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Composition of minced meat part B: A survey of commercial ground meat
Meat Science 38 (1994) 503-509
© 1994 Elsevier Science Limited Printed in Great Britain. All rights reserved 0309-1740/94/$07.00 ELSEVIER
Composition of Minced Meat Part B: A Survey of Commercial Ground Meat Anneli Skr/Skki Food and Water Research Institute of Kajaani, Tehdaskatu 1, SF-87100 Kajaani, Finland
& Osmo Hormi University of Oulu, Department of Chemistry, Linnanmaa, SF-90570 Oulu, Finland (Received 21 February 1992; revised versions received 5 July 1992, 1 October 1993; accepted 14 November 1993)
A B S T R A CT A modified polyacrylamide-gel electrophoretic method was used to differentiate qualitatively various species of meat such as beef, pork, venison, reindeer, and mutton. The composition of commercial minced meat was examined;and illegal adulterations of minced beef with pork were detected
INTRODUCTION Meat has been examined by polyacrylamide-gel electrophoresis by many investigators (Payne, 1963; Mackie, 1969; Thornson et al., 1969; Hofman & Penny, 1971, 1973; Hofman, 1973; Hay et al., 1973; Ramdas & Misra, 1974; Young & Lawrie, 1975; Hamn et al., 1979; Caldironi & Bazan, 1980; Babiker et aL, 1980-81; Ring et al., 1982; Koohmaraie et al., 1984a, b) and also immunochemically (Hayden, 1978; Swart & Wilks, 1982). A survey of immunochemical techniques has been made by Patterson (1985). Electrophoresis on polyacrylamide gels gives characteristic protein patterns for the different meats, e.g. beef, pork, mutton, venison, and reindeer. Disc electrophoretograms are a good tool for differentiating between the meats of various animal species and also allow the possible quantitative determination of beef and pork. In this survey, muscle extracts from beef, pork, venison, reindeer, mutton, and a mixture of these meats were examined electrophoretically; the amounts of beef and pork in commercial minced-meat mixtures were also determined quantitatively by reference to standard electrophoretograms. This enabled the extent of meat adulteration to be examined. 503
504
Anneli SkrOkkL Osmo Hormi
MATERIALS AND METHODS All the minced-meat samples collected from different shops were homogenized and the proteins extracted into water. The supernatant solutions were preserved in a frozen state until analysed. The standard materials used were minced, homogenized beef, pork, venison, reindeer meat, and mutton, which were all handled in the same manner. The species compositions of the samples were determined by polyacrylamide-gel electrophoresis according to a modified method of Mackie (1969) and as described by us in Part A of this series. RESULTS AND DISCUSSION
Qualitative determination Different meat species, such as beef, pork, venison, reindeer meat, and mutton, can be identified by polyacrylamide-gel electrophoresis. The meat proteins of the extracts were separated with the aid of a constant potential of 280-300 V and suitable run time (1 h 30 min-2 h 15 min). The characteristic differences between the animal proteins analysed can be seen in the photograph in Fig. 1. Since all the proteins originated from animals, the variations between the electrophoretograms are not great, but variations exist, which makes qualitative determination from pure-protein mixtures possible. It is especially easy to identify pork, venison, and reindeer from the same meat mixture by this technique but the main bands for beef, reindeer, and mutton are similar, as can be seen in Fig. 2, so that it is a little more difficult to differentiate between the electrophoretograms of proteins obtained from beef and mutton. Separation is possible when the run time is long enough, however. The ideal run time depends on the electrophoretic system used.
Survey of commercial ground meat Minced beef or a mixture of beef and pork is sold directly in shops in Finland, and sometimes minced beef may contain a small amount of pork, which is iller gal. Furthermore, the amounts of beef and pork in the minced meat can vary, quite legally. Thus we were interested to see what the composition of minced meat sold in shops really was. A set of 49 minced-beef and 49 minced-beef-and-pork samples was analysed by polyacrylamide gel electrophoresis, and the resulting electrophoretograms were compared visually with standard ones obtained in the same manner (potential 280 V, run time 1 h 30 min, amount of sample 30/xl). The standard electrophoretograms are presented in Figs 3-6. The standard beef-pork mixtures used contained 5, 10. . . . 100% beef by weight. The results of our meat-species examinations are presented in Table 1, in which it can be seen that five minced-beef samples, about 10% of the beef samples examined, contained 5-20% pork, usually about 5%. No other meat, such as venison or reindeer, was detected. The results of minced-beef and pork usually contained 70% beef and 30% pork, but other proportions are possible.
Composition of minced meat: survey of commercial ground meat
505
Fig. 1. Eleetrophoretograms of different meats (potential 280 V, run time 2 h 30 min, sample amount 40 ~1). The meat order from left to right is pork, beef, venison, reindeer, mutton, and sample.
Fig. 2. Eleetrophoretograms of different meats (potential 250 V, run time 4 h, sample amount 40/.d). The meat order from left to right is pork, beef, venison, reindeer, mutton, and a mixture of all five types.
506
Anneli Skr6kki, Osmo Hormi
Fig. 3. Electrophoretograms of standards (potential 280 V, run time 1 h 30 min, sample amount 30/zl). The order from left to right is beef, 95% beef and 5% pork, 90% beef and 10°/0 pork, 85% beef and 15% pork, 80% beef and 20% pork, pork.
Fig. 4. Electrophoretograms of standards (potential 280 V, run time 1 h 30 min, sample amount 30/zl). The order from left to right is beef, 75% beef and 25% pork, 70% beef and 30% pork, 65% beef and 35% pork, 60% beef and 40% pork, pork.
Composition of minced meat: survey of commercial ground meat
507
Fig. 5. Electrophoretograms of standards (potential 280 V, run time 1 h 30 min, sample amount 30/zl). The order from left to right is beef, 55% beef and 45% pork, 50% beef and 50% pork, 45% beef and 55% pork, 40% beef and 60% pork, pork.
Fig. 6. Electrophoretograms of standards (potential 280 V, run time 1 h 30 min, sample amount 30/zl). The order from left to right is beef, 30% beef and 70% pork, 20% beef and 80% pork, 10% beef and 90% pork, beef, pork.
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Composition of minced meat: survey of commercial ground meat
509
Thus commercial minced meat can be identified qualitatively by this method and the amounts o f beef and pork can be determined quantitatively. The method is quick, cheap, and reliable and allows a large number o f samples to be processed in a single gel. N o expensive instruments are needed for testing the composition of commercial minced meat. ACKNOWLEDGEMENT We are grateful to the Association o f Finnish Chemical Societies for financial support and to Mr Malcolm Hicks for checking the English o f this paper. REFERENCES Babiker, S. A., Glover, P. A. & Lawrie, R. A. (1980-81). Meat Sci., 5, 473. Caldironi, H. A. & Bazan, N. G. (1980). J. Food Sci., 45, 901. Hamn, R., R6ssler, I. & Hofmann, K. (1979). Fleischwirtsch, 59, 989. Hay, J. D., Currie, R. W. & Wolfe, F. H. (1973). J. Food Sci., 38, 987. Hayden, A. R. (1978). J. Food Sci., 43, 476. Hofman, K. (1973). Fresenius's Z. Anal, Chem., 267, 355. Hofman, K. & Penny, I. F. (1971). Fleischwirtschaft, 51, 577. Hofman, K. & Penny, I. F. (1973). Fleischwirtschaft, 53, 252. Koohmaraie, M., Kennick, W. H., Amglemier, A. F., Elgasirn, E. A. & Jones, T. K. (1984). J. Food Sci., 49, 290. Koohmaraie, M., Kennick, W. H., Elgasim, A. E. & Amglemier, A. F. (1984). J. Food Sci., 49, 292. Mackie, I. M. (1969). J. Assoc. Publ. Anal., 7, 83. Patterson, R. L. S. (Editor) (1985). Biochemical Identification of Meat Species. Elsevier Applied Science, London. Payne, W. R. (1963). J.A.O.A.C., 46, 1003. Ramdass, P. & Misra, D. S. (1974). Indian J. Anim. ScL, 44, 844. Ring, C., Weigert, P. & Hellmannsberger, L. (1982). Fleischwirtschaft, 62, 648. Swart, K. S. and Wilks, C. V. (1982). Aut. Vet. J., 59, 21. Thomson, B., Skaare, K. & H6em, T. (1969). Nord. Vet. Med., 21,436. Young, R. H. & Lawrie, R. A. (1975). J. Food Technol., 10, 523.
© 1994 Elsevier Science Limited Printed in Great Britain. All rights reserved 0309-1740/94/$07.00 ELSEVIER
Composition of Minced Meat Part B: A Survey of Commercial Ground Meat Anneli Skr/Skki Food and Water Research Institute of Kajaani, Tehdaskatu 1, SF-87100 Kajaani, Finland
& Osmo Hormi University of Oulu, Department of Chemistry, Linnanmaa, SF-90570 Oulu, Finland (Received 21 February 1992; revised versions received 5 July 1992, 1 October 1993; accepted 14 November 1993)
A B S T R A CT A modified polyacrylamide-gel electrophoretic method was used to differentiate qualitatively various species of meat such as beef, pork, venison, reindeer, and mutton. The composition of commercial minced meat was examined;and illegal adulterations of minced beef with pork were detected
INTRODUCTION Meat has been examined by polyacrylamide-gel electrophoresis by many investigators (Payne, 1963; Mackie, 1969; Thornson et al., 1969; Hofman & Penny, 1971, 1973; Hofman, 1973; Hay et al., 1973; Ramdas & Misra, 1974; Young & Lawrie, 1975; Hamn et al., 1979; Caldironi & Bazan, 1980; Babiker et aL, 1980-81; Ring et al., 1982; Koohmaraie et al., 1984a, b) and also immunochemically (Hayden, 1978; Swart & Wilks, 1982). A survey of immunochemical techniques has been made by Patterson (1985). Electrophoresis on polyacrylamide gels gives characteristic protein patterns for the different meats, e.g. beef, pork, mutton, venison, and reindeer. Disc electrophoretograms are a good tool for differentiating between the meats of various animal species and also allow the possible quantitative determination of beef and pork. In this survey, muscle extracts from beef, pork, venison, reindeer, mutton, and a mixture of these meats were examined electrophoretically; the amounts of beef and pork in commercial minced-meat mixtures were also determined quantitatively by reference to standard electrophoretograms. This enabled the extent of meat adulteration to be examined. 503
504
Anneli SkrOkkL Osmo Hormi
MATERIALS AND METHODS All the minced-meat samples collected from different shops were homogenized and the proteins extracted into water. The supernatant solutions were preserved in a frozen state until analysed. The standard materials used were minced, homogenized beef, pork, venison, reindeer meat, and mutton, which were all handled in the same manner. The species compositions of the samples were determined by polyacrylamide-gel electrophoresis according to a modified method of Mackie (1969) and as described by us in Part A of this series. RESULTS AND DISCUSSION
Qualitative determination Different meat species, such as beef, pork, venison, reindeer meat, and mutton, can be identified by polyacrylamide-gel electrophoresis. The meat proteins of the extracts were separated with the aid of a constant potential of 280-300 V and suitable run time (1 h 30 min-2 h 15 min). The characteristic differences between the animal proteins analysed can be seen in the photograph in Fig. 1. Since all the proteins originated from animals, the variations between the electrophoretograms are not great, but variations exist, which makes qualitative determination from pure-protein mixtures possible. It is especially easy to identify pork, venison, and reindeer from the same meat mixture by this technique but the main bands for beef, reindeer, and mutton are similar, as can be seen in Fig. 2, so that it is a little more difficult to differentiate between the electrophoretograms of proteins obtained from beef and mutton. Separation is possible when the run time is long enough, however. The ideal run time depends on the electrophoretic system used.
Survey of commercial ground meat Minced beef or a mixture of beef and pork is sold directly in shops in Finland, and sometimes minced beef may contain a small amount of pork, which is iller gal. Furthermore, the amounts of beef and pork in the minced meat can vary, quite legally. Thus we were interested to see what the composition of minced meat sold in shops really was. A set of 49 minced-beef and 49 minced-beef-and-pork samples was analysed by polyacrylamide gel electrophoresis, and the resulting electrophoretograms were compared visually with standard ones obtained in the same manner (potential 280 V, run time 1 h 30 min, amount of sample 30/xl). The standard electrophoretograms are presented in Figs 3-6. The standard beef-pork mixtures used contained 5, 10. . . . 100% beef by weight. The results of our meat-species examinations are presented in Table 1, in which it can be seen that five minced-beef samples, about 10% of the beef samples examined, contained 5-20% pork, usually about 5%. No other meat, such as venison or reindeer, was detected. The results of minced-beef and pork usually contained 70% beef and 30% pork, but other proportions are possible.
Composition of minced meat: survey of commercial ground meat
505
Fig. 1. Eleetrophoretograms of different meats (potential 280 V, run time 2 h 30 min, sample amount 40 ~1). The meat order from left to right is pork, beef, venison, reindeer, mutton, and sample.
Fig. 2. Eleetrophoretograms of different meats (potential 250 V, run time 4 h, sample amount 40/.d). The meat order from left to right is pork, beef, venison, reindeer, mutton, and a mixture of all five types.
506
Anneli Skr6kki, Osmo Hormi
Fig. 3. Electrophoretograms of standards (potential 280 V, run time 1 h 30 min, sample amount 30/zl). The order from left to right is beef, 95% beef and 5% pork, 90% beef and 10°/0 pork, 85% beef and 15% pork, 80% beef and 20% pork, pork.
Fig. 4. Electrophoretograms of standards (potential 280 V, run time 1 h 30 min, sample amount 30/zl). The order from left to right is beef, 75% beef and 25% pork, 70% beef and 30% pork, 65% beef and 35% pork, 60% beef and 40% pork, pork.
Composition of minced meat: survey of commercial ground meat
507
Fig. 5. Electrophoretograms of standards (potential 280 V, run time 1 h 30 min, sample amount 30/zl). The order from left to right is beef, 55% beef and 45% pork, 50% beef and 50% pork, 45% beef and 55% pork, 40% beef and 60% pork, pork.
Fig. 6. Electrophoretograms of standards (potential 280 V, run time 1 h 30 min, sample amount 30/zl). The order from left to right is beef, 30% beef and 70% pork, 20% beef and 80% pork, 10% beef and 90% pork, beef, pork.
c~
~D
Z
~ ~ - ~ o o o o o o o o o ~~
..
~ o o o ~ ~
.............
~---~
0 C~
C~
c~
~-
O0
Composition of minced meat: survey of commercial ground meat
509
Thus commercial minced meat can be identified qualitatively by this method and the amounts o f beef and pork can be determined quantitatively. The method is quick, cheap, and reliable and allows a large number o f samples to be processed in a single gel. N o expensive instruments are needed for testing the composition of commercial minced meat. ACKNOWLEDGEMENT We are grateful to the Association o f Finnish Chemical Societies for financial support and to Mr Malcolm Hicks for checking the English o f this paper. REFERENCES Babiker, S. A., Glover, P. A. & Lawrie, R. A. (1980-81). Meat Sci., 5, 473. Caldironi, H. A. & Bazan, N. G. (1980). J. Food Sci., 45, 901. Hamn, R., R6ssler, I. & Hofmann, K. (1979). Fleischwirtsch, 59, 989. Hay, J. D., Currie, R. W. & Wolfe, F. H. (1973). J. Food Sci., 38, 987. Hayden, A. R. (1978). J. Food Sci., 43, 476. Hofman, K. (1973). Fresenius's Z. Anal, Chem., 267, 355. Hofman, K. & Penny, I. F. (1971). Fleischwirtschaft, 51, 577. Hofman, K. & Penny, I. F. (1973). Fleischwirtschaft, 53, 252. Koohmaraie, M., Kennick, W. H., Amglemier, A. F., Elgasirn, E. A. & Jones, T. K. (1984). J. Food Sci., 49, 290. Koohmaraie, M., Kennick, W. H., Elgasim, A. E. & Amglemier, A. F. (1984). J. Food Sci., 49, 292. Mackie, I. M. (1969). J. Assoc. Publ. Anal., 7, 83. Patterson, R. L. S. (Editor) (1985). Biochemical Identification of Meat Species. Elsevier Applied Science, London. Payne, W. R. (1963). J.A.O.A.C., 46, 1003. Ramdass, P. & Misra, D. S. (1974). Indian J. Anim. ScL, 44, 844. Ring, C., Weigert, P. & Hellmannsberger, L. (1982). Fleischwirtschaft, 62, 648. Swart, K. S. and Wilks, C. V. (1982). Aut. Vet. J., 59, 21. Thomson, B., Skaare, K. & H6em, T. (1969). Nord. Vet. Med., 21,436. Young, R. H. & Lawrie, R. A. (1975). J. Food Technol., 10, 523.