Study of the lactic acid bacteria throughout the manufacture of dry-cured lacon (a Spanish traditional meat product). Effect of some additives

摘要

Total aerobic mesophilic microflora (on SPC agar), lactic acid bacteria (on MRS agar) and lactobacilli (on Rogosa agar) were enumerated in samples from the surface and the interior of the pieces throughout the manufacture of six batches of lacon. Three of the batches were made without additives and three with additives (glucose (2 g/kg), sodium nitrite (E_(250)) (125 mg/kg), sodium nitrate (E_(251)) (175 mg/kg), sodium ascorbate (E_(301)) (500 mg/kg), and sodium citrate (E_(331)) (100 mg/kg)). The counts decreased throughout the manufacturing process, particularly after the salting stage. The use of additives did not affect the counts or the evolution of the microbial groups, except for the lactobacilli, which were present in higher numbers in the batches with additives.rnIn four batches (two without and two with additives), from MRS agar and from Rogosa agar plates, 10 colonies were randomly taken from each sampling point of each batch (five from the surface sample and five from the interior sample) and from each culture medium; a total of 224 strains from MRS agar, and 176 strains from Rogosa agar that were identified by classical methods.rnThe MRS agar displayed moderate selectivity for the isolation of lactic acid bacteria, and only 59% of the isolated strains belonged to this microbial group. Homofermentative and facultative hetero-fermentative lactobacilli (particularly Lactobacillus curvatus and Lactobacillus sakei) were the most abundant species isolated on this medium.rnThe selectivity of the Rogosa agar for lactobacilli was extremely high. The species of lactobacilli isolated on this medium at different stages of manufacture of the four batches of lacon were consistent with those isolated from MRS agar.rnThe use of additives in the lacon did not appreciably affect the kinds and proportions of species isolated on either MRS agar or Rogosa agar.