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Use of Ionic Compounds Infusion to Improve Meat Tenderness:
A  Review


Paolo Polidori

Francesco Fantuz


Dipartimento di Scienze Veterinarie, Universitą di Camerino, Via Circonvallazione 93, 62024 Matelica (MC), Italy


KEY WORDS: Meat tenderization, ionic compounds, calpain


The present work is an attempt to review and update what is known about the effects of ionic compounds injection of carcasses of meat animals, including the effects on meat tenderness and meat sensorial characteristics. Pre-rigor ionic compound injection to change the rate of glycolysis, rate and state of contraction, and rate of proteolysis appears to be a feasible method of postmortem meat tenderization.


Consumers consider meat tenderness the most important palatability trait of meat quality,1 and its variability is an area of major concern in the meat industry.2-4 Although the practice of storing meat after the death of an animal to improve its texture was probably established long ago, its beneficial effects were not recognized until the beginning of this century.5 Later, proteolyisis of muscle proteins was proposed and has since been considered the primary mechanism of meat tenderization.6

Meat tenderness varies considerably among species, among animals within a species, and among different muscles held for different times post mortem.7 Although the connective tissue content is responsible for some of this variation, the virtual lack of change in this component during postmortem storage while considerable tenderization occurs has led to the conclusion that the proteins in the muscle myofibril primarily control meat texture.8 The changes in myofibrillar proteins after death are believed to be mainly proteolytic in nature; most efforts to date have focused on identifying the proteases involved and the substrates altered.5,9,10

Postmortem proteolysis of the major myofibrillar proteins has been found to be negligible. The disappearance of the troponin T band and the appearance of a 30,000 Da band on sodium dodecyl sulphate polyacrylamide gel electrophoreisis (SDS-PAGE) has been documented, and the extent of this change has been shown to correlate to meat tenderness.11-13 However, although postmortem aging normally improves muscle tenderness, in some muscles the 30,000 Da component does not develop during aging. For this reason, Greaser and Fritz8 stated that the degradation of this protein is a primary event that results in the weakening of the myofibril structure but rather a marker for some other change.

Desmin, an intermediate filament protein believed to link the Z-lines of adjacent myofibrils, decreases rapidly after death. This process has been suggested as the reason for the reduction in sarcomere alignment of adjacent myofibrils that occurs after death.14

This review focuses on the effects of ion injection on meat tenderness. First, the enzymatic mechanisms of meat tenderization are summarized; second, some properties of the calpain system are discussed; and finally, the results obtained in previous experiments regarding the effect of ion injection on tenderizing meat are described.

Meat Tenderization

Consumers consider meat tenderness to be the most important palatability trait of meat quality.15 Different factors have been reported to affect meat tenderness, such as animal age, muscle pH and temperature, sarcomere length, amount and type of collagen, and muscle fiber type and size.4,5,16-18 With regard to these factors, some authors19,20 found that the intensity and rate of these modifications are not only species dependent but also, within a given species, muscle dependent.

It is well known that meat tenderness increases gradually during postmortem storage (Table 1), and it is generally accepted that degradation of myofibrillar proteins and structure disruption by endogenous proteases are responsible for this postmortem tenderness improvement.5,9,10,21-23 During postmortem storage of carcasses, numerous changes occur in skeletal muscle, some of which result in the loss of tissue integrity that translates into improved meat tenderness (Table 2).

To further substantiate the argument that proteolysis is the principal reason for meat tenderization during postmortem storage (Table 3), some authors24,25 have also found that the major reason for the observed differences in meat tenderness between Bos taurus (tender) and Bos indicus (tough) breeds of cattle is the reduced rate of myofibrillar protein degradation during postmortem storage. Also, differences in the rate of postmortem tenderization and proteolysis in skeletal muscle from pigs, sheep, and cattle were apparently because of the differences in the rate of myofibrillar protein degradation. The results obtained in these studies clearly indicate that proteolysis of key myofibrillar proteins is the principal reason for the ultrastructural changes in skeletal muscle that result in tenderization.

Enzymatic Mechanisms
of Meat Tenderization

In living muscles, intracellular protein degradation is mediated by a number of different endogenous proteolytic enzymes.5 Because most changes occurring in the course of meat tenderization are currently believed to be the result of proteolysis, every proteinase located inside muscle cells could be a potent contributor to meat aging and must be considered in this context.

In the proteolytic systems detected in skeletal muscle, 2 proteinases have been noted that are able to degrade the myofibrillar proteins. These proteinases are calcium-dependent cysteine proteinases located in the cellular cytosol, calpain I and calpain II. They are active at micromolar (50 to 70 µmol) and millimolar (1 to 5 mmol) concentrations of Ca2+ respectively.26 The calcium-dependent proteases, calpain I and calpain II, also referred to as µ-calpain and m-calpain,9,27 have an optimum pH of 7.528 and have been shown to degrade Z-disk, troponin-T, and desmin. The calpain proteolytic system also includes a tissue-specific calpain, calpain 3 or nCL-1.29 Although calpain 3 has 10-fold more mRNA in muscle cells than calpain I or calpain II, the calpain 3 enzyme has never been identified.30 Other proteinases have been isolated, such as cathepsins B, H, and L,31,32 but their importance to meat tenderization is not completely clear.33,34

Because endogenous protein inhibitors may constitute a powerful regulatory system for muscle proteinases, interest in their identification and characterization has increased markedly. A specific calpain inhibitor called calpastatin has been isolated from muscles of various animal species.35-38 Some properties of the calpain system are listed in Table 4.

Calpain Activity and
Postmortem Tenderization

After incubating muscle strips in a Ca2+-containing solution, some authors discovered the total degradation of Z-disks.39,40  From that observation, efforts were begun to identify the Ca2+-activated factors (called CAF at that time) responsible for this degradation. However, even before CAF had been completely purified, it was shown that muscles with more CAF activity underwent a greater degree of postmortem tenderization than muscles with less CAF activity.41 Both CAF treatment and postmortem storage resulted in the appearance of several polypeptide fragments migrating in the 30,000-Da range in SDS-PAGE.

Since these early observations, a great deal of evidence has accumulated indicating that the calpains have an important role in postmortem tenderization (Table 5), and many studies have focused attention on this role.9,22,42-46 This evidence has led to the prevailing view that the calpains are responsible for 90% or more of the tenderization that occurs during postmortem storage,43 and that, furthermore, this tenderization is the direct result of calpain's ability to degrade Z-disks in skeletal muscle.

Skeletal muscle calpains, which have similar native molecular weights as 110 kDa,47 dissociate into 2 subunits of 80 and 30 kDa by SDS-PAGE. The active site containing a cysteine residue is located in domain II of the 80-kDa subunit, but the function of the 30-kDa unit is unknown.48 Cloning and sequencing studies have shown that calpain I and calpain II originate from different genes, with approximately 52% homology between their amino acid sequences.49 There are no clearly documented major differences in the catalytic properties of the calpains other than their respective calcium requirements; they cleave the same proteins and have similar cleavage site specifities.47

The enzymes involved in postmortem proteolysis have been the subject of much debate; however, it is now generally accepted that calpain I (also called µ-calpain) is the major enzyme involved.28,50 The calcium concentration in postmortem muscle could reach 150 µmol,51 which is sufficient to activate calpain I but insufficient for calpain II activity.9 The activity of calpain I is mostly regulated by calpastatin, its endogenous inhibitor.50 Levels of calpastatin in muscle vary considerably among species,52,53 breeds,24,54,55 and muscles.56,57 The ratio of calpastatin:calpain I is about 4:1, 2.5:1, and 1.5:1 in beef, lamb, and pork muscle, respectively.4

An obstacle to establishing the role of calpains in meat tenderization is that the activity of the calpain-calpastatin system is measured in vitro but the in situ activity is what dictates the rate of proteolysis and tenderization.58 Unfortunately, there is no method of measuring in situ activities. To circumvent this problem, Dransfield51,59 developed a computer model that estimates the postmortem changes in the in situ activities of the calpains and the associated changes in meat tenderization. The principle of the model is to calculate the accompanying pH and calcium ions profiles from the postmortem temperature profiles of meat. These profiles are subsequently used to estimate the in situ activities of calpains and calpastatin based on their in vitro activities.

Variations in calpain activity, rather than in sarcomere length, are believed to cause toughness variation in thaw rigor muscle.60 Reduced proteolysis is therefore a factor that should be considered in understanding the mechanisms of cold-shortening toughness.61

Meat Tenderization Via Prerigor Injections of
Ionic Compounds

Both Webster's New World Dictionary of the American Language62 and Dorlands's Illustrated Medical Dictionary63 define infusion similarly as the introduction of a solution into the body, specifically into a vein, and perfusion as the act of pouring (such as a liquid) over or through an organ or a tissue. The American Heritage Dictionary of the English Language64 specifically defines infusion as "the introduction of a solution into a vein" and defines perfusion as "the injection of a fluid into an artery in order to reach tissues." When citing other works in this article, we have used their original term, although we believe that infusion should refer to the introduction of a solution via a vein and perfusion should refer to the introduction of a solution via an artery.

Infusion or perfusion of compounds to change the rate of glycolysis, rate and state of contraction, and rate of proteolysis appear to be feasible methods of manipulating the postmortem tenderization process in meat.37,65-67 It was reported in the mid1950s that infusion of bovine carcasses with salt solutions caused a considerable improvement in tenderness.36 Salts generally influence the functional properties of meat products68 and are believed affect contraction and shortening, protein-protein interactions, protein solubility, proteolytic enzyme activity, and lattice swelling.69

Beekman et al70 and Geesink et al36 reported a positive effect of sodium chloride (NaCl) or NaCl and phosphate treatment on meat tenderness. Consequently, it was suggested that NaCl injection may improve tenderness in different ways, such as dissociation of actomyosin or solubilization of proteins from myofilaments.

Stevenson-Barry and Kauffman71 reported that injection of either NaCl or sodium pyrophosphate (NaPPi) into hot-boned muscles reduces cold-induced toughening. They suggested that the mechanism did not involve inhibition of contraction because sarcomere lengths were not changed. Furthermore, because both NaCl and NaPPi injections into muscles improved tenderness, the authors suggested that ionic strength was one of the important reasons for improving tenderness.

Polyphosphates, including pyrophosphate, triphosphate, and metaphosphate, have high buffering capacity at neutral to alkaline pH (pH 6.5 to 9.0) due to their polyanionic characteristics.72 Injection or infusion of pyrophosphates increased meat pH and improved meat quality by assisting solubilization of myosin and increasing uptake and retention of water.73

Sodium chloride is a useful compound for meat because it is a well-known food additive, has long been used for its positive effects on preservation and flavor of meat, and is not considered an unfamiliar chemical additive such as NaPPi or calcium chloride (CaCl2). Moreover, unlike CaCl2 and other salts, NaCl does not cause bitterness.37 In fact, CaCl2 is not only salty, it also has a metallic, bitter flavor when used at the same level as NaCl. It is not surprising that trained sensory panelists can detect it in meat.74 However, Offer and Knight73 suggested that a combination of NaCl and NaPPi produced a synergistic effect at lower salt concentrations.

The results obtained in a recent study75 indicated that infusion of beef carcasses with CaCI2 accelerated postmortem tenderization. The direct action of calcium ions was described by Takahashi.76 Calcium ions have a dual function in postmortem muscle; the rise of sarcoplasmic calcium ion concentrations to 3 to 5 mmol induces rigor contraction, and the further rise of the calcium ion concentration to 0.1 mmol weakens the structures of myofibrils, desmin intermediate filaments, and probably the endomysium and perimysium, thereby tenderizing the meat. However, Table 6 summarizes the different ionic compounds injected before rigor in carcasses of meat animals in previous experiments. The salt most frequently used has been calcium chloride, and the most common salt concentration was 0.3 mol. Calcium chloride infusion was recently shown77 to be an effective method of reducing toughness also in pork meat.

Other studies1,78,79 have been performed to establish the conditions required to improve meat tenderness by using calcium chloride marination, and consequently to reduce the time required for the postmortem tenderization. The results obtained by Gonzalez et al1 showed that calcium chloride marination was effective in increasing tenderness and in reducing the postmortem storage time necessary to achieve an acceptable level of tenderness in beef muscle Cutaneus trunci. The results obtained by Whipple and Koohmaraie79 showed that the improvement in tenderness was due by the activation of calpain II, also called m-calpain.


Many methods have been suggested in the past to change the pre-rigor properties of muscles in an attempt to improve meat quality. The simplest and best documented method of improving, but not eliminating, the inconsistency of meat tenderness is to ensure that meat is not consumed before an adequate aging period. To maximize consistency in tenderness, beef, lamb, and pork should be aged for 10 to 14, 7 to 10, and 5 days, respectively.4 However, use of ionic compound injection by the meat industry would also reduce the variation found in meat tenderness, reducing the need to depend on an adequate aging period as the primary factor for reducing meat toughness.


1. Gonzalez CB, Salitto VA, Carduza FJ, et al: Effect of calcium chloride marination on bovine Cutaneus trunci muscle. Meat Sci 57:251-256, 2001.

2. Morgan JB, Savell JW, Hale DS, et al: National beef tenderness survey. J Anim Sci 69:3274-3283, 1991.

3. Smith GC, Savell JW, Clayton RP, et al: The final report of the national beef quality audit. Colorado State University, Ft. Collins and Texas A & M University, College Station, USA. 1992.

4. Koohmaraie M: Biochemical factors regulating the toughening and tenderization process of meat. Meat Sci 43(Suppl):S193-S201, 1996.

5. Ouali A: Meat tenderization: possible causes and mechanisms: A review. J Muscle Foods 1:129-165, 1990.

6. Hoagland R, McBride CN, Powick WC: Changes in fresh beef during cold storage above freezing. Washington: United States Department of Agriculture Bulletin. 1917.

7. Polidori P, Lee S, Kauffman RG, Marsh BB: Low voltage electrical stimulation of lamb carcasses: Effects on meat quality. Meat Sci 53:179-182, 1999.

8. Greaser ML, Fritz JD: Post-mortem changes in myofibrillar proteins in relation to meat texture. In: Expression of Tissue Proteinases and Regulation of Protein Degraddation as Related to Meat Quality. The Netherlands: Audet Tijdshriften; pp. 293-309. 1995.

9. Koohmaraie M: The role of Ca2+-dependent proteases (calpains) in post mortem proteolysis and meat tenderness. Biochimie 74:239-245, 1992.

10. Koohmaraie M: Muscle proteinases and meat aging. Meat Sci 36:93-104, 1994.

11. Koohmaraie M, Babiker AS, Merkel RA, Dutson TR: Role of Ca++-dependent proteases and lysosomal enzymes in postmortem changes in bovine skeletal muscle. J Food Sci 53:1253-1257, 1988.

12. Paterson BC, Parrish FC Jr., Stromer MH: Effects of salt and pyrophosphate on the physical and chemical properties of beef muscle. J Food Sci 53:1258-1265, 1988.

13. Parr T, Sensky PL, Scothern GP, et al: Relationship between skeletal muscle-specific calpain and tenderness of conditioned porcine longissimus muscle. J Anim Sci  77:661-668, 1999.

14. Lawrie RA: Meat Science, 4th Ed. Oxford: Pergamon Press, 1985.

15. Cross HR, Savell JW, Francis JJ: National consumer retail beef study. Proceedings of Reciprocal Meat Conference, Chicago, IL, 1986.

16. Hostetler RL, Link BA, Landmann WA, Fitzhugh HA: Effect of carcass suspension on sarcomere length and shear force of some major bovine muscles. J Food Sci 37:132-137, 1972.

17. Marsh BB: The basis of tenderness in muscle foods. J Food Sci 42:295-297, 1977.

18. Dransfield E: Optimisation of tenderisation, ageing and tenderness. Meat Sci 36:105-121, 1994.

19. Dransfield E, Jones RC: Relationship between tenderness of three muscles. J Sci Food Agricult 32:300-304, 1981. 

20. Ouali A: Variation between muscles of the effect of aging on myofibrilar ATPase activity. Sci Aliments 1:1-6, 1981.

21. Penny IF: The enzymology of conditioning. In: Lawrie RA, ed: Developments in Meat Science. London: Elsevier Applied Science Publishers; pp. 115-143. 1980.

22. Dransfield E: Modeling post-mortem tenderisation: III: Role of calpain I in conditioning. Meat Sci 31:85-94, 1992.

23. Asghar A, Bhatti AR: Endogenous enzymes in skeletal muscle: Their significance in muscle physiology and during post mortem aging events in carcasses. Adv Food Res 31:343-451, 1987.

24. Whipple G, Koohmaraie M, Dikeman ME, et al: Evaluation of attributes that affect longissimus muscle tenderness in Bos taurus and Bos indicus cattle. J Anim Sci 68:2716-2728, 1990.

25. Shackelford SD, Koohmaraie M, Miller MF, et al: An evaluation of tenderness of the longissimus muscle of Angus by Hereford versus Brahman crossbred heifers. J Anim Sci 69:171-177, 1991.

26. Hortņs M, Gil M, Sąrraga C: Effect of calpain and cathepsin activities on myofibrils from porcine longissimus muscle during conditioning of normal and exudative meat. Sci Aliments 14:503-515, 1994.

27. Valin C: Les proteases des viandes. In: Mouranche A, Costes C, eds: Hydrolases et depolymerases: enzymes d'interet industriel. Paris: Gauthier-Villars; pp. 279-314. 1985.

28. Koohmaraie M, Schollmeyer JE, Dutson TR: Effect of low-calcium-requiring activated factor on myofibrils under varying pH and temperature conditions. J Food Sci 51:28-32, 1986.

29. Suzuki K, Sorimachi H, Yoshizawa T, et al: Calpain: novel family members, activation and physiological function. Biol Chem Hoppe-Seyler 376:523-529, 1995.

30. Koohmaraie M, Kent MP, Shackelford SD, et al: Meat tenderness and muscle growth: Is there any relationship? Meat Sci 62:345-352, 2002.

31. Goll DE, Otsuka Y, Nagainis PA, et al: Role of muscle proteinases in maintenance of muscle integrity and mass. J Food Biochem 7:137-177, 1983.

32. Zeece MG, Katoh K: Cathepsin D and its effects on myofibrillar proteins: a review. J Food Biochem 13:157-178, 1989.

33. Johnson MH, Calkins CR, Huffman RD, et al: Differences in cathepsin b + L and calcium-dependent protease activities among breed type and their relationship to beef tenderness. J Anim Sci 68:2371-2379, 1990.

34. Dransfield E, Etherington DJ, Taylor MAJ: Modelling post-mortem tenderisation: II: Enzyme changes during storage of electrically stimulated and non-stimulated beef. Meat Sci 31:75-84, 1992.

35. Koohmaraie M, Seideman SC, Schollmeyer JE, et al: Effect of post-mortem storage on Ca++- dependent proteases, their inhibitor and myofibril fragmentation. Meat Sci 19:187-196, 1987.

36. Geesink GH, Smulders FJM, Van Laack R: The effects of calcium-, sodium- and zinc-chlorides treatment on the quality of beef. Sci Aliments 14:485-502, 1994.

37. Lee S, Stevenson-Barry J, Kauffman RG, Kim BC: Effect of ion fluid injection on beef tenderness in association with calpain activity. Meat Sci 56:301-310, 2000.

38. Polidori P, Trabalza Marinucci M, Fantuz F, et al: Tenderization of wether lambs meat through pre-rigor infusion of calcium ions. Meat Sci 55:197-200, 2000.

39. Goll DE, Arakawa N, Stromer MH, et al: Chemistry of muscle proteins as a food. In: Brisky EJ, Cassens RG, Marsh BB, Eds: The Physiology and Biochemistry of Muscle as a Food. Madison, WI: The University of Wisconsin Press; pp. 755-880. 1970.

40. Busch WA, Stromer MH, Goll DE, Suzuki A: Ca2+-specific removal of Z-lines from rabbit skeletal muscle. J Cell Biol 52:367-372, 1972.

41. Goll DE, Stromer MH, Olson DG, et al: The role of myofibrillar proteins in meat tenderness. Proceedings of the Meat Industry Research Conference, Arlington, VA, 1974.

42. Goll DE, Thompson VF, Taylor RG, Christiansen JA: Role of the calpain system in muscle growth. Biochimie 74:225-237, 1992.

43. Goll DE, Taylor RG, Christiansen JA, Thompson VF: Role of proteinases and protein turnover in muscle growth and meat quality. Proceedings of the Reciprocal Meat Conference, Knoxville, 1992.

44. Morgan JB, Wheeler TL, Koohmaraie M, et al: Meat tenderness and the calpain proteolytic system in longissimus muscle of young bulls and steers. J Anim Sci 71:1471-1476, 1993.

45. Taylor GR, Geesink GH, Thompson VF, et al: Is Z-disk degradation responsible for postmortem tenderization? J Anim Sci 73:1351-1367, 1995.

46. Boehm ML, Kendall TL, Thompson VF, Goll DE: Changes in the calpains and calpastatin during postmortem storage of bovine muscle. J Anim Sci 76:2415-2434, 1998.

47. Hughes MC, Geary S, Dransfield E, et al: Characterization of peptides released from rabbit skeletal muscle troponin-T by m-calpain under conditions of low temperature and high ionic strength. Meat Sci 59:61-69, 2001.

48. Carafoli E, Molinari M: Calpain: A protein in search of a function. Biochemic Biophys Res Comm 247:193-203, 1998.

49. Goll DE, Kleese WC, Szpacenko A: Skeletal muscle proteases and protein turnover. In: Campion DR, Hausman GJ, Martir RJ, eds: Animal Growth Regulation New York: Plenum Publisher; pp. 141-182. 1989.

50. Geesink GH, Koohmaraie M: Postmortem proteolysis and calpain/calpastatin activity in callypige and normal lamb biceps femoris during extended postmortem storage. J Anim Sci 77:1490-1501, 1999.

51. Dransfield E: Modelling post-mortem tenderisation: IV: Role of calpains and calpastatin in conditioning. Meat Sci 34:217-234, 1993.

52. Ouali A, Talmant A: Calpains and calpastatin distribution in bovine, porcine and ovine skeletal muscle. Meat Sci 28:331-348, 1990.

53. Koohmaraie M, Whipple G, Kretchmar DH, et al: Postmortem proteolysis in longissimus muscle from beef, lamb and pork. J Anim Sci 69:617-624, 1991.

54. Shackelford SD, Koohmaraie M, Whipple G, Wheeler TL, et al: Predictors of beef tenderness: development and verification. J Food Sci  56:1130-1140, 1991.

55. Shackelford SD, Koohmaraie M, Cundiff LV, et al: Heritabilities and phenotypic and genetic correlations for bovine postrigor calpastatin activity, intramuscular fat content, Warner-Bratzler shear force, retail product yield, and growth rate. J Anim Sci 72:857-863, 1994.

56. Koohmaraie M, Seideman SC, Schollmeyer JE, et al: Factors associated with the tenderness of three bovine muscles. J Food Sci 53:407-410, 1988.

57. Geesink GH, Ouali A, Smulders FJM: Tenderisation, calpain/calpastatin activities and osmolality of 6 different beef muscles. Proceedings of the 38th International Congress of Meat Science and Technology. Clermont Ferrand, 1992.

58. Morton JD, Bickerstaffe R, Kent MP, et al: Calpain-calpastatin and toughness in M. longissimus from electrically stimulated lamb and beef carcasses. Meat Sci 52:71-79, 1999.57. Dransfiled E: Calpains from thaw rigor muscle. Meat Sci 43:311-320, 1996.

59. Dransfield E: Modelling post-mortem tenderisation: V: Inactivation of calpains. Meat Sci 37:391-409, 1994.

60. Dransfield E: Calpains from thaw rigor muscle. Meat Sci 43:311-320, 1996.

61. Zamora F, Chaib F, Dransfield E: Calpains and calpastatin from cold-shortened bovine M. longissimus lumborum. Meat Sci 49:127-133, 1998.

62. Webster's New World Dictionary of the American Language. New York: World Publishing; 1972.

63. Dorlands Illustrated Medical Dictionary, 27th Ed. Philadelphia: WB Sanders; 1988.

64. American Heritage Dictionary of the English Language. Boston: Houghton Mifflin; 1980.

65. Koohmaraie M, Whipple G, Crouse JD: Acceleration of postmortem tenderization in lamb and Brahman-Cross beef carcasses through infusion of calcium chloride. J Anim Sci 68:1278-1283, 1990.

66. Morgan JB, Miller RK, Mendez FM, et al: Using calcium chloride injection to improve tenderness of beef from mature cows. J Anim Sci 69:4469-4476, 1991.

67. Wheeler TL, Koohmaraie M, Crouse JD: Effects of calcium chloride injection and hot boning on the tenderness of round muscles. J Anim Sci 69:4871-4875, 1991.

68. Hamm R: Post mortem breakdown of ATP and glycogen in ground muscle: A review. Meat Sci 1:15-39, 1977.

69. Stevenson-Barry JM: Tenderization of beef muscle by injection of salts. PhD Thesis. Madison, WI: University of Wisconsin. 1996.

70. Beekman DD, Hu-Lonergan EJ, Parrish FC Jr., et al: The effect of calcium chloride, sodium chloride and phosphate on various quality attributes of beef muscle. Proceedings of Reciprocal. Meat Conference, Chicago, IL, 1994.

71. Stevenson-Barry JM, Kauffman RG: Tenderization of muscle via pre-rigor injections of ions. Proceedings of the 41st International Congress of Meat Science and Technology, San Antonio, 1995.

72. Carpenter JA, Saffle RL, Kamstra LD: Tenderization of beef by pre-rigor infusion of a chelating agent. Food Technol 13:197-198, 1961.

73. Offer G, Knight P: The structural basis of water-holding in meat: Part 1. General principles and water uptake in meat processing. In: Lawrie RA, ed: Developments in Meat Science. London: Elsevier Applied Science Publishers; pp. 63-171. 1988.

74. Wheeler TL, Koohmaraie M, Shackelford SD: Effect of postmortem injection time and postinjection aging time on the calcium-activated tenderization process in beef. J Anim Sci 75:2652-2660, 1997.

75. Polidori P, Trabalza Marinucci M, Fantuz F, Polidori F: Post mortem proteolysis and tenderization of beef muscle through infusion of calcium chloride. Anim Res 50:223-226, 2001.

76. Takahashi K: Structural weakening of skeletal muscle tissue during post-mortem ageing of meat: The non-enzymatic mechanism of meat tenderization. Meat Sci 43:S67-S89, 1996.

77. Rees MP, Trout GR, Warner RD: Effect of calcium infusion on tenderness and ageing rate of pork m. longissiumus thoracis et lumborum after accelerated boning. Meat Sci 61:169-179, 2002.

78. Taylor MAJ, Etherington DJ: The solubilization of myofibrillar proteins by calcium ions. Meat Sci 29:211-219, 1991.

79. Whipple G, Koohmaraie M: Calcium chloride marination effects on beef steak tenderness and calpain proteolytic activity. Meat Sci 33:265-275, 1993.

80. Goll DE, Thompson VF, Taylor RG, Ouali A: The calpain system and skeletal muscle growth. Can J Anim Sci 78:503-512, 1998.

81. Koohmaraie M, Babiker AS, Schroeder AL, et al: Acceleration of postmortem tenderization in ovine carcasses through activation of Ca2+-dependent proteases. J Food Sci 53:1638-1641, 1988.

82. Koohmaraie M, Crouse JD, Mersmann HJ: Acceleration of postmortem tenderization in ovine carcasses through infusion of calcium chloride: effect of concentration and ionic strength. J Anim Sci 67:934-942, 1989.

83. Koohmaraie M: Inhibition of postmortem tenderization in ovine carcasses through infusion of zinc. J Anim Sci 68:1476-1483, 1990.

84. Koohmaraie M, Shackelford SD: Effect of calcium chloride infusion on the tenderness of lambs fed a b-adrenergic agonist. J Anim Sci 69:2463-2471, 1991.

85. St.Angelo AJ, Koohmaraie M, Crippen KL, Crouse J: Acceleration of tenderization/inhibition of warmed-over flavor by calcium chloride-antioxidant infusion into lamb carcasses. J Food Sci 56:359-362, 1991.

86. Farouk MM, Price JF, Salih AM, Burnett RJ: The effect of postexsanguination infusion of beef on composition, tenderness and functional properties. J Anim Sci 70:2773-2778, 1992.

87. Wheeler TL, Crouse JD, Koohmaraie M: The effect of postmortem time of injection and freezing on the effectiveness of calcium chloride for improving beef tenderness. J Anim Sci 70:3451-3457, 1992.

88. Wheeler TL, Koohmaraie M, Lansdell JL, et al: Effects of postmortem injection time, injection level, and concentration of calcium chloride on beef quality traits. J Anim Sci 71:2965-2974, 1993.

89. Diles JJB, Miller MF, Owen BL: Calcium chloride concentration, injection time, and aging period effects on tenderness, sensory, and retail color attributes of loin steaks from mature cows. J Anim Sci 72:2017-2021, 1994.

90. Farouk MM, Price JF: The effect of postexsanguination infusion on the composition, exudation, color and postmortem metabolic changes in lamb. Meat Sci 38:477-496, 1994.

91. Boleman SJ, Boleman SL, Bidner TD, et al: Effects of postmortem time of calcium chloride injection on beef tenderness and drip, cooking and total loss. Meat Sci 39:35-41, 1995.

92. Kerth CR, Miller MF, Ramsey CB: Improvement of beef tenderness and quality traits with calcium chloride injection in beef loins 48 hours postmortem. J Anim Sci 73:750-756, 1995.

93. Lansdell JL, Miller MF, Wheeler TL, et al: Postmortem injection of calcium chloride effects on beef quality traits. J Anim Sci 73:1735-1740, 1995.

94. Miller MF, Huffman KL, Gilbert SY, et al: Retail consumer acceptance of beef tenderized with calcium chloride. J Anim Sci 73:2308-2314, 1995.

95. Wheeler TL, Koohmaraie M, Shackelford SD: Effect of vitamin C concentration and co-injection with calcium chloride on beef retail display color. J Anim Sci 74:1846-1853, 1996.

96. Wulf DM, Morgan JB, Tatum JD, Smith GC: Effects of animal age, marbling score, calpastatin activity, subprimal cut, calcium injection, and degree of doneness on the palatability of steaks from Limousine steers. J Anim Sci 74:569-576, 1996.

97. Yancey EJ, Dikeman ME, Addis PB, et al: Effects of vascular infusion with a solution of saccharides, sodium chloride, and phosphates with or without vitamin C on carcass traits, Warner-Bratzler shear force, flavor-profile, and descriptive-attribute characteristics of steaks and ground beef from Charolais cattle. Meat Sci 60:341-347, 2002.

Recommended Reading

Ouali A: Proteolytic and physiochemical mechanisms involved in meat texture. Biochimie 74:251-265, 1992.




Table 1. Effect of Length of Postmortem Storage on Beef Shear Force Values (kg/cm2)



               7 days    14 days % > 6 kg/     Correlation % > 6 kg day 7
Breed       n aging mean aging range cm2  mean   range   /cm2 to day 14


Angus              102       5.11            2.57-9.30          22        4.05      2.48-9.04         5             0.58


Tuli                    158       5.71           2.94-12.38         34        4.58      2.33-9.24         8             0.65


Hereford           106       5.67           2.37-11.91         31        4.74      2.41-8.30        12            0.66


Belgian Blue     144       5.82           2.52-10.57         42        4.82      2.64-8.41        14            0.61


Boran               138       6.58           3.15-11.79         55        5.14     2.84-11.25       26            0.76


Brahman           119       7.30           3.43-12.50         63        6.05     2.66-11.03       34            0.80


All breeds         767       5.95           2.37-12.50         42        4.86     2.33-11.25       17            0.72

Source: Koohmaraie.4



TABLE 2. Changes in Skeletal Muscle During Postmortem Storage of Carcasses


Table 3. Experimental Evidence Showing the Role of Proteolysis in Postmortem Meat Tenderization


* Z-disk weakening and/or degradation, which leads to fragmentation of myofibrils

* Degradation of desmin, which leads to fragmentation of myofibril, probably through disruption of transverse crosslinking between myofibrils

* Degradation of titin; titin filaments connect myosin filaments, along their length, from the M-line to the Z-disk; therefore, degradation of titin during post mortem storage would cause weakening of myofibril strength and, consequently, improvement in meat tenderness

* Degradation of nebulin; because of the location of nebulin in myofibrils (I-band), it is not clear how nebulin degradation will affect meat tenderness

* Disappearance of troponin-T and simultaneous appearance of polypeptides with molecular weight 28-32 kDa; This is the most noticeable and reported change that occurs during postmortem storage

* Appearance of a polypeptide with molecular weight of 95 kDa; neither the origin nor its significance to meat tenderness is known

* Perhaps the most significant observation is that the major contractile proteins, myosin and actin, are not affected, even after 56 days of postmortem storage


Source: Koohmaraie.10 


* Incubating muscle slices with calcium chloride induces proteolysis of myofibrillar proteins and fragmentation of myofibrils; however, incubation of muscle slices with calcium chelators (EDTA and EGTA) prevents both degradation of myofibrillar proteins and myofibril fragmentation

* Infusion of carcasses with calcium chloride accelerates postmortem changes (degradation of myofibrillar proteins, tenderness) in skeletal muscle so that postmortem storage to ensure meat tenderness is no longer necessary

* Infusion of carcasses with zinc chloride inhibits all postmortem changes measured (degradation of myofibrillar proteins, myofibril fragmentation, tenderization)

* Muscle from b-adrenergic agonist (BAA)-fed lambs, which does not undergo postmortem proteolysis (no detectable degradation of myofibrillar proteins and myofibril fragmentation during postmortem storage), is tougher than muscle from untreated lambs. However, calcium chloride infusion of carcasses from BAA-fed lambs induces degradation of myofibrillar proteins and eliminates their meat toughness


Source: Koohmaraie.9



Table 4. General Properties of the Calpain System


Occurrence: found in all vertebrate cells that have been examined.

Ubiquitous Calpains

Name                      Polypeptides Ca2+- required for half  maximal activity

Calpain I (µ-calpain)                                 80, 28-kDa                                       3-50 µmol

Calpain II (m-calpain)                                80, 28-kDa                                    400-800 µmol

Tissue-specific calpains

Name                      Polypeptides               Tissue

skm-calpain, p94, calpain 3                      94, 82-kDa                            skeletal muscle, rat lens

n-calpain-2, nCL-2                                      80-kDa                                     stomach muscle

n-calpain-3, nCL-3                                      43-kDa                                     stomach muscle

All calpains that have been isolated in protein form are cysteine proteases with optimal pH of 7.2-8.2


Multiheaded protein inhibitor that inhibits only the calpains; expressed in several different isoforms that have one, three, or four inhibitory domains and different N-terminal sequences.

Cellular distribution

The calpains and calpastatins studied thus far are located exclusively intracellularly; various proportions of the calpains are associated with subcellular organelles, which are primarily myofibrils in skeletal muscle, but may include the plasma membrane, mitochondria, and nuclei.

Source: Goll et al.80



Table 5. Role of Calpain System in Postmortem Tenderization


* Very little degradation of myosin and actin occurs during postmortem storage at 2˚ to 4˚C for 72 h, even though most of the total postmortem tenderization occurs during that period

    1. The calpains are unique among the known proteolytic enzymes in that they do not degrade undenaturated myosin and actin

    2. The known cathepsins all degrade myosin and actin

* Very little degradation of a-actinin, the major protein in skeletal muscle Z-disks, occurs during postmortem storage at 2˚ to 4°C for 72 h

    1. Several of the cathepsins and many other proteases (ie, trypsin) degrade the Z-disk structure, and this degradation is accompanied by degradation of a-actinin; the calpains, however, are unique in that they degrade the Z-disk structure, but they release a-actinin from this structure without degrading it to small fragments

    2. Degradation of myosin, actin and a-actinin occurs during post mortem storage at 37˚C, and this degradation may be due to the cathepsins

* There is very little proteolysis of muscle proteins during post mortem storage at 2˚ to 4°C

    1. The sarcomere structure remains largely intact

    2. Functional actomyosin and a-actinin can be isolated from skeletal muscle even after 13 days of postmortem storage at 2˚ to 4˚C

* Several studies have shown that increasing Ca2+ concentration in muscle results in increased tenderness

* A number of studies have shown that tenderness increases to a greater extent during postmortem storage in those muscles that have higher calpain (especially calpain I) or lower calpastatin activities than in other muscles; low calpastatin activity especially seems highly associated with increased postmortem tenderization


Source: adapted from Taylor et al.45




Table 6. Ionic Compounds Injected During Postmortem Aging in Carcasses of Meat Animals


Species Animals, n Ionic compounds injected Study

Lambs              24              Calcium chloride                      Koohmaraie et al81

Lambs              20              Calcium chloride                      Koohmaraie et al82

Lambs              18              Sodium chloride                      Koohmaraie et al82

Lambs              24              Calcium chloride                      Koohmaraie et al65

Beef                 12              Calcium chloride                      Koohmaraie et al65

Lambs              12              Zinc chloride                           Koohmaraie83

Lambs              32              Calcium chloride                      Koohmaraie and Shackelford84

Beef                 10              Calcium chloride                      Morgan et al66

Lambs              25              Calcium chloride                      St. Angelo et al85

Beef                 90              Maltose, dextrose,                  Farouk et al86

                                           polyphosphate and glycerin

Beef                 25              Calcium chloride                      Wheeler et al87

Beef                 20              Calcium chloride                      Wheeler et al88

Beef                 10              Calcium chloride                      Diles et al89

Lambs              24              Maltose, dextrose,                  Farouk and Price90

                                           polyphosphate, glycerin

                                           plus calcium chloride

Beef                 12              Calcium chloride,                     Geesink et al36

                                           Sodium chloride,

                                           Zinc chloride

Beef                 16              Calcium chloride                      Boleman et al91

Beef                 12              Calcium chloride                      Kerth et al92

Beef                 22              Calcium chloride                      Lansdell et al93

Beef                 22              Calcium chloride                      Miller et al94

Beef                 20              Calcium chloride                      Wheeler et al95

Beef                114             Calcium chloride                      Wulf et al96

Beef                 20              Calcium chloride                      Wheeler et al74

Beef                 12              Sodium pyrophosphate           Lee et al37
                                           plus sodium chloride              

Lambs              36              Calcium chloride                      Polidori et al38

Beef                 48              Calcium chloride                      Polidori et al75

Beef                 36              NaCl and phosphates             Yancey et al97

Pork                 36              Calcium chloride                      Rees et al77

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