Beef Longissimus Slice Shear Force Measurement Among Steak Locations and Institutions

Authors: Wheeler, Tommy; Shackelford, Steven; Koohmaraie, Mohammad

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/14/2007
Publication Date: 9/20/2007
Citation: Wheeler, T.L., Shackelford, S.D., Koohmaraie, M. 2007. Beef longissimus slice shear force measurement among steak locations and institutions. Journal of Animal Science 85:2283-2289.

Interpretive Summary: Slice Shear Force is an instrumental measure of tenderness that was originally developed at USMARC as a rapid tenderness sorting process for beef carcasses. However, slice shear force has many advantages over Warner-Bratzler shear force which is the historically used instrumental measure of tenderness. Slice shear force can be conducted much easier and faster and is a more repeatable measurement than Warner-Bratzler shear force. For these reasons, the National Cattlemen’s Beef Association recommended that slice shear force be used as the standard method of tenderness measurement. Thus, numerous institutions have adopted or are considering adopting slice shear force for routine ribeye steak tenderness measurement. The present experiments were conducted to determine whether other institutions could accurately and repeatably measure slice shear force on beef ribeye steaks after receiving expert training on the procedure and a standard kit of equipment. Seven institutions measured slice shear force on a set of duplicate steaks. Four institutions had highly accurate and repeatable slice shear force measurements. One institution was accurate but lower in repeatability and another was lower in accuracy but high in repeatability. One institution was lower in accuracy and repeatability. The results indicate the importance of cooking in the measurement of tenderness and emphasize that with proper training and application of the protocol, slice shear force is a highly repeatable measure of beef ribeye steak tenderness.

Technical Abstract: The objectives of this study were 1) to evaluate slice shear force on every longissimus thoracis et lumborum steak to determine which steaks were appropriate for slice shear force measurement and 2) to train six other institutions to conduct slice shear force and then determine the among and within institution variation in longissimus slice shear force values. In experiment one, longissimus thoracis et lumborum were obtained from the left sides of 50 U.S. Select carcasses. Thirteen longissimus thoracis and 12 longissimus lumborum steaks were cut 2.54-cm thick from each side. Slice shear force was measured on each steak. Mean slice shear force among steaks (1 to 25) ranged from 19.7 to 27.3 kg. Repeatability of slice shear force among steaks ranged from 0.71 to 0.96. In experiment two, the longissimus thoracis et lumborum were obtained from the left sides of 154 U.S. Select beef carcasses. Eight 2.54-cm thick steaks were obtained from the posterior end of each frozen longissimus thoracis and six 2.54-cm thick steaks were obtained from the anterior end of each frozen longissimus lumborum. Steaks were assigned for measurement of slice shear force to seven pairs of consecutive steaks. Institutions were assigned to steak pairs within each carcass using a randomized complete block design such that each institution was assigned to each steak pair 22 times. Repeatability estimates for slice shear force for the seven institutions were 0.89, 0.83, 0.91, 0.90, 0.89, 0.76, and 0.89, respectively, for institutions 1 to 7. Mean slice shear force values were lowest (P < 0.05) for institutions 3 (22.7 kg) and 7 (22.3 kg), and were highest (P < 0.05) for institutions 5 (27.3 kg) and 6 (27.6 kg). Institutions with higher mean slice shear force (institutions 5 and 6) used cooking methods that required more (P < 0.05) time (32.0 and 36.9 min vs 5.5 to 11.8 min) to reach the endpoint temperature (71ºC) and resulted in higher (P < 0.05) cooking loss (both 26.6% vs 14.4 to 24.1%). Differences among institutions in the repeatability of slice shear force were partially attributable to differences among institutions in the consistency of steak thawing and cooking procedures. These results emphasize the importance of sample location within the muscle and cooking in the measurement of tenderness and indicate that with proper training and application of the protocol, slice shear force is a highly repeatable measure of beef longissimus tenderness.