Effects of extended aging on the flavor characteristics of grass and grain fed Australian beef Longissimus thoracis

The objective of this study was to investigate the effects of extended aging on the flavor characteristics of Australian grass and grain fed beef longissimus thoracis (LT) To achieve this objective, Cube rolls (HAM #2244) of Australian grass and grain fed LT were collected, randomly assigned aging days (35, 45, 55, and 65) on day 1 postmortem, vacuum packaged and shipped under refrigeration (0-2ºC) to Texas Tech University (Lubbock, TX). Aged LT were further fabricated on each aging day, cut into steaks and labelled for different analyses. The steaks were then vacuum packaged and frozen (-24°C) until further analysis. Proximate composition, pH, objective color, Warner-Bratzler Shear Force (WBSF), trained panel, and cooked flavor volatile analyses were all determined. For proximate analysis, diet influenced both fat percentage and pH (P < 0.05) and an interaction between diet and aging was detected (P < 0.01) for moisture. For objective color, an interaction between diet and aging was observed for the lightness (L*) value (P < 0.05), while the redness (a*) and yellowness (b*) values were impacted only by aging (P < 0.05). No effect of diet, aging or their interaction was observed for WBSF (P > 0.05). According to trained panelist, an interaction was observed for the bitter flavor and juiciness between diet and aging (P < 0.05). Beef flavor ID, fat-like, metallic, umami, and sweet flavors were not influenced by diet or aging (P > 0.05). Diet and aging influenced rancid, grassy, and liver-like flavor (P < 0.05) with grass fed and 65 days aging having a greater rancid flavor, aging influenced bloody serumy and tenderness (P < 0.05) and sour flavor was influenced by diet (P <0.05). Aging influenced all flavor compounds except Acetaldehyde and methyl pyrazine (P < 0.05), an interaction effect was observed for 2, 3 –butanedione and 3-hydroxy-2-butanone (P < 0.05). Diet however did not have any effect on any of the cooked volatile compounds analyzed. Results indicate that extended aging had no impact on beef flavor ID and umami, but it led to stronger generation of certain off-flavors like rancid, grassy and liver-like.