Bacteria and Volatile Compounds Associated with Ground Beef Spoilage

Ground beef (GB) samples were maintained in atmospheres of 2 or 18% oxygen. Similar putrid spoilage occurred at both concentrations, although the microflora differed. Two of 10 isolates from fresh and spoiled GB, nonfluorescent pseudomonads, produced putrid aromas but only 4 volatile compounds in common when inoculated into sterile GB. A Moraxella isolate produced a pronounced estery, decayed vegetable odor while others produced a decayed straw, ammoniacal or sour aroma. Differences in spoilage aromas apparently were not characterized by individual compounds but rather by the concentration of sulfur compounds and their ratio to other compound classes. Acetone, methyl ethyl ketone, dimethyl sulfide and dimethyl disulfide were indexes of microbial spoilage.