Mass transfer characterization of gamma-aminobutyric acid production by Enterococcus faecium CFR 3003: encapsulation improves its survival under simulated gastro-intestinal conditions

Gamma-aminobutyric acid (GABA) production
by free and Ca-alginate encapsulated cells of Enterococcus
faecium CFR 3003 was investigated. Mass transfer rates
characterizing the GABA production process using
encapsulated cells were investigated. Experiments were
performed to investigate external film and internal pore
diffusion mass transfer rates. The Damkohler and Thiele
analysis provides a good description of external film and
internal pore diffusion resistances, respectively. The
experiments revealed that the external film effects could be
neglected but the process is affected to the greater extent
by internal mass transfer effects and was found to be the
principal rate-controlling step. Protective effect of encapsulation
on cell survivability was tested under digestive
environment, when challenged to salivary a-amylase,
simulated gastric fluid and intestinal fluid. Viability of
encapsulated cells was significantly higher under simulated
gastro-intestinal conditions and could produce higher
GABA than those observed with free cells. The results
indicate that the Ca-alginate encapsulated probiotics could
effectively be delivered to the colonic site for effective
inhibitory action.