Valorization of Olive Mill Wastewater by Selective Sequential Fermentation.

Area of Science:

• Biotechnology
• Food Science
• Environmental Science

Background:

• Olive mill wastewater (OMW) is a major by-product of olive oil production, posing environmental challenges due to its high organic load.
• Effective management strategies for OMW are crucial to mitigate its environmental impact and explore potential resource recovery.

Purpose of the Study:

• To valorize olive mill wastewater by converting it into acetic beverages with reduced or no alcohol content.
• To investigate the production of acetic and gluconic acids from OMW using selective fermentation processes.

Main Methods:

• Olive mill wastewaters were subjected to alcoholic fermentation using *Saccharomyces cerevisiae*.
• The resulting alcoholic substrate was then fermented for acetic acid production by *Acetobacter pasteurianus* in static and submerged systems.
• Chemical analyses were performed to quantify organic acids and assess antioxidant activity.

Main Results:

• Static acetification resulted in no residual ethanol and high concentrations of acetic acid (46.85 g/L) and gluconic acid (44.87 g/L).
• Submerged fermentation yielded 31.63 g/L acetic acid and 39.90 g/L gluconic acid, with a residual ethanol concentration of 24.74 g/L.
• Fermentation processes were found to enhance the antioxidant properties of the olive mill wastewater.

Conclusions:

• Selective fermentation offers a viable pathway for the valorization of olive mill wastewater into functional acetic beverages.
• The study demonstrates the potential for producing high-value organic acids and improving the antioxidant capacity of OMW.
• These findings highlight a sustainable approach to managing olive mill wastewater while creating valuable food products.