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ARS Home » Plains Area » Clay Center, Nebraska » U.S. Meat Animal Research Center » Meat Safety and Quality » Research » Publications at this Location » Publication #350610

Research Project: Strategies to Optimize Meat Quality and Composition of Red Meat Animals

Location: Meat Safety and Quality

Title: Characterizing the ham halo condition: A color defect in fresh pork biceps femoris muscle

item King, David - Andy
item Shackelford, Steven
item SCHNELL, TIM - Kraft Foods
item PIERCE, LEE - Kraft Foods
item Wheeler, Tommy

Submitted to: Meat and Muscle Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/19/2018
Publication Date: 7/5/2018
Publication URL:
Citation: King, D.A., Shackelford, S.D., Schnell, T., Pierce, L., Wheeler, T.L. 2018. Characterizing the ham halo condition: A color defect in fresh pork biceps femoris muscle. Meat and Muscle Biology. 2(1):205-213.

Interpretive Summary: Color of cured pork products is critical to meeting consumer expectations. A ham color defect was identified by industry as a band of very pale muscle tissue in ham muscles resulting in uneven cured color. The goal of this study was to identify the mechanism and potential solutions for this color problem. Results indicate that the pale portion of the muscle had much less myoglobin pigment (the protein that makes pork reddish/pink) compared to the normal colored portion of the muscle. This study identified genetic selection for increased muscle pigment as a potential solution to reduce, or eliminate, the pale ham muscle problem.

Technical Abstract: This experiment characterized a color defect called halo, involving pale tissue in the superficial portion of ham muscles, causing a two-toned appearance. Biceps femoris muscles (n = 200) were obtained from the ham-boning line of a large processor. instrumental color attributes were determined on the medial (inside) and lateral (halo) surfaces of the muscle. Muscles were sliced (2.54-cm-thick) perpendicular to the long axis of the muscle. Slices were numbered from the proximal end of the muscle so that slice numbers represented anatomical location. Severity of the defect was greatest on the distal end of the muscle corresponding to slices 6 and 7 (9 locations). The halo and inside portions of slices 6 and 7 were separated for myoglobin concentration and muscle pH determination. The inside portion of muscle had lower (P < 0.001) L* (53.1 versus 63.4) and greater (P< 0.001) a* (23.2 versus 15.3) and b* (18.5 versus 15.4) values than the halo portion. Compared to the halo portion, the inside portion of the muscle had greater (P < 0.001) muscle pH (5.7 versus 5.5) and myoglobin concentration (1.97 versus 0.85 mg/g). Four minimally and 5 severely affected muscles were sampled in the halo and inside portions for muscle fiber typing. Fiber type distribution did not differ (P > 0.05) between locations within minimally affected muscles. In severely affected muscles, the inside portion had increased (P < 0.001) proportion of type I fibers, and concomitant decrease (P < 0.001) in type IIB fibers relative to the halo portion. These data indicate that the halo portion of the muscle is much lighter and less red in color, resulting from reduced myoglobin concentration in this portion of the muscle associated with a shift in muscle fiber type. These results should contribute to solutions to mitigate the ham halo color defect.