Development and characterization of walnut oleogels structured by cellulose nanofiber

Edible oleogels were successfully prepared by cellulose nanofibers (CNFs) as the unique oleogelator through emulsion-templated method at varying CNF concentrations of 0.4–4.0%, without additional thickening agent. The microstructure and physical properties of the oleogels such as oil binding capacity, rheology, texture, thermal and oxidative stability were evaluated, using a variety of tools including confocal laser scanning microscopy, polarizing light microscopy, fourier transform-infrared spectroscopy and X-ray diffractometer. The adsorption and closely packing of CNF crystals on the surfaces of the oil droplets in emulsion decreased the clustering of droplets, and inhibited the oil droplets from destabilization during drying. This formed a more reticulated and denser but less anisotropic network, contributed to a β polymorph of the lipid crystallization. Thus the oil binding capacity and stability of oleogels were greatly enhanced, while stronger gelation strength, higher hardness, lower mobility and opaque appearance of the oleogels were observed. The oil loss of oleogels after processing at cooking temperature of 90 °C was remarkably declined, while the oxidative stability of the oleogels was also improved to a satisfactory level. In summary, these results contributed to a better understanding of the oleogelation in CNF-based oleogels, and benefited the use of healthy walnut oil to develop functional fat products with desired physical properties and oxidative stability.