Flaxseed protein isolate-alginate microbeads as encapsulating agents for enhanced survival of Enterococcus faecalis HZNU S1 during storage and in vitro gastrointestinal conditions

Abstract

This study aimed to study the entrapment of Enterococcus faecalis HZNU S1 using a mixture of flaxseed protein isolate (FPI) and sodium alginate (SA) as an encapsulation agent. The characteristics of free and encapsulated cells during storage and under in vitro gastrointestinal conditions were investigated. The survival rate of encapsulated cells did not decline after 2 h exposure to pH 2.5 simulated gastric juice (SGJ), while viable free probiotics treated at the same conditions, were not found. After encapsulated probiotics were exposed to SGJ pH 2.0 for 2.0 h, the viability decreased from 10.01 to 8.01 Log CFU/g. After exposure to 1.0% and 2.0% bile salt solutions for 2 h, the viable amounts of encapsulated probiotics were still higher 8.0 Log CFU/g, whereas, viable free cells were not observed after treatment at the same conditions. Encapsulated probiotics were fully released from the microbeads in simulated intestinal juice (SIJ) in around 4 h. The viable numbers of encapsulated probiotics were only reduced 0.5 Log CFU/g after two weeks of storage (4 °C), and the viable amounts of encapsulated probiotics were reduced to 8.2 Log CFU/g at 25 °C after eight days of storage. However, the viable amounts of free cells were reduced from 10.01 to 8.8 Log CFU/mL (4 °C), and 4.0 Log CFU/mL (25 °C) during the investigated storage period, respectively. Encapsulated E. faecalis HZNU S1 showed enhanced resistance to environmental conditions, allowing the delivery of probiotics that could be used to increase foods added value.