| dc.description.abstract | The objective of this study was to gain a better understanding of the occurrence of persistent pinking by evaluating ground beef with different fat percentages packaged with carbon monoxide modified atmosphere packaging (CO-MAP). Three cases of fine ground beef (IMPS 136) with targeted lean/fat percentages of 73/27, 81/19, and 93/7 were collected from a commercial packing facility. Ground beef was stored for 10 d. After storage, each ground beef chub was opened and reground with a 3 mm stainless steel grinder plate together to form one composite batch of each fat percentage. After grinding, 225 g patties were weighed, formed utilizing a patty maker, and placed onto foam trays (n = 81) with an absorbent pad and overwrapped with polyvinylchloride film (PVC). The trays were randomized within each fat percentage and were then placed in master bags (n = 27) in groups of three with one oxygen scavenger per bag. Twenty-seven master bags were flushed with a tri-gas blend of 0.4% CO, 30% CO2, and balance N2. Master bags were then held in dark storage until pull day: 1 d, 8 d, or 15 d. On each pull day, 9 master bags were removed from dark storage, and the trays were placed in a display case for retail display evaluation for 3 d. Headspace analysis was conducted before each master bag was opened. Instrumental and objective color measurements were collected on d 0 – 2 of retail display. Visual color and surface discoloration were analyzed daily by a trained panel (n = 6). The formation of carboxymyoglobin (COMb) was confirmed by measuring ratio of absorbance at 543 nm/581 nm. Patties were cooked to an internal temperature of 71°C. Internal cooked color was evaluated by a trained panel (n = 6) along with instrumental color reading post cooking. The results of the study showed the 93/7 patties had higher a* values throughout retail display over all pull days. All patties had formed COMb by retail display, regardless of storage day or fat percentage. The 93/7 patties had consistently browner internal subjective cooked color scores compared to the 73/27 patties. The 73/27 patties from all pull days were significantly (P < 0.05) redder than the 93/7 patties, and on pull d 1 and 15, the 81/19 and 73/27 patties had significantly (P < 0.05) redder cooked a* values than the 93/7 patties. COMb was formed in CO-MAP regardless of ground beef fat percentages or pull day. Additionally, ground beef with more fat (73/27) had more pinking after cooking to recommended internal temperature compared to lower fat blends. With consumer confusion on pinking within meat products post cooking, further research should be conducted to better understand the relationship of fat content of ground beef and dark storage times resulting in persistent pinking. | |
