Anti- activity of subsp. LAB3 cells entrapped in alginate beads: effects of inoculum size, alginate bead formulation, and atmosphere composition.

Bioprotective LAB3 cells that produce bacteriocin-like substances were entrapped in 4% (w/w) sodium alginate matrices, either with or without 10% (w/w) sodium caseinate. The effects of bead formulation-alginate alone or combined with caseinate, with or without the addition of 20% (w/w) MRS broth or M17 broth-on the culturability of LAB3 cells within the beads and their anti activity were assessed over 12 days of storage at 30 °C in closed bottles. Calcium-alginate-caseinate beads supplemented with MRS broth proved most effective in preserving both culturability and anti- activity. Inoculum size (~10 or ~10 CFU mL initially) also played a role: only the higher initial inoculum yielded significant anti- activity after 12 days at 30 °C, despite a gradual decline over time, likely due to rapid nutrient depletion. In order to evaluate the feasibility of combining modified-atmosphere packaging with the addition of the LAB3 bioprotective strain for preserving perishable foods, a prerequisite was to evaluate whether anti- activity persisted after 4 days of storage at 30 °C in calcium-alginate-caseinate beads containing either MRS or M17 broth under three different atmospheres. Beads entrapping LAB3 cells stored in 20% (v/v) O-80% (v/v) N or in 60% (v/v) O-40% (v/v) N retained their anti- activity, whereas storage in 20% (v/v) CO-80% (v/v) N impaired this activity.