Improving the survival of Lactobacillus plantarum FZU3013 by phase separated caseinate/alginate gel beads

The phase separation behavior of mixed solution of caseinate (Cas) and alginate (Alg) was investigated. Lactobacillus plantarum FZU3013 was encapsulated using 4 % Cas/1 % Alg gel beads with a phase-separated structure. The bacteria were predominantly distributed in the Alg-rich continuous phase. The use of 4 % Cas/1 % Alg beads resulted in higher encapsulation efficiency for L. plantarum FZU3013 compared to 1 % Alg beads. After 5 weeks of storage at 4 °C, the viable count in 4 % Cas/1 % Alg beads was 8.3 log CFU/g, which was 1.1 log CFU/g higher than that of the 1 % Alg beads. When 1 % Alg beads of the smallest size were subjected to in vitro digestion, no viable bacteria could be detected at the end of the digestion, whereas the 4 % Cas/1 % Alg beads of the smallest size had a viable count of 3.9 log CFU/g. When the size of the 4 % Cas/1 % Alg beads was increased to 1000 μm, the viable count was 7.0 log CFU/g after digestion. The results of infrared spectroscopy and zeta potential indicated that hydrogen bonding and electrostatic interactions between caseinate and alginate reinforced the structure of the gel beads and improved the protection for L. plantarum FZU 3013.