Sequential extraction of value-added bioproducts from three Chlorella strains using a drying-based combined...

Area of Science:

• Biotechnology
• Biochemistry
• Phycology

Background:

• Microalgae are a promising source of valuable biochemicals.
• Efficient extraction methods are crucial for realizing the economic potential of microalgae.
• Sequential extraction offers a practical approach for large-scale bioproduct recovery.

Purpose of the Study:

• To investigate the impact of drying methods (freeze-drying vs. oven-drying) on the sequential extraction of biochemicals from microalgae.
• To compare the efficiency of freeze-drying and oven-drying for extracting lipids, carbohydrates, and proteins.
• To assess the overall economic potential of microalgae as a feedstock using a mass balance approach.

Main Methods:

• Sequential extraction of biochemicals from three microalgae strains (Chlorella sorokiniana IG-W-96, Chlorella sp. PG-96, and Chlorella vulgaris IG-R-96).
• Combined cell disruption techniques including drying, grinding, organic solvent treatment, and ultra-sonication.
• Comparative analysis of freeze-dried and oven-dried samples to evaluate the effect of drying on extraction yields.
• Transmission Electron Microscopy (TEM) to assess cell wall strength variations.

Main Results:

• Freeze-dried samples generally showed higher total ash-plus content of biochemicals compared to oven-dried samples, particularly for Chlorella vulgaris IG-R-96.
• Lipid, carbohydrate, and protein yields were consistently higher in freeze-dried microalgae compared to oven-dried samples.
• Differences in biochemical content among strains were attributed to variations in cell wall strength, as confirmed by TEM imaging.
• Total mass balance indicated that drying-based sequential extraction better reflects the economic viability of algal feedstock.

Conclusions:

• Freeze-drying is a superior method to oven-drying for enhancing the sequential extraction of multiple biochemicals from microalgae.
• The strength of the microalgal cell wall significantly influences the efficiency of biochemical extraction.
• Sequential extraction coupled with optimized drying techniques presents a viable strategy for the sustainable and economic utilization of microalgal biomass.