Different Packaging Conditions May Effect Spoilage of Refrigerated Beef
Researchers from Italy have found that different packaging methods utilizing air, oxygen and carbon dioxide can have an impact on the microbial spoilage of refrigerated beef. They report their findings in the July 2006 issue of the journal Applied and Environmental Microbiology.
Recognized as one of the most perishable foods, beef spoilage is commonly attributed to high water content and abundance of surface nutrients. Oxidation and color change are two obvious physical changes that occur when meat goes bad, however the growth of potentially harmful microorganisms has prompted researchers to examine new packaging methods to minimize microbial spoilage.
In the study beef was contained using three different methods of modified-atmosphere packaging (MAP) and stored at 5 degrees Celsius for fourteen days. The first method consisted of air (MAP1), the second of 60% oxygen and 40% carbon dioxide (MAP2), and the third of 20% oxygen and 40% carbon dioxide (MAP3). While stored, the beef was monitored for viable counts of Pseudomonas, Enterobacteriaceae, Brochothrix thermosphacta, and lactic acid bacteria as well as headspace gas composition, weight loss, and color change. During the first seven days, packaging method MAP2 was shown to offer the best protection, maintaining acceptable microbial loads and color change. Spoilage did occur between seven and fourteen days and although many different genera and species were identified some were found more frequently and appeared to vary according to packaging conditions. Rahnella aquatilis, Rahnella spp., Pseudomonas spp., and Carnobacterium divergens were prominent in the air packaging method, Pseudomonas spp. and Lactobacillus sakei were found in packaging high in oxygen content, and finally Rahnella spp. and L. sakei were the main species identified during storage high in carbon dioxide.