Effects of sodium alginate on microstructural and properties of bacterial cellulose nanocrystal stabilized emulsions

In this work, we reported the in situ biological modification of bacterial cellulose (BC) using various sodium alginate with different molecular weights as the carbon source in the fermentation media. The presence of sodium alginate (SA) showed a great influence on the microstructure of the resulting components of bacterial cellulose incorporated with sodium alginate (SA-BCs), based on the characterization results of SEM images, FT-IR analysis, crystallinity index, and contact angles. With the addition of high molecular weight of SA, the resulting high molecular weight of SA and BC composite (H-SA-BC) demonstrated a narrower fiber and less intramolecular hydrogen bonds, as compared to the modified BCs with lower molecular weights. Specifically, the crystallinity index value of SA-BCs was observed to decrease with the increase of SA’s molecular weight. Using these SA-BCs as emulsifiers, the corresponding physicochemical properties and emulsifying performances of BC and SA-BCs in the stabilization of olive oil Pickering emulsion were fully assessed by Optical micrographs, the diameter of droplets and CLSM images. SA-BCs were proven to show stronger amphipathicity as compared to BC due to the lower molecular regularity of SA-BC and the presence of carboxyl groups. The droplets of the emulsions are observed to be smaller and more uniform when stabilized by the emulsifier of H-SA-BC. Therefore, the addition of SA in the biological modification of BC resulted in a great change in both morphology and amphiphilicity. These results would be helpful in the understanding of the development of natural materials as stabilizers for the potential applications of Pickering emulsions.