title: Packaging gas selects lactic acid bacterial communities on raw pork.
abstract: OBJECTIVE
  To study the effect of different CO2-rich packaging atmospheres on the composition of lactic acid bacterial communities proliferating on raw pork.
  
  
  RESULTS
  Raw pork loin was inoculated with a mixture of 14 lactic acid bacteria (LAB) strains previously associated with meat and packaged with four gas atmospheres: (i) 100% CO2 (ii) 80% N2 20% CO2 (iii) 80% N2, 20% CO2, 0·4% CO and (iv) 80% O2, 20% CO2. The colony counts of LAB, pH and composition of packaging gas were monitored every other day during the storage of 14 days at +6°C. The compositions of lactic acid bacterial communities on pork were evaluated after 7 days of storage with culture-independent, terminal restriction fragment length polymorphism analysis of 16S rRNA gene fragments. After 14 days of storage, the compositions of lactic acid bacterial communities were evaluated using identification of plate-grown LAB isolates by numerical ribopattern analysis. The results showed that (i) high concentration of CO2 in packaging atmosphere favoured Lactobacillus sp. (ii) high concentration of O2 favoured Leuconostoc spp. (iii) atmosphere with 80% N2, 20% CO2 favoured Lactococcus sp.
  
  
  CONCLUSIONS
  The composition of modified packaging atmosphere is a major factor selecting lactic acid bacterial communities proliferating on raw meat.
  
  
  CONCLUSIONS
  The study provides an explanation for the compositions of lactic bacterial communities on modified atmosphere packaged raw meat observed in other studies. The results should be considered when attempting to manipulate LAB communities in raw meat, e.g. by protective cultures.
authors.affiliation: Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland.|Ruralia institute, Faculty of Agriculture and Forestry, University of Helsinki, Seinäjoki, Finland.
authors.forename: T T
authors.initials: TT
authors.lastname: Nieminen
authors.affiliation: Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland.
authors.forename: M
authors.initials: M
authors.lastname: Nummela
authors.affiliation: Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland.
authors.forename: J
authors.initials: J
authors.lastname: Björkroth
mesh_terms: D000818:Animals; D001272:Atmosphere; D015169:Colony Count, Microbial; D005506:Food Contamination / Q000032:analysis; D018857:Food Packaging / Q000295:instrumentation / Q000379:methods*; D019344:Lactic Acid / Q000378:metabolism; D056546:Lactobacillales / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification / Q000378:metabolism*; D008460:Meat / Q000382:microbiology*; D012150:Polymorphism, Restriction Fragment Length; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D013552:Swine
chemical_list: D012336:RNA, Ribosomal, 16S; D019344:Lactic Acid
keywords: Lactobacillus; Lactococcus; Leuconostoc; lactic acid bacteria; meat; modified atmosphere; pork; spoilage