This study evaluated the microbial quality of ground beef and ground beef patties sold at local (Virginia) and Internet (U.S.) retail markets. A total of 152 ground beef products, consisting of locally purchased raw ground beef (LRG) and frozen beef patties (LFP) and Internet-procured frozen ground beef (IFG) and frozen beef patties (IFP), were tested. Results showed that LFP had significantly lower levels of aerobic mesophiles, psychrotrophs, and coliforms than LRG, IFG, and IFP. Furthermore, IFG had greater numbers of Escherichia coli than LRG and LFP. No sample was contaminated with E. coli O157: H7, but one duplicate set of summer LFP samples contained Salmonella. Listeria spp. were present in 25 and 29% of samples from local and Internet markets, respectively. About 5.0, 11.1, 10.5, and 7.9% of LRG, LFP, IFG, and IFP samples were contaminated with L. monocytogenes. This study identified differences in microbial quality between local and Internet products. Careful handling and thorough cooking of ground beef products, regardless of market source, are recommended to prevent foodborne illness.
The effects of formulation and freezing rate on the microstructure and quality of ground beef patties
