Storage-Dependent Stability and Viability of Alginate-Carrageenan Encapsulated Synbiotics in Fish Aquaculture

Despite the growing interest in synbiotic encapsulation, most previous studies have primarily focused on single-strain probiotics or spray-drying techniques, with limited attention given to extrusion-based alginate–carrageenan systems under practical storage conditions. This study aimed to evaluate the effect of storage temperature and periods on the viability and physicochemical stability of encapsulated synbiotics based on an alginate–carrageenan matrix. The encapsulated synbiotics were produced using an extrusion method with a 21G needle size. The experiment employed a factorial completely randomized design consisting of storage temperature (4 °C and 25 °C) and storage periods (0, 20, 40, and 60 days). The observed parameters included the viability of probiotic consortium bacteria, encapsulation efficiency (EE), moisture content, water activity (a_w), and color profile (L*, a*, b*, and whiteness). The results showed that storage temperature and periods significantly affected all observed parameters. Viability remained above 10⁶ CFU g^-1 after 60 days under both conditions, with only a 2.79% reduction at 4 °C. Storage at 4 °C was more effective in maintaining probiotic viability and EE values, showing relatively small reductions and remaining above the minimum functional threshold. In contrast, storage at 25 °C resulted in a greater decline in the viability of the probiotic consortium bacteria, accompanied by an increase in moisture content, changes in a_w, and color darkening due to pigment degradation. Overall, the alginate–carrageenan encapsulation system was able to maintain synbiotic stability for up to 60 days, with 4 °C identified as the most optimal storage condition to support the development of applicable and sustainable functional feed. This study contributes to SDG 14 (Life Below Water), SDG 2 (Zero Hunger), and SDG 12 (Responsible Consumption and Production) by supporting sustainable aquaculture through stable synbiotic-based functional feed.