Alginate-microencapsulation of Lactobacillus casei and Bifidobacterium bifidum: Performances of encapsulated microorganisms and bead-validation in lamb rennet

Lactobacillus casei Lc01 and Bifidobacterium bifidum Bb02 were loaded in 2%-alginate beads and stored at 4 °C for 1 month. After the storage, some technological and probiotic properties were measured on the cells released from beads. Free cells (microorganisms grown at 30–37 °C for 24 h and immediately used) and cells frozen with a cryoprotective agent (33% glycerol) and stored for 1 month were used as negative and positive controls, respectively. The loading of probiotics in beads did not affect acidification (ΔpH of 1.4–1.6), neither growth index at 15 (15–25%), 45 °C (34–45% for Bb02 and 57–67% for Lc01), at pH 9 (46–57%) or in presence of 3% NaCl (75–88%). Concerning the viability at pH 2.5 and in presence of bile salts, the cells released from beads behaved like free ones (viability loss of 2–3 log cfu/mL for both the strains), while frozen cells experienced a stronger cell decrease (5–6 log cfu/mL). As an additional goal, a validation of beads in a lamb rennet was proposed to design a new kind of rennet with “probiotics in” but protected from the harsh conditions. The strains were released from beads and survived for at least 47–49 days.