Soy Protein Isolate-Alginate Microspheres for Encapsulation ofEnterococcus faecalis HZNU P2

Abstract

ABSTRACTIn this work, the mixture of alginate and soy protein isolate used as a wall material was developed to encapsulateEnterococcus faecalis HZNU P2 (E. faecalis HZNU P2). The survival ability in the simulated gastric fluid (SGF) and bile salt solution, storage stability at different temperatures and release properties in the simulated intestinal fluid (SIF) of encapsulated cells were assessed. The results showed that encapsulation could offer sufficient protection toE. faecalis HZNU P2. The viability of encapsulatedE. faecalis HZNU P2 did not decrease in SGF at pH 2.5 or 2.0 after 2 h incubation, while free cells were reduced from 11 to 9.85 log CFU/mL in SGF (pH 2.5) at the same exposure time. Only minor viability of encapsulatedE. faecalis HZNU P2 lost in 1.0 or 2.0% bile salt solution for 1 or 2 h exposure, compared with no survival of freeE. faecalis HZNU P2 under the same conditions. EncapsulatedE. faecalis HZNU P2 was completely released from the microspheres in SIF within 1 h. The viability of encapsulatedE. faecalisHZNU P2 stored for two weeks at 4°C was fully retained. Viabilities of encapsulatedE. faecalis HZNU P2, 9.6 and 9.0 Log CFU/g were obtained at 25 and 37°C after 21 days storage, respectively. However, around 1.0 log CFU/mL of free cells was reduced after two weeks storage at 4°C. EncapsulatedE. faecalis HZNU P2 using soy protein isolate and alginate as wall materials could play an important role in food applications.

Keywords

• Enterococcus faecalis
• Encapsulation
• Soy protein isolate
• Alginate
• Stability
• Viability