2013 Annual Report
1a.Objectives (from AD-416):
Determine the relationship between VBG2000 beef carcass grading camera color thresholds for dark-cutter beef and flavor profile of longissimus steaks, USDA-AMS dark-cutting discounts, and packing plant grid dark cutter discounts.
1b.Approach (from AD-416):
At a commercial beef processor, we will select 40 severe dark cutters, 40 moderate dark cutters, 40 mild dark cutters, 40 carcasses with borderline (muddy) lean color and 160 normal cohorts. These carcasses will be graded with the VBG2000 E+V grading camera. We will obtain the USDA and processing plant dark-cutting discounts for these carcasses. The strip loin (IMPS #180) will be obtained from the left side of each carcass, vacuum-packaged, transported (1°C) to USMARC and aged (1°C) until 14 d postmortem. Four 2.54-cm steaks will be removed from the anterior end of each strip loin. One each for slice shear force assessment and simulated retail display, and two for sensory evaluation.
Slice shear force was higher for shady and mild dark cutters than for moderate and severe dark cutters. Trained sensory panel ratings for tenderness indicated that steaks from severe dark cutters were most tender, steaks from moderate, mild and normal color carcasses were intermediate, and steaks from shady dark cutters were least tender. Juiciness ratings differed among each dark cutter class and were highest for severe, followed by moderate, then mild and were not different between shady and normal color. Steaks from severe and moderate dark cutter carcasses were more likely to be scored higher for flavor traits considered to be objectionable. This study shows dark cutter and normal lean color carcasses differ in strip loin steak tenderness, juiciness, and flavor attributes and the direction and/or magnitude of those differences varies greatly depending on the severity of dark cutting. Steaks from severe and moderate dark cutter carcasses are likely to have off-flavors. Steaks from dark cutter carcasses with intermediate pH (shady and mild dark cutters) are most likely to be tough, yet many of these carcasses are included in routine U.S. Select and U.S. Choice product lines.