Method for the preparation of stabile microencapsulated lactic acid bacteria

Abstract

A method to produce viable and stabile dry microorganisms for food and agricultural purposes was developed. Spray-dried, freeze-dried or liquid culture concentrates of lactic acid-producing bacteria were mixed with various bulking agents to form a homogeneous wet granulation having a water content of 35–60% (w/w). The wet granulation was extruded through a dye onto a spinning plate (350–500 rpm) of a spheronizing device which resulted in the formation of discrete spherical particles. After forming spheres, the aggregate cell particles, both coated and uncoated, were dried to a moisture level of 5–10% using a temperature below the microorganism's optimum growth temperature. The coated and uncoated products were stored at different temperatures and periodically sampled to determine stability. Uncoated cell particles were more stabile at 4°C than at 22°C for 76 days. While both coated (with sodium alginate or carboxymethyl-cellulose) and uncoated particles showed similar stability at 4°C, at higher storage temperatures the applied coating improved the storage stability of the culture particles.