M.N. Oliveira, K.E. Almeida, M.R. Damin, T. Rochat, J.-J. Gratadoux, A. Miyoshi, P. Langella, V. Azevedo
Published: July 21, 2009
Genet. Mol. Res. 8 (3) : 840-847
DOI: https://doi.org/10.4238/vol8-3gmr635
Cite this Article:
M.N. Oliveira, K.E. Almeida, M.R. Damin, T. Rochat, J.J. Gratadoux, A. Miyoshi, P. Langella, V. Azevedo (2009). Behavior and viability of spontaneous oxidative stress-resistant Lactococcus lactis mutants in experimental fermented milk processing. Genet. Mol. Res. 8(3): 840-847. https://doi.org/10.4238/vol8-3gmr635
About the Authors
M.N. Oliveira, K.E. Almeida, M.R. Damin, T. Rochat, J.-J. Gratadoux, A. Miyoshi, P. Langella, V. Azevedo
Corresponding Author
M.N. Oliveira
E-mail: monolive@usp.br
ABSTRACT
Previously, we isolated two strains of spontaneous oxidative (SpOx2 and SpOx3) stress mutants of Lactococcus lactis subsp cremoris. Herein, we compared these mutants to a parental wild-type strain (J60011) and a commercial starter in experimental fermented milk production. Total solid contents of milk and fermentation temperature both affected the acidification profile of the spontaneous oxidative stress-resistant L. lactis mutants during fermented milk production. Fermentation times to pH 4.7 ranged from 6.40 h (J60011) to 9.36 h (SpOx2); Vmax values were inversely proportional to fermentation time. Bacterial counts increased to above 8.50 log10 cfu/mL. The counts of viable SpOx3 mutants were higher than those of the parental wild strain in all treatments. All fermented milk products showed post-fermentation acidification after 24 h of storage at 4ºC; they remained stable after one week of storage.
Key words: Lactococcus lactis, Oxidative stress, Acidification kinetics, Spontaneous mutants.