There are several means of determining the tenderness of meat. Recently, a great deal of effort has been focused on connective tissue, or collagen, as a measure of tenderness. These foci have included biochemical determination of collagen types, the ratios of soluble and insoluble collagen, changes of collagen with age, and abundance of collagen.
The purpose of this study is to evaluate the abundance of collage as a means of differentiating levels of tenderness , using histology. Steaks taken from the bovine tenderloin, inside round, and bottom round (eye) were observed histologically using special stains for connective tissue. This method, compared with accepted methods of measuring tenderness, showed similar trends, but its use is limited

Adams, Rachael Anne

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Utah State University DigitalCommons@USU Undergraduate Honors Capstone Projects Honors Program 5-1998 The Influence of Connective Tissue in Meat Tenderness (A Histological and Comparative Study) Rachael Anne Adams Utah State University Follow this and additional works at: https://digitalcommons.usu.edu/honors  Part of the Dairy Science Commons, and the Meat Science Commons Recommended Citation Adams, Rachael Anne, "The Influence of Connective Tissue in Meat Tenderness (A Histological and Comparative Study)" (1998). Undergraduate Honors Capstone Projects. 906. https://digitalcommons.usu.edu/honors/906 This Thesis is brought to you for free and open access by the Honors Program at DigitalCommons@USU. It has been accepted for inclusion in Undergraduate Honors Capstone Projects by an authorized administrator of DigitalCommons@USU. For more information, please contact digitalcommons@usu.edu. THE INFLUENCE OF CONNECTIVE TISSUE IN MEAT TENDERNESS (A HISTOLOGICAL AND COMPARATIVE STUDY) Approved: by Rachael Anne Adams Thesis submitted in partial fulfillment of the requirements for the degree of UNIVERSITY HONORS WITH DEPARTMENTAL HONORS m Animal, Dairy, and Veterinary Sciences Thesis/Project Advisor Department Honors Advisor Director of Honors Program UTAH STATE UNIVERSITY Logan, UT 1998 THE INFLUENCE OF CONNECTIVE TISSUE IN MEAT TENDERNESS (A HISTOLOGICAL AND COMP ARA TNE STUDY) Approved: by Rachael Anne Adams Thesis submitted in partial fulfillment of th ; requirements for the degree of UNIVERSITY HONORS WITH DEPARTMENTAL HONORS m Animal, Dairy, and Veterinary Sciences Thesis/Project Advisor Department Honors Advisor Director of Honors Program UT AH STATE UNIVERSITY Logan, UT 1998 ABSTRACT There are several means of determining the tenderness of meat. Recently, a great deal of effort has been focused on connective tissue, or collagen, as a measure of tenderness. These foci have included biochemical determination of collagen types, the ratios of soluble and insoluble collagen, changes of collagen with age, and abundance of collagen. The purpose of this study is to evaluate the abundance of collage as a means of differentiating levels of tenderness , using histology. Steaks taken from the bovine tenderloin, inside round, and bottom round (eye) were observed histologically using special stains for connective tissue. This method, compared with accepted methods of measuring tenderness, showed similar trends, but its use is limited. INTRODUCTION Meat is generally sold at higher prices than other sources of protein (Wulf et al), therefore it is very important to the industry that methods can be found to more efficiently determine acceptable and unacceptable, or higher quality of acceptable carcasses. Many consumers desire and will pay the high price for a tender steak. These same individuals develop an ability to differentiate cuts by name and pricing. For example, a tenderloin may be priced at $7.99/lb,whereas, a top round $3 .49/lb, and an eye of round steak is $3. 89/lb; the cost/lb being an indication of how tender the steak should be in comparison to others. There have been several methods developed for determining tenderness in the meat industry both subjective and objective. Subjective measures such as the age of animals at the time of slaughter, marbling, meat color, and breed are fast and fairly good predictors of tenderness. However even within these divisions there is a great deal of variation. Further study and objective methods such as pH of muscle tissue has developed. The pricing of meat cuts shows and even deeper level of classification, however classification based on price is somewhat limited. To best study muscle tenderness it is important to understand the composition of meat. Steaks may be differentiated by fragmentation of muscle fibers, collagen solubility ratios, and other biochemical analysis, but the most common methods involve taste panels and tissue shear cutting force. A great deal of emphasis has been placed on the study of the connective tissue found within the muscle. This collagen not only functions in supporting the muscles and their movement with the bones but also surrounds individual fibers and muscle bundles. The strength and stability of this collagen increases with age, sexual maturity, and use of the particular muscle or muscle group. One very important factor is how much collagen is present in various cuts of meat. The more connective tissue (collagen), that is found within a group of fibers, the less tender the steak is. The purpose of this study is to see if quantitative histology is an effective method to predict tenderness in three beef steak cuts. MATERIALS AND METHODS Meat Sample. The steaks used for this study were obtained from an "A" maturity, select heifer. The heifer had a 600 lb dress weight with 4% KPH ( kidney-pelvic are) fat, slight marbling, light cherry red color score, and a yield grade of 3. Consecutive steaks were taken from the tenderloin, inside round, and eye of round for evaluation. All exterior fat was trimmed and the steaks were stored at -6 C0 for 7 days. On day 7 the steaks were removed and thawed at room temperature for approximately 7 hours, then tempered in a standard refrigerator at 4°C for 4 hours. Histology Evaluation. One cm3 samples of the tenderloin, top round and eye of the round were fixed in a 10% buffered formalin solution after which they were trimmed and prepared for sectioning. A longitudinal and cross-section were made of each sample. The tissues were stained with a standard H&E and a Van Giessen connective tissue stain. Light microscopy was used for quantitating collagen fibers at various chosen reference points. It was difficult to assure a representative reference point among the samples. Next, photos were taken of the slides at 40X and lO0X power. Photos were then labeled and scored for connective tissue. Two individuals made a blind judgement to classify the photos on the abundance of collagen in each of the three tissues. The photos were placed in order of most, moderate, and slight collagen. The histological evaluations produced identical results compared with the results of the taste panel and the Warner-Bratzler shear test procedures. Consistency and reproducibility needs to be further studied. Student Taste Panel. The steaks were cooked on an open grill to an internal temperature of approximately l 60°C. The temperature was monitored by a meat thermometer and all steaks were cooked for the same period of time. One in square pieces of each steak were served on sections of a plate which was divided into thirds. The samples were served warm to the panelists. The panelist were chosen from a class of pathology students and random participants of various backgrounds in terms of meat knowledge. The panelist were given a score sheet and asked to rate the different samples on a scale from 1 to 8; 1 being a poor score for the category and 8 the most acceptable. The categories consisted of tenderness, amount of connective tissue, flavor intensity, juiciness and overall quality. The scores were then evaluated for their means and standard deviations. Warner-Bratz/er Shear Evaluation. The steaks were cooked in the same manner as in the taste panel. Five cores were taken, one from each steak type. Each core was sheared once. The mean shear force was then calculated. The cores were taken both perpendicular to and at an angle to the muscle fibers. This contributed to the variability in scoring (Wheeler et al). RESULTS a. Crossection of the longissimus dorsi (tenderloin) at lO0X. Van Giessen connective tissue stain. b. Crossection of the top round steak at 1 00X. Van Giessen connective tissue stain. c. Crossection of the eye of round steak at 1 00X. Van Giessen connective tissue stain. Taste panel: N=l 7 Scale =l (Bad)--8 (Good) Mean score and SD Tenderloin Tenderness 6.65 ± .93 Amount ofC.T. 6.41 ± .94 Flavor 6.29 ± .77 Juiciness 6.18±.95 Total 25.53 Overall 6.53 ± .87 * SD =standard deviation Wamer-Bratzler shear force values lb/cm2 diameter (core) Tenderloin core 1 5.75 core 2 7 core 3 6 core 4 7.5 core 5 6 mean and SD* 6.45 ± .75 *N=5 Top Round Eye of Round 4.94 ± 1.75 4.76 ± 1.20 3.94 ± 1.75 5.06 ± 1.43 5.65 ± 1.32 5.47 ± .94 6.18±.95 4.76 ± 1.44 24.76 20.05 5.00 ± 1.69 5.24 ± 1.09 Top Round Eye of Round 8.5 8 8 8.5 5 6.5 4 10.5 9 11 6.9 ±2.25 8.9 ± 1.85 DISCUSSION General abundance of collagen as seen histologically showed the same trends of the other methods used. The cuts used for this study were chosen because they were generally known to have a larger difference. If a tenderloin, top loin, and ribeye were tested using this method, results would be more difficult and perhaps unattainable. To differentiate these closer cuts it is not the amount of collagen that makes the difference, but the kind. More specific collagen solubility methods are then required. There are presently 25 known types of collagen, each consisting of one or more specific alpha-chains. These distinct amino acid chains and their cross links determine the solubility of the collagen (Basic Medical Histology pp.108). Results for the taste panel and Wamer-Bratzler shear test methods were statistically insignificant for this study. However, with present information and standard deviations an appropriate sample size could be used to further study the implications of the tenderness variation in the differing cuts. ACKNOWLEDGMENT Dr. Stan Allen Dr. Darrin Cornforth Dr. Dick Whittier USU Diagnostic Lab REFERENCES Bailey, Allen J., Restall, David J., Sims, Trevor J., and Duance, Victor C. 1979. Meat Tenderness: Immunoflourescent Localization of the Isomorphic Forms of Collagen in Bovine Muscles of Varying Texture. J. Sci. Food Agric. 30:203-210. Bailey, Allen J. and Sims, Trevor J. 1977. Meat Tenderness: Distribution of Molecular Species of Collagen in Bovine Muscle. J. Sci. Food Agric. 28:565-570. Burson,)). E. and Hunt, M. C. 1986. Proportion of /collagen Types I and III in Four Bovine Muscles Differing in Tenderness. J. of Food Science. 51:51-53 Cross, H. R., Carpenter, Z. L., and Smith, G. C. 1973. Effects oflntramuscular Collagen and Elastin on Bovine Muscle Tenderness. J. of Food Science. 38:998-1003. Davis, G. W., Dutson, T. R., Smith, G. C., and Carpenter, Z.L. 1980. Fragmentation Procedure fro Bovine Longissimus Muscle as an Index of Cooked Steak Tenderness. J. Food Science. 45:880-884. Field, R., McCormick, R., Balasubramanian, V., Sanson, D., Wise, J., Hixon, D., Riley, M., and Russell, W. 1997. Tenderness Variation among Loin Steaks from A and C Maturity Carcasses of Heifers Similar in Chronological Age. J. Anim. Sci. 75:693-699. Huffman, K.L., Miller, M.P., Hoover, L.C., Wu, D. K., Britten, H.C., and Ramsey, C. B. 1996. Effect of Beef Tenderness on Consumer Satisfaction with Steaks Consumed in the Home and Restaurant. J. Anim. Sci. 74:91-97. Kessel, Richard G. 1998. Medical Histology text. Oxford Univ. Press. pp 108, table 5.2. Light, Nicholas, Voyle, Charles, and Champion, Anne. 1984. Food Group (Meat Panel) Symposium Connective Tissue in Meat and Meat Products--What are the practical implications. J. Sci. Food Agric. 35: 1261-1267 Olsen, Dennis G., Parrish Jr., F.C., and Stromer, M.H. 1976. Myofibril Fragmentation and Shear Resistance of Three Bovine Muscles During Postmortem Storage. J. of Food Science. 41: 1036-1041. Wheeler, T.L., Shackelfore, S.D., and Koohmaraie, M. 1996. Sampling, Cooking, and Coring Effects on Warner-Bratzler Shear Force Values in Beef J. Anim. Sci. 74:1553-1562. Wu, F.Y., Dutson,T.R., Valin, C., Cross, HR, and Smith,S. B. 1985. Aging Index, Lysosomal Enzyme Activities, and Meat Tenderness in Muscle from Electrically Stimulated Bull and Steer Carcasses. J. of Food Science. 50: 1025-1028. Wu, F.Y., Dutson,T. R., and Smith,S.B.1985. A Scanning Electron Microscopic Study ofHeat-Induced Alterations in bovine Connective Tissue. J. of Food Science. 5 0: 1041-1044. Wulf, Duane M, O'Conner, Shannon F., Tatum, J. Daryl, and Smith, Gary C. 1997. Using Objective Measures of Muscle color to Predict BeefLongissimus Tenderness. J. Anim. Sci. 75:684-692. 

The Influence of Connective Tissue in Meat Tenderness (A Histological and Comparative Study)

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The Influence of Connective Tissue in Meat Tenderness (A Histological and Comparative Study)

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