BEEF QUALITY-WHAT IS IT？ HOW TO PRODUCE IT.ppt

1、BEEF QUALITY: WHAT IS IT? HOW TO PRODUCE IT,Harlan Ritchie Department of Animal Science Michigan State University East Lansing, Michigan 48824,WHAT IS BEEF QUALITY?,In fresh, uncooked beef, it is: Color of the muscle Amount of fat Subcutaneous fat (external fat; on border of muscles) Intermuscular f

2、at (seam fat; between muscles) Intramuscular fat (marbling; within the muscle) Color of the fat (white vs. yellow),NORMAL AND DARK-CUTTING BEEF,Dikeman, 1993,CONSUMERS VISUAL PREFERENCE FOR NORMAL- VS. DARK-COLORED FRESH BEEF STEAKS a,Consumers were asked to visually evaluate fresh strip loin steaks

3、 that differed in color: dark vs. normal (bright cherry-red). Sixty-eight percent of the participants preferred normal color and were willing to pay a premium of $0.23 per kg ($1.69 vs. $1.46). a Calkins et al. 2000. J. Anim. Sci. 78 (Suppl. 1):23.,PRE-HARVEST STRESS AND DARK CUTTNG BEEF a,Factors t

4、hat affect the occurrence of dark cutting beef are: Gender (heifers are more excitable than steers) Stressful cattle handling procedures Mixing cattle from different pens or locations Long transportation and holding times Large fluctuations in temperature prior to harvest a Scanga et al. 1998. J. An

5、im. Sci. 76:2040.,WHAT IS BEEF QUALITY?,In cooked beef, it is: Flavor Juiciness Tenderness,PALATABILITY OF COOKED BEEF,Palatability of cooked beef is determined by the combined effects of flavor, juiciness, and tenderness. Flavor intensity is related to the amount of intramuscular fat (marbling), an

6、d the compounds that arise from muscle changes during postmortem aging. Juiciness is determined by amounts of intramuscular moisture and marbling that remain in the muscle after cooking. Tenderness is determined by extent of postmortem muscle fiber shortening and breakdown, and the amounts of moistu

7、re, marbling, and intact connective tissue left after cooking.,CONSUMERS PERCEPTION OF THE IMPORTANCE OF SENSORY ATTRIBUTES,Miller et al., 1995,Frequency, %,CONSUMER PURCHASE PREFERENCE OF STEAKS VARYING IN TENDERNESS WHEN PRICED ACCORDINGLY,Boleman et al., 1995,Purchase preference, %,TENDERNESS,PRE

8、-HARVEST FACTORS THAT AFFECT BEEF TENDERNESS,BREEDS,Research has shown that British breeds are more tender than Continental breeds and Bos indicus breeds are less tender than either Continental or British breeds. In commercial crossbreeding programs, acceptable tenderness can usually be achieved by

9、marketing progeny that have: A minimum of 1/2 British breeding A maximum of 1/4 to 3/8 Bos indicus breeding,0,1,2,3,4,5,6,7,8,9,0,50,100,150,200,Days on Feed,Shear Force (Kg),(From May et al., 1992),EFFECT OF AGE ON BEEF TENDERNESS,When harvested at an equal fat thickness endpoint within an age rang

10、e of 9 to 30 months, there is a tendency for younger cattle to be more tender than older cattle As cattle advance in age beyond 30 months, tenderness declines rapidly, because of increasing amounts of connective tissue.,EFFECT OF RESPIRATORY DISEASE ON BEEF QUALITY a,Steers having no lung lesions sh

11、owed the following advantages over those having lung lesions due to respiratory disease: Significantly higher marbling scores and USDA quality grades Significantly improved shear force (tenderness) values a Gardner et al. 1998. Oklahoma State Univ. Research Report.,EFFECT OF INJECTION SITE LESIONS O

12、N BEEF TENDERNESS,Intramuscular injection of various biological and pharmaceutical compounds into the outside round and top sirloin butt resulted in significantly less tender (P .001) steaks from these muscles. The toughened area covered a radius of 3 inches (7.6 cm) from the center of the injection

13、 site lesion. Trimming of the affected tissue represented a loss of nearly $6 per animal. SOURCE: Colorado State Univ. Beef Program Reports (1993, 1995, 1996, 1997, 1999),EFFECT OF TEMPERAMENT ON ANIMAL WEIGHT GAIN AND BEEF QUALITY,Colorado State University researchers scored 531 feedlot cattle for

14、temperament (1=calm; 5=extremely excitable). As temperament scores increased: There was a highly significant (P .001) decrease in average daily gain. There was a significant (P .01) increase in the incidence of dark cutting beef. There was a highly significant (P .001) decrease in meat tenderness as

15、 evaluated by shear force. SOURCE: Voisinet et al. 1997. Meat Science 46(4):367,HOW IMPORTANT IS MARBLING (INTRAMUSCULAR FAT)?,WHAT IS THE ROLE OF MARBLING?,Research has shown that marbling accounts for only about 10% of the variation in beef tenderness.However, recent studies show that some consume

16、rs credit higher-marbled beef with being significantly more tender than it really is: It appears that these consumers prefer the flavor of higher-marbled beef above and beyond any tenderness that exists. Therefore, it could be very important to identify those consumers who prefer high-marbling flavo

17、r vs. those who prefer low-marbling flavor.,RELATIONSHIP BETWEEN QUALITY GRADE AND TENDERNESS OF RETAIL STRIP LOIN STEAKS (Sensory Evaluation Panel),RELATIONSHIP BETWEEN QUALITY GRADE AND TENDERNESS OF RETAIL LOIN STEAKS,“Quality grades were reasonably effective for categorizing retail loin steaks a

18、ccording to differences in tenderness when quality grade ranged from Select to Prime, but were not effective for identifying tenderness differences between Select and Low Choice steaks (the narrow range in which over 80% of U.S. fed beef is graded).”SOURCE: George et al. 1999. J. Anim Sci. 77:1735,A

19、VERAGE HERITABILITY ESTIMATES FOR CARCASS TRAITS (AGE-CONSTANT) a,POTENTIAL CORRELATED RESPONSES TO SELECTION FOR MARBLING,Favorable: Decreased shear force (.39) Increased preweaning gain (.39)Unfavorable: Increased fat thickness (.37) Decreased ribeye area (.14) Decreased % retail product (.24) SOU

20、RCE:D.M. Marshall (1994); genetic correlations are in parentheses,BEEF QUALITY OF HEREFORD AND HEREFORD CROSS CATTLE VS. USDA CHOICE AND SELECT GRADE CARCASSES,An extensive study involving 1,000 Hereford and Hereford cross steers and heifers, 120 USDA Choice, and 120 USDA Select grade carcasses gave

21、 the following results: Hereford and Hereford cross carcasses quality graded 38% USDA Choice and 56% USDA Select. Hereford and Hereford crosses were equal to USDA Choice beef in tenderness ratings and superior to USDA Select. Hereford and Hereford crosses were superior in overall palatability rating

22、s to both USDA Choice and Select. SOURCE: Huffines (1992).,POSTWEANING EFFICIENCY AT VARIOUS MARKET ENDPOINTS (MARC),CAN WE DIRECTLY MEASURE TENDERNESS IN FRESH BEEF?,INSTRUMENTATION TO EVALUATE BEEF PALATABILITY,Swatland connective tissue probe MARC Tenderness Classification System Colorimeter Syst

23、em NIR (Near-Infrared Spectroscopy) Denver Research Institute Ultrasound System HunterLab BeefCam,HUNTERLAB BEEFCAM SYSTEM FOR EVALUATING BEEF PALATABILITY,Of those carcasses certified as tender using the BeefCam system: 98.6% were found to be tender by shear force evaluation 79.7% were rated as ten

24、der by a trained taste panel SOURCE: Belk (1999),“BeefCam technology is the most promising non-invasive technique ever identified for use in predicting palatability of cooked beef from measurements taken on the raw carcass.”,G.C. SmithColorado State Univ.,GENETIC SELECTION FOR BEEF CARCASS TRAITS,EF

25、FECTIVENESS OF STRATEGIES TO IMPROVE TENDERNESS a,THE FUTURE,EPDs/EBVs (Estimated Breeding Values) for tenderness will be available. Major genes for tenderness and other carcass traits will be identified. DNA testing of live cattle for carcass traits will be developed. Increased emphasis on muscling

26、 because of its impact on red meat yield. Multiple-trait selection technology will combine carcass, reproduction, and growth traits into a single profit index that can be tailored to the objectives of individual cattle breeders.,THE FUTURE,“I prefer the dreams of the future to the history of the past.”Thomas Jefferson,THE FUTURE,“Our real task is not to foresee the future, but to enable it.”Saint Exupery inWisdom of the Sands-,