title: Behavior and viability of spontaneous oxidative stress-resistant Lactococcus lactis mutants in experimental fermented milk processing.
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); V(max) values were inversely proportional to fermentation time. Bacterial counts increased to above 8.50 log(10) 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 4 degrees C; they remained stable after one week of storage.
authors.affiliation: Departamento de Tecnologia Farmacêutica e Bioquímica, Universidade de São Paulo, São Paulo, SP, Brasil. monolive@usp.br
authors.forename: M N
authors.initials: MN
authors.lastname: Oliveira
authors.forename: K E
authors.initials: KE
authors.lastname: Almeida
authors.forename: M R
authors.initials: MR
authors.lastname: Damin
authors.forename: T
authors.initials: T
authors.lastname: Rochat
authors.forename: J-J
authors.initials: JJ
authors.lastname: Gratadoux
authors.forename: A
authors.initials: A
authors.lastname: Miyoshi
authors.forename: P
authors.initials: P
authors.lastname: Langella
authors.forename: V
authors.initials: V
authors.lastname: Azevedo
mesh_terms: D000143:Acids; D000818:Animals; D015169:Colony Count, Microbial; D043302:Cultured Milk Products / Q000382:microbiology; D005285:Fermentation; D005511:Food Handling; D013294:Lactococcus lactis / Q000166:cytology*; D050296:Microbial Viability; D008892:Milk / Q000382:microbiology*; D009154:Mutation / Q000235:genetics*; D018384:Oxidative Stress; D013696:Temperature
chemical_list: D000143:Acids