Microencapsulation of Lactococcus lactis subsp. cremoris

Lactococcus lactis subsp. cremoris was microencapsulated within alginate/poly-L-lysine (alg/PLL), nylon or crosslinked polyethyleneimine (PEI) membranes. Toxic effects were observed with solvents and reagents used in nylon and PEI membrane formation. Alg/PLL encapsulation resulted in viable and active cell preparations which acidified milk at a rate proportional to the cell concentration, but at rates less than that of free cell preparations. At 4 × 108 colony-forming units (cfu/ml milk), encapsulated cells took 17 per cent longer than free lactococci to reduce the pH of milk to 5 5. Similar activities of free and microencapsulated cells may be attained at higher cell concentrations (109 cfu/ml milk). The rate of lactic acid production was approximately 2mmol/h at an encapsulated cell concentration of 4 × 108 cfu/ml.