Oil-in-water Pickering emulsions with Buriti vegetable oil stabilized with cellulose nanofibrils: Preparation, stability and antimicrobial properties

Mauritia flexuosa (Buriti) vegetable oil (OV) has attracted technological interest in various sectors, including pharmaceuticals, food, and beverages, because of its excellent antioxidant activity. The active OV components are fatty compounds, and stability is required for proper application. In this work, we investigated OV-in-water Pickering emulsions stabilized by cellulose nanofibrils (CNF). CNF is sustainable, economically viable, and environmentally friendly, and it is suitable for developing products in an eco-friendly way. The factorial design of experiments (DoE) indicates that the amount of CNF and the homogenization time significantly affect the emulsion, preventing coalescence over 30 days. Fourier-transform Raman spectroscopy (FT-Raman) and Fouriertransform infrared spectroscopy (FTIR) show that CNF stabilizes the OV droplets through induced dipole-dipole interactions and hydrogen bonds. Rheological analysis was relevant to the relationship between internal microstructure strength and viscous flow behavior of the emulsions. A novel approach enabled the identification of the CNF stabilization mechanism in the emulsion system via fluorescence microscopy. Diameter distribution measurements and steady-state rheological tests indicate that the emulsions have good stability at room temperature and suitable steady-state viscosity for food applications and beverage products as they show pronounced shear thinning behavior for cream and lotion skin care products.