Encapsulation of Enterococcus faecium in hyaluronic acid/gelatin/sodium alginate/protamine improves cell viability and stability.

Probiotics offer significant health benefits, but their survival is often compromised by harsh conditions during food processing. The primary objective of this study was to enhance the viability and stability of Enterococcus faecium 20,420 (Ef-20,420) through physical extrusion and complex coacervation in a composite of hyaluronic acid (HA), gelatin (GL), sodium alginate (SA), and protamine sulfate (PS). The cell viability of Ef-20,420 before and after encapsulation was 8.51 ± 0.09 log CFU/mL and 8.36 ± 0.07 log CFU/mL, respectively, which remained generally stable. The final product can be stored at 4 °C for up to 12 months. The composite microcapsules were determined to be formed by hydrogen bond and electrostatic interaction through different characterization methods. After exposure to SGF, the composite microcapsules showed a viable cell count reduction of only 1.37 ± 0.13 log CFU/mL. With the addition of PS, the sustained release time of the bacteria in SIF was extended by 60 min. Following high-temperature treatment at 80 ± 0.5 °C for 3 min, the protective effect of the composite microcapsules maintaining a viable cell count at 6.58 ± 0.19 log CFU/mL. After 25 days of storage at 4 ± 0.2 °C, the bacterial count in the composite microcapsules decreased from 8.50 ± 0.04 to 7.10 ± 0.12 log CFU/mL. Additionally, the composite microcapsules increased the transmembrane resistance of Caco-2 cells. Therefore, these findings offered new insights for the development of functional probiotic foods.