Document Type

Thesis - University Access Only

Award Date

2010

Degree Name

Master of Science (MS)

Department / School

Animal Science

Abstract

One objective of this study was to gain a more complete understanding of the intrinsic factors that regulate tenderness by determining if a relationship between sarcomere length and postmortem proteolysis exist. An understanding of these factors was important in the second objective which was to evaluate a novel optical imaging method to predict tenderness. Two-dimensional optical reflectance in beef muscles was acquired by a point incident light. Five parameters were extracted from each reflectance image to quantify the reflectance profiles from 336 beef samples obtained (14 steers x 2 sides x 3 muscles x 4 aging periods). Parameters were evaluated on samples collected from 7 Bos indicus and 7 Bos taurus steers. Genetic differences were utilized to maximize variation in postmortem proteolysis. To alter sarcomere length, one side of each carcass was suspended from the Achilles' tendon (NS) while the other was hip suspended (HS). Three muscles were sampled from each side to provide variation in connective tissue characteristics: longissimus dorsi (LO), semitendinosus (ST), and psoas major (PM). The effects of animal breed, muscle, suspension method, and aging were investigated. Sarcomere length appeared to have little relationship to postmortem degradation of desmin or troponin-T (TnT). However, when samples were pooled by suspension method, it was apparent in the LD that greater degradation of TnT had occurred in samples with shorter sarcomeres (*** P < 0.001 ). With the exception of scattering intensity, all optical parameters were different (P < 0.05) among the three muscles. No parameters were correlated to degradation of TnT or desmin, but relationships between the parameters aging and were visible. In the PM, NS sides had higher (P < 0.001) q values than HS sides which had shorter sarcomeres. The LD from NS sides revealed significantly lower (P < 0.01) B values than those from HS sides. Scattering intensity was greater (P < 0.05) in the LO and ST of Bos indicus compared with Bos taurus carcasses. The q parameter was higher (P < 0.05) in the LD and ST from Bos indicus carcasses compared to Bos taurus, but the reverse (P < 0.05) was noted for the PM. Also, Bos taurus samples had higher (P < 0.05) values than Bos indicus carcasses for both spatial gradients. Also, results indicated that scattering intensity measured at 1 d was correlated (R 2 = 0.50) with 10 d Warner-Bratzler shear force (WBSF) in the LD; and the q parameter measured at 1 d was correlated (R2 = 0.53) with 10-d WBSF in the M. psoas major. These results suggest that reflectance images may provide valuable information for beef tenderness prediction.

Library of Congress Subject Headings

Beef -- Quality

Muscles

Reflectance

Format

application/pdf

Number of Pages

85

Publisher

South Dakota State University

Download

Share

COinS