Biocatalytic esterification of fatty acids using a low-cost fermented solid from solid-state fermentation with...

Area of Science:

• Biocatalysis and Enzyme Technology
• Renewable Energy Sources
• Biotechnology

Background:

• Acid raw materials for biodiesel synthesis often contain high levels of free fatty acids (FFAs).
• Efficient esterification of FFAs is crucial for improving biodiesel yield and quality.
• Developing cost-effective and reusable biocatalysts is essential for sustainable biodiesel production.

Purpose of the Study:

• To evaluate a lyophilized fermented solid (solid enzymatic preparation, SEP) with lipase activity as a low-cost biocatalyst.
• To investigate the esterification of major fatty acids (oleic, linoleic, stearic, palmitic) using SEP for biodiesel synthesis.
• To assess the reusability and stability of the SEP biocatalyst over multiple reaction cycles.

Main Methods:

• Solid-state fermentation (SSF) of soybean bran using *Yarrowia lipolytica* IMUFRJ 50682 to produce SEP.
• Esterification reactions of ethanol with oleic, linoleic, stearic, and palmitic acids using SEP under various conditions.
• Investigating reaction parameters including SEP concentration, molar ratio, temperature, and solvent presence.
• Assessing SEP reusability through ten successive batches with different washing solvents (ethanol, water, n-hexane).

Main Results:

• High conversion rates (>85% for oleic acid, >79% for stearic, >82% for palmitic, >90% for linoleic) were achieved within 24 hours.
• Effective esterification was observed both with and without a solvent (n-hexane).
• Washing the SEP with water enabled reuse for six cycles while maintaining over 80% of the initial conversion efficiency.

Conclusions:

• The solid enzymatic preparation (SEP) is a promising, low-cost biocatalyst for the esterification of fatty acids in acid oils for biodiesel production.
• SEP exhibits significant potential for application across a wide range of raw materials due to its effectiveness and reusability.
• The use of water washing for SEP regeneration enhances its sustainability and economic viability in industrial biodiesel synthesis.