Live Animal, Carcass and End Point
Beef Tenderness: Determination, Regulation and Prediction
Abstract:
The eating satisfaction from meat is the result of the interaction between tenderness, juiciness and flavor. We have shown that, under the primary system of finishing cattle in the U.S., there is very little variation in juiciness and flavor and that much of variation in eating satisfaction of rib and loin is the result of the variation in tenderness. This is not to say that juiciness and flavor are not important, because they are; it simply indicates that the inherent variation in flavor and juiciness is minimal. Thus, to address the variation in eating satisfaction, industry needs to address the variation in beef tenderness.
To address the variation in meat tenderness, we must understand the basis for such variation and then use that information/knowledge to ensure beef tenderness. Though the biological basis that accounts for between muscle variation will be detailed during the oral presentation, the abstract information is limited to longissimus (rib and loin) tenderness.
Until recently, Warner-Bratzler Shear Force (WBSF) was the most common method of measuring beef tenderness. Due to the need for higher throughput, we developed Slice Shear Force (SSF), which is becoming the method of choice for many, especially those who measure beef tenderness routinely.
Beef tenderness is influenced by a number of factors, including genetic, preharvest nongenetic factors and postharvest factors. With respect to the effect of genetics, work from the USMARC beef germplasm evaluation project has shown that
- 1) tenderness decreases linearly as Bos indicus inheritance increases;
- 2) there is little difference in tenderness among Bos taurus breeds;
- 3) there is a high degree of variation in tenderness within all breeds;
- 4) tenderness is weakly correlated to marbling score; and
- 5) tenderness is improved by the Piedmontese myostatin mutation.
The decreased tenderness of Bos indicus is due to decreased calpain-mediated postmortem proteolysis, due to increased activity of calpastatin. Genomic research to identify the mutations responsible for the decreased tenderness of Bos indicus lead to the development of commercial tests for SNP in µ-calpain and calpastatin, which are predictive of tenderness variation in random samples of carcasses of unknown origin sampled in commercial beef packing plants.
While genetic variation plays a significant role in controlling beef tenderness, in many experiments a large proportion of the variation in tenderness is either attributable to nongenetic factors or is unexplainable. With respect to nongenetic factors, our work over the years as well as others has shown that
- 1) by far 14 days of postmortem storage greatly influences tenderness and much of the observed variation in beef tenderness at the consumer level, can probably be explained by inadequate postmortem storage particularly around the national holidays when feature pricing increases demand and strains supply;
- 2) feeding 70-90 may have a positive effect on tenderness;
- 3) proper electrical stimulation enhances beef tenderness; and
- 4) tenderness decreases as the degree of doneness is increased.
Consequently, there has long been interest in development of a method to predict the tenderness of a carcass. The USMARC tenderness classification system is effective for predicting the tenderness of aged beef by testing the tenderness of a longissimus steak. The SSF technique is used daily to verify tenderness claims and has been adapted for both pork and lamb longissimus and more than 20 beef muscles. The USMARC noninvasive tenderness prediction system, based on visible and near-infrared reflectance spectroscopy, is commercially available and has been tested in several countries.
The USMARC noninvasive tenderness prediction system allows for the noninvasive identification of beef carcasses with an increased likelihood to have tender steaks. Ideally, to improve tenderness of our national herd, beef tenderness information collected at the packing plant or retail levels will be shared with the seedstock industry and the seedstock industry will use this information plus any genomic-based information to improve beef tenderness. An economic incentive for improved meat tenderness is required to encourage these activities industry-wide.
The decision by leaders of the beef packing industry that food safety is not a competitive issue and that any information that improves beef safety should be shared freely, has had a dramatic effect in improving the safety of the U.S. beef. We propose that a similar approach should be considered for improving the tenderness of the U.S. fed-beef supply.
Editor’s Note: The above material is provided by and posted with permission of the Beef Improvement Federation. Please direct reprint requests to BIF via the “Contact BIF” page at www.beefimprovement.org.
