O/W Pickering Emulsions Stabilized with Cellulose Nanofibrils Produced through Different Mechanical Treatments

Area of Science:

• Materials Science
• Colloid and Surface Chemistry

Background:

• Pickering emulsions offer unique stabilization properties.
• Cellulosic nanomaterials are promising stabilizers due to their amphiphilic nature and high surface area.
• Mechanical treatments like ball milling (BM) and high-pressure homogenization (HPH) are used to produce cellulose nanomaterials.

Purpose of the Study:

• To investigate the efficacy of nanosized cellulosic materials from raw cellulose and tomato pomace in stabilizing oil-in-water (O/W) Pickering emulsions.
• To compare the performance of cellulose nanofibrils produced by BM and HPH treatments.
• To evaluate the impact of mechanical treatment on cellulose properties and emulsion stabilization.

Main Methods:

• Production of cellulose nanofibrils from raw cellulose and tomato pomace using ball milling (BM) and high-pressure homogenization (HPH).
• Characterization of cellulose nanofibrils, including fiber morphology, flexibility, interfacial tension, and viscosity.
• Preparation and stability testing of O/W Pickering emulsions using the different cellulose nanomaterials under various conditions (refrigeration, centrifugation at different pH).

Main Results:

• HPH-treated cellulose nanofibrils exhibited longer fibers, higher flexibility, lower interfacial tension, and higher viscosity compared to BM-treated ones.
• HPH-treated cellulose demonstrated superior emulsion stabilization, effectively limiting coalescence and slowing gravitational separation.
• HPH-treated cellulose formed a 3D network structure in the continuous phase, entrapping oil droplets, while BM-treated cellulose formed a more compact structure.
• HPH-treated tomato pomace showed comparable particle morphology and interfacial tension to HPH-treated cellulose, with slightly lower emulsion stabilization capability.

Conclusions:

• High-pressure homogenization is a more effective method than ball milling for producing cellulose nanofibrils with enhanced emulsion stabilization properties.
• The formation of a 3D network structure by HPH-treated cellulose is crucial for effective Pickering emulsion stabilization.
• Cellulose isolation is not strictly necessary for efficient defibrillation and stabilization using mechanical disruption methods, as demonstrated by tomato pomace.