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Food, fibre and pharmaceuticals from animals
RESEARCH ARTICLE

Effects of stimulation on tenderness of lamb with a focus on protein degradation

K. M. Martin A B E , D. L. Hopkins A C , G. E. Gardner A D and J. M. Thompson A B

A Australian Sheep Industry Cooperative Research Centre, Chiswick, New England Highway, Armidale, NSW 2350, Australia.

B School of Rural Sciences and Natural Resources, University of New England, Armidale, NSW 2351, Australia.

C NSW Department of Primary Industries, Centre for Sheep Meat Development, Cowra, NSW 2794, Australia.

D School of Veterinary and Biomedical Sciences, Murdoch University, Murdoch, WA 6150, Australia.

E Corresponding author. Email: kirstie.martin@une.edu.au

Australian Journal of Experimental Agriculture 46(7) 891-896 http://dx.doi.org/10.1071/EA06010
Submitted: 26 November 2005  Accepted: 8 May 2006   Published: 8 June 2006

Abstract

Past studies have identified that electrical stimulation systems not only affect the pH–temperature decline of lamb carcasses, but also affect the tenderness of the product. It is unknown whether these differences are due to the effects of an optimal pH–temperature decline path by which the occurrence of shortening is decreased and proteolytic enzyme activity is increased, or by another mechanism, such as disruption of the muscle myofibres. This study attempted to elucidate this by placing control and mid-voltage electrically stimulated samples of the M. longissimus thoracis et lumborum in a water bath to prevent shortening by imposing an even pH–temperature decline on all samples. In order to obtain a complete understanding of the effects of stimulation on the muscle, samples were taken for indicators of tenderness, myofibre degradation and protein breakdown. No effect of stimulation was seen on tenderness and structural degradation measures aside from the expected rapid lowering of muscle pH. Interesting relationships were observed, however, between the different methods of meat tenderness assessment, with muscle structural protein degradation, shear force and muscle fibre and myofibre breakdown comparisons. These results suggest that the effects of electrical stimulation seen in mid-voltage systems as applied in this study are due only to the prevention of shortening conditions.

Additional keywords: fibre breaks, lamb, myofibrillar protein, tenderness.


References

Anon. (1992) ‘AUS-MEAT language.’ 4th edn. (Authority for Uniform Specification Meat and Livestock: Sydney)

Banks RG (1994) LAMBPLAN: genetic evaluation for the Australian lamb industry. In ‘Proceedings of the 5th world congress on genetics applied to livestock production’. pp. 15–18.

Devine CE , Lowe TE , Wells RW , Edwards NJ , Hocking Edwards JE , Starbuck TJ , Speck PA (2002 a) The effect of preslaughter stress and electrical stimulation on meat tenderness. In ‘Proceedings 48th international congress of meat science and technology’. pp. 218–219.

Devine CE Payne SR Peachey BM Lowe TE Ingram JR Cook CJ 2002 b High and low rigor temperature effects on sheep meat tenderness and ageing. Meat Science 60 141 146 doi:10.1016/S0309-1740(01)00115-2

Devine CE , Hopkins DL , Hwang IH , Ferguson DM , Richards I (2004) Electrical stimulation. In ‘Encyclopaedia of meat sciences’. (Eds W Jensen, C Devine, M Dikeman) pp. 413–423. (Oxford: Elsevier)

Hopkins DL Thompson JM 2001 a The relationship between tenderness, proteolysis, muscle contraction and dissociation of actomyosin. Meat Science 57 1 12 doi:10.1016/S0309-1740(00)00065-6

Hopkins DL Thompson JM 2001 b Inhibition of protease activity. 2. Degradation of myofibrillar proteins, myofibril examination and determination of free calcium levels. Meat Science 59 199 209 doi:10.1016/S0309-1740(01)00071-7

Hopkins DL Martin L Gilmour AR 2004 The impact of homogenizer type and speed on the determination of myofibrillar fragmentation. Meat Science 67 705 710 doi:10.1016/j.meatsci.2004.01.011

Hopkins DL Shaw FD Baud S Walker PJ 2005 Effects of level of current during lamb carcase electrical stimulation on post-mortem muscle changes and meat quality. Proceedings of the New Zealand Society of Animal Production 65 247 251

Hwang IH Devine CE Hopkins DL 2003 The biochemical and physical effects of electrical stimulation on beef and sheep meat tenderness – a review. Meat Science 65 677 691
doi:10.1016/S0309-1740(02)00271-1

Lametsch R Roepstorff P Møller HS Bendixen E 2004 Identification of myofibrillar substrates for μ-calpain. Meat Science 68 515 521 doi:10.1016/j.meatsci.2004.03.018

Lee S Polidori P Kauffman RG Kim BC 2000 Low-voltage electrical stimulation effects on proteolysis and lamb tenderness. Journal of Food Science: Food Chemistry and Toxicology 10 786 790

Martin LC Hopkins DL Morgan JE 2004 Streamlining the determination of myofibrillar fragmentation index. Animal Production in Australia 25 279


Morton JD Bickerstaffe R Kent MP Dransfield E Keeley GM 1999 Calpain-calpastatin and toughness in M. longissimus from electrically stimulated lamb and beef carcasses. Meat Science 52 71 79
doi:10.1016/S0309-1740(98)00150-8

Pearce KL Hopkins DL Toohey ES Pethick DW Richards I 2006 Quantifying the rate of pH and temperature decline in lamb carcasses using medium voltage electrical stimulation in an Australian abattoir. Australian Journal of Experimental Agriculture 46 869 874

Steen D Claeys E Uytterhaegen L De Smet D Demeyer D 1997 Early post-mortem conditions and the calpain/calpastatin system in relation to tenderness of double-muscled beef. Meat Science 45 307 319
doi:10.1016/S0309-1740(96)00124-6

Taylor RG , Frylinck L (2003) Muscle structures which determine meat tenderness in South African and other beef breeds. In ‘Proceedings of the 11th international meat symposium’. pp. 23–27.

Toohey ES Hopkins DL 2004 Preliminary data on the rate of glycolysis in ovine carcasses under commercial processing. Animal Production in Australia 25 330


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