Research indicates tenderness begins with the seedstock producer's genetic decisions.
Since 1995 when the Beef Quality Audit revealed that one in four steaks "doesn't eat right," there has been a fast-paced quest to find ways to improve beef's tenderness.
Aging, high-voltage electrical stimulation (ES), and calcium-activated tenderization (CAT) have all been suggested as postmortem processes to improve tenderness. But that may be putting the cart before the horse.
When it comes to lessening the odds of having an undesirable eating experience, Colorado State University (CSU) meat scientist Gary Smith points his finger to the seedstock producer. "It's a matter of selection," says Smith.
Smith uses a quote from Bob Reed of Llano Estacado Winery to illustrate his point, "Once the grapes hit the dock, it's too late for us to correct the fruit. You can make good or bad wine from good grapes, but you can't make good wine from bad grapes."
The same is true with beef, Smith says. "It's difficult to produce tender beef using cattle that are inherently tough."
What Are The Probabilities? The chances of getting tough beef are high. As part of a study commissioned by the National Cattlemen's Beef Association (NCBA), a retail steak audit was conducted in eight U.S. cities to determine baseline probabilities for the expected rate of non-conformance (toughness).
Smith, along with CSU animal scientist Daryl Tatum and graduate student Matthew George, conducted the study.
The audit revealed that beef cuts were available to consumers in as few as three days or up to 45 days post-harvest, with 21 days being the average length of time between harvest and retail display. A "worst-case" baseline was established at three days, finding that one of two top sirloin steaks and nearly two of three top loin steaks had shear force values equal to or greater than 4.54 kg, indicating toughness. After 21 days of aging (considered the "normal" baseline) the expected toughness rate was still nearly one of three steaks.
As part of the NCBA study, genetic and postmortem interventions were examined in hopes of identifying a total quality management system that could be used to reduce the incidence of retail beef tenderness problems.
One hundred ninety-two steers, sired by 31 bulls (four to seven steer calves per sire), were evaluated for carcass tenderness. Eight sire breeds were represented: Angus, Belgian Blue, Braford (51/48 Hereford x 31/48 Brahman), Braunvieh, Charolais, Limousin, Red Brangus, (51/48 Red Angus x 31/48 Brahman) and Simmental.
The cattle were started on feed as calves and fed high concentrate grain diets in commercial feedlots until they attained approximately .45-in. external fat thickness at the 12th rib. Implants were administered twice (Synovex-S, followed by Revalor-S) during finishing.
All carcasses in the study were classified as A-maturity, and 92% of the carcasses had marbling scores of Slight and Small. The distribution of quality grades was 1% Prime, 6% upper 21/43 of Choice, 41% low Choice, 51% Select and 1% Standard.
Even after the combined use of aging, ES and CAT, nearly one of five steaks was classified as tough under the shear force specifications. This suggests postmortem technology cannot be expected to completely eliminate tenderness problems and that some attention must be given to improving the quality of "raw" materials, according to Smith.
Therefore, a second portion of the study evaluated the role of genetic intervention on improving tenderness. Two methods were evaluated:
* Genetic Intervention A - The worst 25% of sires were eliminated, based on progeny group means for top loin shear force values at day 14. Progeny of eight sires (four Bos taurus and four Bos indicus) were eliminated.
* Genetic Intervention B - The best 25% of sires were selected, based on progeny group means for top loin shear force values at day 14. Progeny of eight sires (five Bos taurus and three Bos indicus) were included in the selected group.
Elimination of the "worst" 25% of sires decreased the probability of non-conformance (toughness) to 0.18 for top sirloin steaks and 0.16 for top loin steaks. On the other hand, selection of the "best" 25% of sires reduced the probability of non-conformance to 0.11 for top sirloin steaks and .06 for top loin steaks.
But it was the combination of genetic and postmortem intervention that produced the most tender results. Selecting the best 25% of sires and using high-voltage ES, along with 14-21 days of aging, further reduced the expected rates of toughness to approximately 6% (1 of 17) for top sirloin steaks and 1% (1 of 100) for top loin steaks.
These results certainly suggest beef tenderness can be improved, but it needs to be through a total quality management approach which starts with genetic selection, followed by postmortem intervention, says Smith.