Date of Award:

12-2008

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Nutrition, Dietetics, and Food Sciences

Department name when degree awarded

Nutrition and Food Sciences

Committee

Daren P. Cornforth

Abstract

Liver off-flavor is a sporadic problem that limits the consumer acceptance of several beef chuck muscles, including the infraspinatus (flat iron steak). Residual blood hemoglobin is known to contribute to liver off-flavor development. This study was conducted to evaluate factors affecting development of liver off-flavor after cooking of beef chuck (shoulder) muscles. The study was conducted in three parts.

The objective of part 1 was to determine effects of muscle (infraspinatus, longissimus dorsi, serratus ventralis, supraspinatus, teres major) and processing (with or w/o carcass electrical stimulation) on residual blood hemoglobin content and total pigment content of raw muscle and sensory characteristics after cooking to 71 or 82°C. The objective of part 2 was to evaluate the effect of antioxidant treatment and anaerobic packaging to possibly reduce the incidence of liver and other off-flavors of beef infraspinatus (IF) steaks. The objective of part 3 was to determine the effect of animal age (commercial grade; > 42 months, compared to select grade; < 30 > months), antioxidant treatment, and anaerobic packaging on sensory characteristics of beef IF steaks.

Among beef chuck muscles, the infraspinatus had highest mean liver flavor score of 2.08±1.00 where 2=slightly intense liver flavor. Other muscles (longissimus dorsi, serratus ventralis, supraspinatus, teres major) had mean liver flavor scores less than 2. Liver flavor score, myoglobin, hemoglobin, and total pigment content were higher (p < 0.05) for infraspinatus muscle from older animals. Among select grade muscles, carcass electrical stimulation had no significant effect on liver flavor score. Rancid flavor scores were significantly increased from 1.34±0.65 to 1.58±0.84 as internal cook temperature increased from 71 to 82°C but mean TBA values as a measure of rancidity (0.25±0.15 and 0.29±0.13, respectively) were not affected by cook temperature.

Antioxidant treatment significantly reduced TBA values, rancid, and liver flavor scores for aerobically packaged steaks (PVC or 80% O2-MAP) but had little effect on scores of steaks in anaerobic packaging (0.4% CO-MAP). Results of this study indicate that infraspinatus steaks from older animals are most likely to have objectionable liver, sour/grassy, or rancid flavors. Objectionable flavor scores were lower in steaks receiving antioxidant injection or packaged anaerobically in 0.4% CO-MAP.

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