Abstract:
Bifidobacteria have been efficiently encapsulated in poly(vinylpyrrolidone)-poly(vinylacetate-co-crotonic acid)
(PVP:PVAc-CA) interpolymer complex formed in scCO2. Research indicated that this method improves the
stability of encapsulated bacteria in simulated gastrointestinal fluids in vitro. However, further analysis indicated
release of lower numbers of encapsulated bacteria from the encapsulating matrix. The aims of this study were to
determine a method that would release high numbers of bacteria from the PVP:PVAc-CA interpolymer complex
matrix microparticles, and furthermore, to determine the effects of milling on the morphological properties of the
microparticles. Three release methods, namely sonication, homogenization in a stomacher and incubation in
simulated intestinal fluid (SIF) were compared. Released viable bacteria were assayed using plate counts. Viable
bacteria released using a stomacher were three orders of magnitude higher than those released by incubation and an
order of magnitude higher than those released using sonication. SEM indicated no negative effects such as exposure
of encapsulated bacteria on the matrix due to milling of product. Homogenization in a stomacher is the most
efficient method for releasing bacteria from the PVP:PVAc-CA interpolymer complex matrix. Particle size of the
PVP:PVAc-CA microparticles encapsulating bacteria can be reduced further by grinding, without exposing the
enclosed bacteria.
