DELAYING TOXIGENESIS OF CLOSTRIDIUM-BOTULINUM BY SODIUM LACTATE IN SOUS-VIDE PRODUCTS

The effect of sodium lactate and storage temperature on toxigenesis by proteolytic (Pr) and nonproteolytic (Np) Clostridium botulinum spores inoculated in processed 'sous-vide'-type beef, chicken breast and sal mon was explored. Three g samples of beef and salmon homogenates with 0, 2.4 and 4.8% (w/w) lactate and of chicken with 0, 1.8 and 3.6% (w/w ) lactate were placed in 24-well tissue culture plates. The samples we re inoculated with 10(4) spores of pools of Pr (4A + 2B + 2F strains) or Np (4B + 4E strains), vacuum-packaged in barrier bags, and stored a t 16 and 30 degrees C for Pr and at 4, 8, 12 and 30 degrees C for Np f or up to 90 d. Lactate at greater than or equal to 2.4% in beef and gr eater than or equal to 1.8% in chicken delayed toxigenesis by Np for g reater than or equal to 40 d at less than or equal to 12 degrees C and by Pr for greater than or equal to 28 d at less than or equal to 16 d egrees C. Delaying toxigenesis for similar periods of time in salmon r equired 4.8% lactate and less than or equal to 12 degrees C for Np, an d 2.4% lactate and less than or equal to 16 degrees C for Pr. Increasi ng levels of lactate and decreasing temperature significantly delayed toxigenesis of CI. botulinum in the 'sous-vide' products.