The objective of this study was to evaluate the effects of extended wet-aging on the beef flavor profile of grass and grain-fed Australian strip loins.

Strip loins (HAM 2140) were collected from grass and grain finished cattle (n = 50) at a commercial abattoir near Brisbane, Australia. Subprimals were portioned into sections and assigned randomly to 1 of 3 postmortem aging periods (45, 70, or 135 d). Portions were individually vacuum packaged and shipped refrigerated (0–4°C) to Texas Tech University in Lubbock, TX. Upon arrival, the strip loin sections were sorted into respective aging groups of 45D, 70D, and 135D and stored at 1–2°C. On each respective day, sections were fabricated into 2.54-cm steaks, vacuum packaged and frozen (–21°C). Electric clamshell grills were used to cook thawed (held at 2–4°C for 24 h) steaks to a medium degree of doneness (71°C); cooked temperatures were recorded. Steaks were cut into cubes and evaluated by trained panelists (n = 6) for descriptive sensory attributes using a 100-mm anchored line scales (0 = slight, 50 = moderate and 100 = strong).

The sour flavor was the only trait where an interaction between diet and postmortem aging was detected (P < 0.01). Samples aged 135 d from both grass and grain were similarly (P > 0.05) scored with a stronger (P < 0.05) sour flavor than all other treatment combinations, which did not differ (P > 0.05). Aging impacted (P ≤ 0.01) beef flavor ID, liver-like, metallic, rancid, green-hay, umami, and bitter flavors, as well as overall juiciness and overall tenderness. For beef flavor ID, 45D aging resulted in the greatest intensity (P < 0.05), while 70D samples were intermediate, and 135D samples were the least intense. For liver-like, metallic, rancid, green-hay, and bitter flavors, 135D samples had the strongest flavor, while 70D samples were intermediate, and 45D samples had the weakest flavor intensity (P < 0.05). For umami, 45D samples had stronger (P < 0.05) umami flavor than 135D samples, but 70D samples did not differ from either 45D or 135D (P > 0.05). Panelists rated 70D and 135D samples juicier (P < 0.01) than 45D samples, but 70D and 135D did not differ (P > 0.05). For overall tenderness, panelists rated 135D samples more tender (P < 0.05) than 45D and 70D, which were similar (P > 0.05). Diet impacted (P < 0.05) bloody/serumy, liver-like, green-hay, and bitter flavors. For bloody/serumy and liver-like, the grain fed treatments resulted in greater (P < 0.05) flavor intensity than grass fed treatments. However, grass fed samples had stronger (P < 0.05) green-hay and bitter flavors compared to grain fed samples. Diet and aging had no effect (P > 0.05) on fat-like or sweet flavors.

Extending postmortem aging of Australian beef strip loins from 45 to 135 d resulted in decreased beef and umami flavors, along with concurrent increased detection of off-flavors, such as liver-like, rancid, and sour. Diet influenced fewer flavor traits than postmortem aging, but grass-fed samples still had stronger green-hay flavor, as would be expected. Based on these results, aging beef strip loins 135 d is not recommended based on reduced beef flavor and increased off-flavor detection.