Preparation of Modified Starch-Based Silver Carp Oil Pickering Emulsion and Its Physicochemical Properties

In order to improve the utilization rate of silver carp fat, a by-product of silver carp surimi processing, the modified starch-based Pickering emulsion was prepared with six modified starches as solid particles and silver carp oil as oil phase. The effects of starch type, starch amount (1%, 2%, 3%, 4%, 5%, w/w), oil-to-water ratio (0.1, 0.2, 0.3, 0.4, 0.5, 0.6, w/w) and ionic strength (NaCl concentration: 0, 0.1, 0.2, 0.3, 0.4, 0.5 mol/L) on the emulsion physicochemical properties (including particle size, Zeta potential, emulsifying properties, stability, rheological properties, and microstructure) were investigated. The results showed that, among the six modified starches, the octenyl succinic anhydride modified corn starch had the smallest particle size (146.73 nm) and the largest contact angle (71.5°), and its Pickering emulsion had the best stability. The oil-water ratio and starch amount significantly affected the physiochemical properties of the prepared emulsion, and the emulsion had gel properties at the higher level of oil-water ratio (0.5~0.6) and starch amount (4%~5%). The addition of an appropriate amount (0.3~0.5 mol/L) of sodium chloride could promote the micro-flocculation of the emulsion and enhance the stability of the emulsion. The emulsion microstructure observed by confocal laser microscopic (CLSM) revealed that the particle size of the emulsion droplets decreased with the increase of starch amount, and the oil droplets were completely wrapped by modified starch particles and formed a dense interfacial film at the addition of 2%~5% starch. In conclusion, the better performance of Pickering emulsion was achieved at the oil-water ratio 0.5, starch amount 4% and sodium chloride concentration 0.4 mol/L, respectively. The study provides a reference for the preparation of fish oil Pickering emulsion and improves its application in functional food.