Shelf-Life Characteristics and Aerobic Plate Counts of Ground Beef As Influenced by Fat Level and Fat Source

Shelflife characteristics were scored in ground beef manufactured to certain levels of fat (16 ± 1%, 20 ± 1%, 24 ± 1%, 28 ± 1%) from various sources of fat trimmings (Choice flanks, plates, trimmings, brisket and kidney fat). Aerobic Plate Counts (APCs) were determined on the various lean and fat trimmings and the final ground beef (24 and 28% fat levels only). The characteristics were assessed over a 3-day retail display period. Off-odor was rated as stronger in ground beef formulated to 28% fat than to 16% fat. Increases in the duration of retail display were associated with greater darkening and surface discoloration of ground beef. Formulations with kidney and brisket fat had high (10⁷/g) APCs at the start of the shelflife study in one batch. However, the increase in APCs over the 3-day display was less for ground beef containing these two materials than for ground beef with fat from other sources. It would appear that APCs can be as high as 10⁷/g in 4- to 5-day postmortem trimmings under industrial conditions. Surface discoloration was strongly related with APCs (r = 0.82). The presence of 50-75% surface discoloration in ground beef was a good indication of APCs in excess of 10⁸/g.