Encapsulation of living bifidobacteria in ultrathin PVOH electrospun fibers.

This study shows the application of the electrospinning technique as a viable method for the encapsulation and stabilization of bifidobacterial strains. Poly(vinyl alcohol) (PVOH) was used as the encapsulating material because it is generally recognized as safe (GRAS), has a high oxygen barrier when dry, and is water soluble, hence allowing easy recovery of the bacteria for viability testing. A coaxial setup was used for encapsulation, and the so-obtained electrospun fibers had a mean diameter of ca. 150 nm. Incorporation of B. animalis Bb12 led to a decrease in melting point and crystallinity of the PVOH fibers and to an increase in the polymer glass transition temperature. The viability tests, carried out at three different temperatures (room temperature and 4 and -20 degrees C) showed that B. animalis Bb12 encapsulated within the electrospun PVOH fibers remained viable for 40 days at room temperature and for 130 days at refrigeration temperature, whereas a significant viability decrease was observed in both cases when bacteria were not encapsulated (p = 0.015 and p = 0.002, respectively).