A simple downstream processing protocol for the recovery of lactic acid from the fermentation broth

Area of Science:

• Biochemical Engineering
• Chemical Process Development
• Green Chemistry

Background:

• Lactic acid is a vital platform chemical with diverse industrial applications.
• Effective and economical recovery of lactic acid from fermentation broths remains a significant challenge in downstream processing.
• Current methods often struggle with efficiency, purity, or cost-effectiveness, limiting its broader utilization.

Purpose of the Study:

• To develop and optimize a novel phase partitioning process for the efficient recovery of lactic acid.
• To investigate the use of n-butanol and ammonium sulfate for lactic acid extraction from Lactobacillus pentosus fermentation broth.
• To confirm the purity and characteristics of the recovered lactic acid and assess its suitability for further applications.

Main Methods:

• A phase partitioning extraction process was designed utilizing n-butanol as the solvent and ammonium sulfate as a chaotropic salt.
• Fermentation broth from Lactobacillus pentosus SKL-18 was used as the source of lactic acid.
• Process parameters, particularly the pH of the extraction medium, were systematically optimized.
• Fourier-transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopy were employed for purity and structural confirmation.

Main Results:

• The optimized process achieved an 86% yield of lactic acid.
• The recovered lactic acid demonstrated a high purity of 93%.
• FTIR and NMR analyses confirmed the identity and purity of the extracted lactic acid.
• The optimal pH for extraction was determined to be 2.5.

Conclusions:

• The developed solvent-based extraction procedure offers an economical and straightforward downstream process for lactic acid purification.
• This method is suitable for lactic acid derived from agro- and bakery-residues.
• The high-purity lactic acid obtained is suitable for the enzymatic synthesis of polylactic acid (PLA), a valuable biodegradable plastic.