ObjectivesThe objective of this study was to investigate the effects of extended wet ageing on the flavor characteristics, of grass and grain fed Australian beef lumborum thoracis.Materials and MethodsCube rolls (HAM #2244) were collected from grass and grain fed cattle (n = 30) at a commercial abattoir near Brisbane, Australia. Cube rolls were vacuum packaged and shipped under refrigeration (0–2°C) to Texas Tech University. Each cube roll was cut into 2.5-cm steaks and labeled according to position from posterior to anterior end. Steaks were vacuumed packaged, stored through the appropriate postmortem ageing period (35, 45, 55, or 65 d postmortem), and then frozen until further analysis. One steak from each cube roll was used for trained descriptive flavor analysis with 8 trained panelists comprised of mostly graduate students from Texas Tech University. Flavor attributes of cooked steaks were scored using 100-point anchored line scales (0 = none, 50 = moderate, and 100 = strong).Data were analyzed used PROC GLIMMIX of SAS with diet, postmortem ageing, and their interaction as fixed effects and panelist as a random effect. Final temperature was tested as a covariate for all the flavor attributes.ResultsAn interaction was detected only for the bitter flavor and overall juiciness (P ≤ 0.03). Beef flavor ID, fat-like, metallic, umami, and sweet were not influenced by diet or postmortem ageing (P > 0.05). Ageing influenced bloody serumy flavor (P > 0.05) with 45 d samples having greater flavor than 55 d samples, but not differing (P > 0.05) from any other ageing period. Diet and ageing influenced rancid flavor (P > 0.05), with grass fed samples having a stronger rancid flavor than grain fed samples. Samples aged 65 d had a stronger rancid flavor than 45 or 55-d samples, and 35-d samples had the lowest rancid flavor. Diet and ageing influenced grassy flavor (P > 0.05), again being stronger in grass than grain fed samples. Samples aged 35 d had a weaker (P > 0.05) grassy flavor than any other ageing period, which did not differ (P > 0.05). Diet and ageing had an effect on liver-like flavor (P < 0.05) with stronger flavors in grain than grass fed samples and liver-like flavor increasing with postmortem ageing time. Sour flavor was affected by diet only (P < 0.05) with grass fed samples having stronger sour flavor than grain fed samples. Ageing had an effect on overall tenderness (P < 0.05); samples aged 35 d were least tender, and samples aged 45 d were more tender than 55 d samples but did not differ from 65 d samples.ConclusionThe results suggest that beef flavor as measured by beef flavor ID and umami were not impacted by extended ageing; however, some off-flavors grew stronger as ageing time extended. Flavor attributes such as rancid, grassy, sour were stronger in grass than grain fed samples, but grain fed has a stronger liver-like flavor. Ageing influenced both overall tenderness and juiciness, but typically not in a linear fashion.
Physical Changes during Post-Mortem Ageing of High-Value Impala (Aepyceros Melampus) Steaks