Aims: Response surface methodology (RSM) was used to optimize a protective medium for enhancing the viability of Lactobacillus rhamnosus E/N cells during lyophilization.
Methods and results: Spirulina, sucrose and lactulose were selected, on the basis of a Plackett-Burman factorial design, as important protectants having the following protective effects on cell viability: 102.025, 36.885 and -34.42, respectively. A full-factorial central composite design was applied to determine optimal levels of three used agents.
Conclusion: The optimal protective medium composition was determined to be: Spirulina 1.304% (w/v), lactulose 5.48% (w/v), and sucrose 13.04% (w/v) (Polish Patent P-393189). The predictive value of cell viability in this medium was 89.619%, and experimental viability obtained during freeze-drying was 87.5%.
Significance and impact of the study: In this study, Spirulina was used for the first time as the protective agent in freeze-drying medium, significantly increasing lactobacilli viability and giving synbiotic character of the final product.
© 2011 The Authors. Letters in Applied Microbiology © 2011 The Society for Applied Microbiology.