OMW as the sole car­bon source is sim­i­lar to that of glu­cose for bio­sur­fac­tant pro­duc­tion, indi­cat­ing large scale BS pro­duc­tion achiev­able at a lower cost and a more effi­cient sub­strate.

Furthermore, the pro­duc­tion of bio­sur­fac­tants was not only sig­nif­i­cantly improved with increased con­cen­tra­tion of OMW, but there was also a faster turn-around with the hydrolyzed pre­treat­ment process.

The sci­en­tists con­cluded that an appro­pri­ate hydrol­y­sis pre­treat­ment is a key fac­tor for a poten­tial indus­trial pro­duc­tion of bio­sur­fac­tant from OMW.”

The researchers noted that while many agroin­dus­trial residues demand some kind of phys­i­cal pre­treat­ment before the hydrol­y­sis stage, OMW is already ground, so its use will avoid this energy-inten­sive step. This imparts a great advan­tage over other lig­no­cel­lu­losic agroin­dus­trial wastes in a future devel­op­ment of a cost effec­tive BS pro­duc­tion process.”



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