Gelatin Improve Storage Stability of Alginate-Encapsuled Krill Oil Microcapsules

Antarctic krill oil (AKO) is a valuable nutraceutical; however, it is highly susceptible to oxidation. Encapsulation represents an effective strategy to enhance the storage stability of AKO. This study explored a novel approach for encapsulating AKO using sodium alginate (ALG) and gelatin (GLN) to improve its stability, and multiple parameters were systematically evaluated, including oil-loading efficiency, surface oil content, particle size, water activity, and thermal stability. Additionally, core-material retention efficiency, acid value, peroxide value, and anisidine value were measured after accelerated oxidation. The results demonstrated that the optimal encapsulation conditions consisted of an ALG:GLN ratio of 2:1, a 9% CaCl₂ coagulation bath, 750 μm nozzle size, followed by freeze-drying. Under these conditions, the microcapsules achieved an oil-loading efficiency of 62.63% and a surface oil content of 19.21%. The water activity of the microcapsules was 0.516. Thermogravimetric analysis indicated that AKO microcapsules encapsulated with ALG/GLN exhibited higher thermal stability (~300 °C) compared to those encapsulated with ALG alone (~280 °C). When AKO or its microcapsules were subjected to accelerated oxidation at 65 °C, compared to ALG-encapsulation alone, the ALG/GLN encapsulation system significantly reduced the oxidation indicators of the oil, such as acid value (24%), peroxide value (26%), and anisidine value (28%). In conclusion, incorporating GLN into ALG-based microcapsules significantly enhanced the antioxidant capacity of AKO and prolonged its shelf life.