A Structural Study on Canola Oil-Fermented Microbial Emulsions Using Rhodococcus koreensis BT1 Strain

Area of Science:

• Biochemistry
• Materials Science
• Colloid and Surface Chemistry

Background:

• Growing demand for sustainable bioderived surfactants.
• Limited research on the structure of microbial surfactant-stabilized emulsions.
• Need for understanding complex interfacial phenomena in biosurfactant systems.

Purpose of the Study:

• To characterize a novel microbial emulsion produced by fermenting canola oil with the BT1 strain.
• To investigate the structure and interfacial properties of the biosurfactants and resulting emulsions.
• To explore the origins of interfacial patterns observed in polarized optical microscopy.

Main Methods:

• Fermentation of canola oil with BT1 strain.
• Relaxation nuclear magnetic resonance (NMR) and pendant drop tensiometry for interfacial activity.
• Reflective polarized optical microscopy (POM) for droplet structure analysis.
• Cryogenic scanning electron microscopy (Cryo-SEM) for interface morphology.
• Differential scanning calorimetry (DSC) for thermal behavior.

Main Results:

• Fermentation products act as biosurfactants, forming stable water-in-oil-in-water (W/O/W) emulsions via spontaneous phase inversion.
• Observed interfacial coloration and patterns in POM, distinct from typical liquid crystal emulsions.
• Cryo-SEM indicated adsorption of interface-active substances at water-oil interfaces.
• DSC revealed influence on water and canola oil melting/crystallization, enhancing refrigeration stability.

Conclusions:

• The study presents a novel microbial emulsion with unique structural and interfacial characteristics.
• Demonstrated biosurfactants capable of forming W/O/W emulsions without complex processing.
• Highlighted the need for careful interpretation of POM patterns, as they do not always indicate liquid crystallinity.
• The microbial emulsion exhibits enhanced refrigeration stability due to the biosurfactants' influence on thermal properties.