Improving stabilising effect of Enterococcus faecalis HZNU S1 microbeads with rice milk and alginate as wall materials

The utilisation of E. faecalis HZNU S1 as a probiotic is hindered by its sensitivity to gastrointestinal and storage environments. Therefore, the aim of the present work was to encapsulate E. faecalis HZNU S1 using alginate (ALG) and rice milk (RM) as encapsulating materials through the extrusion method. The resulting microbeads were characterised in terms of their size, encapsulation efficiency, and probiotic resistance under simulated gastrointestinal conditions, and also with regard to various storage conditions. The microbeads had a mean particle size of 1.60 ± 0.20 mm, and an encapsulation efficiency of 97.40%. The viability of free-state probiotics exposed to simulated gastric juice (SGJ) was found to be poor. After the treatment with SGJ under pH 2.0 and 2.5 for 1.0 h, the viability of encapsulated cells was found to be greater than 6.0 log CFU/g. Furthermore, encapsulation led to an enhancement in the viable rate of cells when incubated in bile salt solution. After exposure to bile salt solution (0.30%), the viable count entrapped cells significantly decreased from 10.01 to 6.92 log CFU/g after 1 h of exposure. The full release of entrapped cells was observed when exposed to simulated intestinal juice (SIJ) within 120 min. Furthermore, encapsulation also was able to improve the storage stability of probiotics. After 12 days of storage, viable counts of encapsulated cells were 9.1 and 6.3 log CFU/g at 4 and 25°C, respectively. Therefore, the present work suggested that encapsulating E. faecalis HZNU S1 within ALG/RM microbeads could enhance its survival during both gastric-intestinal tract and storage conditions.