Fermentative activity and viability of immobilized probiotic starter culture ABY-6 in whey based substrates

Abstract

The aim of this paper was to study fermentative activity by free and immobilized probiotic ABY-6 culture in whey substrate enriched with milk. Viability of free and immobilized probiotic cells in simulated gastrointestinal conditions was evaluated. In order to improve probiotic character of immobilized cells, the influence of beads wall material composition (alginate, alginate beads with cells coated by whey protein and chitosan–coated alginate beads) was examined. The beads were prepared using electrostatic extrusion technique. Alginate cell suspension was added dropwise by a syringe pump into a gelling solution. After 5.5h of fermentation, enumeration of viable cells was performed by determining the number of colony-forming units on MRS agar plates after incubation at 37 ˚C for 48 h using pour plate technique on MRS agar. The results showed that immobilized cells beads have much better potential for survival in gastrointestinal conditions than free cells. Immobilization of probiotic cells in calcium alginate beads coated with chitosan resulted in better survival than both type of non-coated beads in simulated gastrointestinal conditions. These beads can be used to improve preservation of probiotic cells in fermented whey based beverage.