According to a new study performed by researchers from the University of Naples Federico II, Naples, Italy, a modified atmosphere of 60% oxygen and 40% carbon dioxide had the best protective effect on beef after storage at 5°C for 14 days. The researchers also tested modified-atmosphere packaging (MAP) conditions of 20% oxygen 40% carbon dioxide, as well as ambient air. The results of the study were published in the July 2006 issue of Applied and Environmental Microbiology (see http://aem.asm.org/).
At set intervals during the course of the study, the researchers determined levels of Pseudomonas, Enterobacteriaceae, Brochothrix thermosphacta and lactic-acid bacteria present in the beef samples. They also analyzed the beef to determine headspace gas composition, weight loss and any color changes to the beef. Results showed that the atmosphere of 60% oxygen and 40% carbon dioxide had the best protective effect, keeping the microbial loads and color change to acceptable levels in the first 7 days of refrigerated storage. The researchers also noted that different microbial species existed on different samples depending on the type of MAP employed.
The goal of the study was to identify spoilage-related microbiota by molecular methods to help establish effective storage conditions for fresh meat. According to the researchers, this is the first study to report the changes of spoilage-related microbial flora during storage of fresh meat.
Beef is one of the most-perishable meats. According to the National Cattlemen's Beef Association, Centennial, CO, retailers lose nearly $1 billion annually in fresh-beef sales under typical packaging conditions due to shortened shelf life.
