Comparison of concurrent and mixed-flow spray drying on viability, growth kinetics and biofilm formation of Lactobacillus rhamnosus GG microencapsulated with fish gelatin and maltodextrin

Abstract

Commercial probiotics cultures are conventionally delivered as freeze-dried powders. Spray drying is a cost-effective alternative for producing dried probiotic cultures. However, concurrent spray drying (CCSD), the preferred drying configuration to produce spray-dried probiotic powders, inactivates significant amounts of viable cells. The study evaluated the effect of freeze drying (FD), CCSD and/or mixed-flow spray drying (MXSD) on the survival, growth kinetics, biofilm formation and physicochemical properties of microencapsulated Lactobacillus rhamnosus GG (LRGG) powders using fish gelatin (FG) and maltodextrin (MD). MXSD showed significantly (P < 0.05) higher production rates (kg/h) of probiotic powders than CCSD and FD. The microencapsulating method significantly (P < 0.05) affected the cell survival (%) of probiotic cells which was 81.02 ± 0.19, 20.88 ± 0.03, and 10.20 ± 0.02 for FD, MXSD and CCSD, respectively. In all cases, microencapsulation did not alter the growth kinetics of probiotic cells. Microencapsulated cells by MXSD showed higher biofilm formation than non-encapsulated cells and the rest of the treatments (P < 0.05). MXSD powders with higher moisture content and particle agglomeration than FD and CCSD. The mean particle size (μm) of FD, CCSD, and MXSD powders were 54.73 ± 1.40, 22.51 ± 0.34, and 10.53 ± 0.06, respectively. These observations strongly suggest that MXSD is a gentler and better spray drying design than CCSD to produce probiotic powders.