Ecophysiological attributes of a Lactobacillus sp and a Pseudomonas sp on sterile beef fillets in relation to storage temperature and film permeability

Aims: To determine the combined effect of packaging film and temperature on the rate and type of end-products caused by the growth of two main contras ting prevailing organisms in air and 100% CO2, Pseudomonas sp. and Lactobac illus sp., respectively. Methods and Results: Pseudomonas sp. and Lactobacillus sp. were inoculated individually on sterile meat fillets. The samples were packed in air or 100 % CO2, using a high and a low permeable film, and stored at 0 and 10 degree sC. Pseudomonas sp. grew aerobically and in 100% CO2 using high permeable f ilm at both storage temperatures, while film permeability significantly aff ected the growth Of Lactobacillus sp. Only at 10 degreesC. Enzymatic kits a nd HPLC and GC analysis were used to determine the chemical changes of the samples throughout storage. Pseudomonas sp. presented a greater rate of con sumption of glucose and lactate than Lactobacillus sp. in samples stored ae robically or with high permeable film. Propanol-1 and two unidentified orga nic acids were present only in samples inoculated with Pseudomonas sp., whi le acetaldehyde, ethanol, diacetyl and acetoin were detected in samples ino culated with Lactobacillus sp. Conclusions: Since different microbial species and introduction of new pack aging methods affect spoilage reactions of meat either qualitatively or qua ntitatively, a combination of several chemical indicators should be thoroug hly investigated. Significance and Impact of the Study: The present study p rovides information on how and when such potential indicators can be exploi ted for the benefit of the industry and consumer.