THE EFFECT OF AGING METHODS ON POSTMORTEM BIOCHEMISTRY AND MEAT QUALITY

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: HATCH
• Reporting Frequency: Annual
• Accession No.: 0205374
• Project Start Date: Oct 1, 2005
• Project End Date: Sep 30, 2008
• Program Code: [(N/A)]- (N/A)

Recipient Organization
UNIVERSITY OF CALIFORNIA, DAVIS
410 MRAK HALL
DAVIS,CA 95616-8671

Performing Department
ANIMAL SCIENCE

Non Technical Summary
As the U.S. Hispanic population is exploding and projected to become the dominant group in the United States, particularly in California, before the century hits its half-way mark, the beef industry can't afford to lose this important ethnic market. The Hispanics and other ethnic consumers simply don't care for pre-packaged or pre-cut meat, which is the current method of merchandising meat at the supermarkets for many consumers, primarily Anglo consumers who do not like to cook. They prefer custom cutting, weighing, and wrapping of meat at the supermarkets. In order to appeal to this growing beef-consuming market, the effects of carcass-aging vs. pre-cut boxed-meat aging on postmortem biochemical changes and meat quality/palatability will be studied to recommend the best possible option of meat aging and merchandising practices.

Animal Health Component

65%

Research Effort Categories

Basic

35%

Applied

65%

Developmental

(N/A)

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
503	3320	1000	75%
503	3320	1030	25%

Knowledge Area
503 - Quality Maintenance in Storing and Marketing Food Products;

Subject Of Investigation
3320 - Meat, beef cattle;

Field Of Science
1030 - Cellular biology; 1000 - Biochemistry and biophysics;

Keywords

beef, aging, pre-cut, carcass, hispanic, ethnic, tenderness,

palatability

Goals / Objectives
In recent years the method of merchandising meat after slaughtering of meat animals has revolutionized with the introduction of boxed meat. Most carcasses are reduced to primal or subprimal cuts by the slaughterer within 48 hours after slaughtering, vacuum packaged and placed in boxes for shipment. The National Meat case Study 2004 by the Cattlemen's Beef Board presents compelling evidence that the butcher block of yore is indeed ceding to pre-cooked and pre-packaged products, and in formats as varied as boxed-and branded and case-ready. The driver, of course, is the consumer. This method of merchandising meat is appealing to many consumers (primarily Anglos) who do not like to cook and who shop pre-cut, pre-packaged or precooked products. On the other hand, a growing segment of population, particularly in California, is Hispanics and other ethnic groups. The Hispanic and other ethnic consumers simply don't care for pre-packaged or pre-cut meat. A full-time butcher is employed by the supermarket to cut, weigh and wrap products (it is called old-fashioned meat merchandising). It is likewise worth noting that the U.S. Hispanic population is exploding, and projected to become the dominant group in the United States before the century hits its half-way mark. True, there is the issue of acculturation, meaning that second- and third-generation Hispanics or ethnic groups will likely be less inclined to visit the butcher than their parents and grandparents. But for the moment, and the foreseeable future, they represent a growing cultural force that the meat industry, particularly the beef industry, can't afford to lose. In addition, the Hispanics consider meat a status symbol important to the traditional Hispanic diet and they spend 37 percent more per person per year on meat than Anglos and, beef is their preferred meat. In order to appeal to this growing beef-consuming market, we have to examine and compare two merchandising practices (old-fashioned carcass/side/quarter merchandising vs. pre-cut/pre-packaged merchandising) on post-mortem muscle biochemistry and meat quality. Surprising, there are very little data that compare carcass-aging vs. boxed-meat aging on their effects on postmortem muscle changes and meat palatability. The objectives of this project are three-folds: 1.To study the effects of carcass-aging vs. pre-cut boxed-meat aging on postmortem biochemical changes including breakdown of muscle proteins, shortening of myofibrils, and other properties of fresh meat. 2.To evaluate the effects of the above two aging methods on meat palatability and relate the results to the biochemical changes observed in Objective 1. 3.To recommend the best possible option of meat aging and merchandising method to enhance the meat palatability for the growing population of Hispanics and other ethnic groups.

Project Methods
A. Experimental materials: Sixteen Beef cattle of known genetic make-up that reached an average market of 1200 pounds will be transported from the UC-Davis feedlot and slaughtered at the Cole C facility by the standard procedures. After the carcasses are chilled for 48 hours, one side of each carcass will be hung in the 2 degrees celeus cooler for up to 14 days (CA: carcass aging group); whereas the other side will be fabricated to subprimal cuts, vacuum packaged, and stored in a 4 degrees celeus cooler (PA: pre-cut aging group). Four muscles (longissimus, semimembranosus, triceps brachii, biceps femoris)from each aging treatments will be analyzed at 2, 4, 8, and 14 days of aging. B. Tenderness measurement: Duplicate 1-inch steaks from four muscles will be broiled to an internal temperature of 70 degrees celeus, and determined for the tenderness by the Warner-Bratzler shear press method and the subjective scoring of six-member taste panel. C. Biochemical Analyses: Muscle samples will be taken for the analyses of MFI (Myofibril Fragmentation Index), pH, postmortem degradation of myofibrillar proteins by electrophoresis, and sarcomere length. D. Histochemical Analyses: Postmortem changes in muscle structure will be evaluated by light and transmission electron microscopy at different aging periods. E. Statistical analyses and correlation: An ANOVA will be conducted using the GLM procedures of SAS and correlation between the meat tenderness and biochemical variables will be examined to explain the observed differences, if any, between the aging treatments. F. The experiments will be repeated with several sets of experimental materials as needed and as revised, and final recommendation will be made on the best possible method of beef aging acceptable to the growing population of the Hispanics and other ethnic groups.

Progress 10/01/05 to 09/30/08

Outputs
OUTPUTS: The recent innovation in meat merchandising has changed the ways of aging carcass and meat. In the past the industry used "dry-aging" in which carcasses were hung in a cooler for 7-21 days, after which there were fabricated into retail cuts and sold to consumers. Recent introduction of boxed meat employs "wet-aging" in which carcasses are fabricated into subprimal cuts in 2 days after slaughter, vacuum packaged and aged in the box during transportation and storage until they are sold to customers in the retail stores. The growing population of Hispanic and other racial ethnic customers in California prefer "dry-aged" meat, whereas the general public is consuming "wet-aged" meat. Surprisingly, there is little definitive scientific study if aging methods affect meat quality significantly. Meat tenderness of loin, top round, and cross-rib roast was determined at 2, 4, 8, and 14 days of aging. Dry-aged (DA) loin muscles were more tender (P less than .05) at 4 and 8 days of aging with shear values of 6.5 and 5.2 kg, respectively as compared to wet-aged (WA) loin muscles with shear values of 7.1 and 5.8 kg, respectively. No significant differences were found at 2 or 14 days of aging. The final shear values at 14 days of aging were 5.2 and 5.6 kg for DA and WA loin muscles, respectively. The differences in tenderness at 4 and 8 days of aging were attributed to the greater tension and stretching imposed on the muscle by carcass hanging in DA method, as evidenced by longer sarcomere length of 1.85 Mu at 8 days of aging for the DA loin as compared to 1.75 Mu for the WA loin. No differences were found in the myofibrillar fragmentation index between the aging methods throughout the aging periods, indicating that postmortem degradation of muscle proteins was not affected by the aging methods. Similar effects of aging methods were also observed for top round muscles. DA significantly (P less than .05) improved meat tenderness at 2, 4, and 8 days of aging with small differences at 14 days for top round muscles. However, no differences were found in cross-rib roasts. Based on the results of two trials, it is concluded that dry-aging method would enhance meat tenderness of muscles in the hindquarter to a greater extent than wet-aging when they are sold before being fully aged, that is, less than 14 days after slaughter. If beef is fully aged for 14 days as commonly practiced with merchandising of boxed meat in large supermarkets, however, aging method does not affect meat tenderness and overall palatability. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: The results of this study is of great benefit for the small scale meat stores that are catering to racial ethnic people, particularly for the growing population of Hispanic people. It will also benefit California cattle growers and packing industry. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
Two different aging methods of either dry-aging or wet-aging can affect the tenderness of some muscles, particularly those muscles in the hind quarter. For racial ethnic markets including meat stores for the Hispanic people where beef is sold before being fully aged (typically less then 14 days after slaughter), dry-aging method would be a better choice of aging for more tender beef. On the other hand, aging method will not affect the final tenderness of beef in the large supermarkets for the general public where fully-aged (longer than 14 days) boxed meat is merchandised. Because the racial ethnic population, particularly the Hispanic population who loves beef, is continuously increasing in California, it would be beneficial to use dry-aging method for this segment of population to increase beef consumption and greater profit for California beef producers.

Publications

• Lee, Y.B. 2008. Aging methods of beef on postmortem biochemistry and meat quality. Journal of Animal Science (in press).

Progress 01/01/07 to 12/31/07

Outputs
OUTPUTS: Another trial with eighteen market weight cattle of 586 kg (Herford x Angus) were conducted to further determine the effects of aging methods on postmortem biochemistry and meat quality. The animals were slaughtered according to the standard procedures, chilled for 48 hours at 1C, and graded according to the standards of USDA beef grading. One side of each carcass was fabricated to subprimal cuts, vacuum packaged and stored at 2C cooler (BAT: Boxed-beef Aging Treatment), whereas the other side was hung in the same cooler of 2C as an intact carcass (CAT: Carcass Aging Treatment). Three muscles of loin (longissimus dorsi), top round (semimembranosus), and cross-rib roast (triceps brachii) were pulled out from each treatment group at 2, 4, 8, and 14 days of aging. Loin muscles from CAT were more tender (P<.05) at 4 and 8 days of aging with shear values of 6.5 kg and 5.2 kg, respectively as compared to those from BAT with shear values of 7.1 g and 5.8 kg, respectively. There were no significant differences at 2 or 14 days of aging. The final shear values at 14 days of aging were 5.2 kg and 5.5 kg for CAT and BAT, respectively. The differences in the tenderness at 4 and 8 days of aging in the loin muscle could be attributed to the greater tension and stretching imposed to the muscle by hanging as evidenced by longer sarcomere length of 1.85 μm at 8 days of aging for the CAT as compared to 1.72 μm for the BAT. No differences were found in the myofibrillar fragmentation index between the treatments throughout the aging periods, indicating that postmortem degradation of muscle proteins was not affected by the aging methods. The effects of treatment on meat tenderness were also observed in top round muscle. CAT significantly (P<.05) improved meat tenderness of top round muscle at 2, 4, and 8 days of aging with little difference at 14 days. Again, the differences in the tenderness between two treatments were attributed to the differences in sarcomere length resulted from a greater tension and stretching for the CAT. No difference was found in meat tenderness as well as in sarcomere length between treatments for the cross-rib roast muscle. It was evident that different muscles were affected to a different extent, depending on their locations in the carcass. Loin and top round muscles that were stretched to a greater extent by CAT aging method were significantly more tender until 8 days of aging, after which time no differences were observed. Based on the results, it is recommended that if meat is sold before 8 days in the cooler as practiced by small stores for racial ethnic people, it is better to employ carcass aging method for more tender beef. If meat is aged longer than 8 days, however, as commonly practiced with merchandising of boxed beef in large supermarket chain stores, aging method does not affect meat tenderness and overall meat palatability. PARTICIPANTS: undergraduate students working as interns in the University slaughter facility and meat lab. Training of students who are interested in meat research TARGET AUDIENCES: To promote the consumption of beef to Hispanic people and other racial ethnic people PROJECT MODIFICATIONS: no modification

Impacts
Two different aging methods of either carcass-hanging or boxed beef can affect the tenderness of some muscles, depending on their locations in the carcass. For racial ethnic markets including meat stores for the Hispanic people where beef is sold before its full aging (typically less than 14days after slaughter), carcass-hanging method would be a better choice of aging for more tender beef. On the other hand, aging method will not affect the final tenderness of beef for the large supermarkets for the general public where fully-aged (longer than 14 days) boxed beef is merchandised. The study supports the idea that carcass hanging method should be recommended to small meat stores for racial ethnic people.

Publications

• Lee, Y.B. 2008. Aging methods of beef carcass on postmortem biochemistry and meet quality. Journal of Animal Science. (in press)

Progress 01/01/06 to 12/31/06

Outputs
Sixteen market weight cattle of 560 kg (Hereford x Angus) were slaughtered according to the standard procedures. After chilling for 48 hours at 1C, one side of each carcass was fabricated to subprimal cuts, vacuum packaged and stored in a 4 C cooler (PAT: Pre-cut Aging Treatment), whereas the other side was hung in the same cooler as an intact carcass (CAT: Carcass Aging Treatment). Four muscles of loin (longissimus dorsi), top round (semimembranosus), bottom round (biceps femoris), cross-rib roast (triceps brachii) were pulled out from each treatment group at 2, 4, 8, and 14 days of aging. Loin muscles from CAT was more tender (P<.05) at 2, and 4 days of aging with shears values of 7.5 kg and 6.5 kg, respectively as compared to those from PAT with shear values of 8.3 kg and 7.0 kg, respectively. Though the differences between two treatment groups existed throughout the remaining aging periods of 8 and 14 days, they were not significant. The final shear values at 14 days of aging were 5.4 kg and 5.7 kg for CAT and PAT, respectively. The differences in the tenderness at 2 and 4 days of aging in the loin muscle could be attributed to the greater tension and stretching imposed to the muscle by hanging as manifested by a slightly longer sarcomere length of 1.90 μm at 4 days of aging for the CAT as compared to 1.82 μm of the PAT. No differences were found in the electrophoretic pattern of myofibrillar proteins between the treatments at all aging periods, indicating that postmortem degradation of muscle proteins was not affected by the aging methods. The effects of treatment were greater for the top and bottom round muscles. The shear values of the top round muscle of CAT were 8.7, 8.0, 7.2, and 6.0 kg at 2, 4, 8, and 14 days postmortem, respectively as compared to 9.9, 9.0, 7.7, and 6.5 kg of PAT. A significant difference in sarcomere lengths was also found between the treatments at 2 days of aging, 2.12 μm for CAT 1.92 μm for PAT. Again, the differences in the shear values between the treatments were attributed to the differences in sarcomere lengths resulted from a greater tension and stretching for the CAT. Similar effects were also observed for the bottom round muscles. However, no differences was found for the cross-cut roast muscle, indicating that the aging methods did not affect neither sarcomere length nor postmortem breakdown of myofibrillar proteins. It was concluded that different muscles were affected differently, depending on their locations in the carcass. Loin, bottom round and top round muscles that were stretched to a greater extent by CAT aging method were significantly tender until 4 days of aging, followed by insignificant differences after 4 days postmortem. Therefore, it is recommended that if the meat is sold before 7 days of aging as practiced by small stores for racial ethnic people, it is better to employ carcass aging method for a more tender beef. If meat is aged longer than 7 days as commonly practiced with merchandising of boxed meat in most of large supermarket chains, aging method does not make much differences in meat palatability.

Impacts
Two different aging methods of either carcass-hanging or pre-cut boxed meat can affect the tenderness of meat for different merchandising routes. For the racial ethnic markets including meat stores for the Hispanic people where meat is sold before its full aging (less than 14 days after slaughter), carcass-hanging method will be a better choice of aging for more tender beef. On the other hand, for the large conventional supermarkets for the general public where fully-aged boxed meat is merchandised, aging method will not affect the final tenderness of meat. In addition, because boxed-meat merchandising is more cost-effective, this practice will continue for the large scale supermarkets.

Publications

• No publications reported this period