Summary
Immobilized cell technology was used to prepare concentrated cultures ofLactococcus lactis that lost only 22% of viability over a 30-day storage period at 4°C. Concentrated cultures ofL lactis CRA-1 were immobilized in calcium alginate beads and added to glycerol, NaCl or sucrose-NaCl solutions in order to obtain aw readings ranging from 0.91 to 0.97. The suspensions were subsequently placed at 4°C and viability (CFU g−1 of bead) was followed during storage. Viability losses were high at aw readings of 0.95 and 0.97 and pH dropped significantly (up to one unit) in the unbuffered solutions. Addition of 1% soytone or glycerophosphate helphed stabilize pH, and a beneficial effect on viability during storage was observed in the glycerol-soytone mix when the beads were added to the conservation solutions immediately following immobilization. When beads were added to the conservation solution immediately following immobilization, a 70% drop in cell counts occurred during the first 5 days of incubation. Dipping theL lactis-carrying beads in milk for 2h before mixing with the glycerolsoytone 0.93 aw solution reduced this initial 5-day viability loss. Cultures grown in the alginate beads also had good stability in the 0.93 aw glycerol-soytone solution, where 78% of the population was viable after 30 days at 4°C. The process could be used to store immobilized cells at a processing plant, or by suppliers of lactic starters who wish to ship cultures without freezing or drying.
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Champagne, C.P., Gardner, N. & Dugal, F. Increasing the stability of immobilizedLactococcus lactis cultures stored at 4 °C. Journal of Industrial Microbiology 13, 367–371 (1994). https://doi.org/10.1007/BF01577221
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DOI: https://doi.org/10.1007/BF01577221