The suspended cultures of B. bifidum Bb-12 or L. casei-01 were
centrifuged at 3000 g for 5 min at 4 C to obtain concentrated
cells (w1010 cfu g1
). Concentrated cells were microentrapped by
mixing one part of cells with four parts sodium alginate (3%, w/v)
according to Sheu and Marshal (1993). Fifty mL of the mixture was
added dropwise to 250 mL of vegetable oil containing Tween 80
(0.2%, w/v); this mixture was stirred at 200 rpm by magnetic stirring.
Within 10 min, a uniformly turbid emulsion was obtained
with no evidence of a free aqueous phase. Calcium chloride
(w500 mL, 0.05 M) was added quickly but gently (20 mL s1
) down
the side of the beaker until the water/oil emulsion was broken.
Calcium alginate beads were formed within 10 min. The beads
(w108 cfu g1
) were collected by gentle centrifugation (350 g for
10 min at 4 C) and washed with sterile water.