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Lipids in argentine beef cuts |
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| P. T. GARCIA and
A. CASTRO ALMEYRA Instituto de Tecnologia de Carnes, CICV, INTA. CC 77, 1708 Moron, Buenos Aires, Argentina. |
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Summary
The intramuscular fat (IMF%), total cholesterol and the fatty acid composition were determined in twelve cuts from forty grass-fed Angus steers, selected at random from a commercial exploitation, at two carcass fat levels. The IMF% were from 1 to 4.6 in Fat 1 and from 1.1 to 5.4 in Fat 2. The average CV% were 30+-5.7 in Fat 1 and 34 +- 9.4 in Fat 2. The cholesterol contents were between 46.3 and 58.9 mg% in Fat 1 and 47.7 to 60.3 mg% in Fat 2. The fatty acid composition was strongly affected by the IMF% Introduction The lipid content of beef, is a very important aspect for Argentine, considering the importance of the country as beef exporter and beef consumer (approximately 80,& kg/person/year). Beef is considered a food with high levels of saturated fat and cholesterol. The consumption of saturated fatty acids has been shown to increase plasma LDL-cholesterol in man (Mattson and Grundy, 1985) and the increase of LDL-cholesterol has been correlated with coronary heart disease. Consumers are becoming more diet/health conscious, and it is of considerable importance to the meat industry to produce red meat that is perceived as being more healthful. Investigations have been performed which show that beef produces on grass has less intramuscular fat than beef supplemented with grains (Marmer et al., 1984). Feeley et al. (1972) have shown beef to be similar to, or lower than, other meats in cholesterol concentration. The objective of this paper is report the amounts of intramuscular fat, the fatty acid composition and the cholesterol content of 12 commercial beef cuts from 40 grass fed Angus steers representing two different carcass fat levels. Materials and Methods Forty grass fed Angus steers were selected at random from a commercial exploitation (Cabaña Las Lilas. Comega S.A.), 20 steers classified as Fat 1 and 20 steers as Fat 2 according to the Argentine Meat Board standard regulations. The steers were of similar birth date, live-weight at slaughter and management. The average half carcass weight was 107 kg. The selected cuts, Adductor externus (A), Biceps femoris (BF), Gluteos superficialis et medious (G), Infraspinatus (I), Loncissimus (LD 10-12th and LD 5-6th ribs), Psoas major (P), Rectus femoris (RF), Semimembranosus (SM), Semitendinosus (ST), the lean part were finely chopped. Aliquot samples of 10 g were extracted to determine the total weight of chemical fat according to the Official Method of the British Standards Institution (1958). Fatty acid composition and cholesterol were determined in aliquot samples from the chloroform lipid extract obtained according to Folch et al. (1957). The methylesteres were analyzed using GLC (Garcia et al., 1979) and cholesterol with an enzymatic-colorimetric method ( Roschlan et al., 1975). The data were analyzed with the SYSTAT 1987 Statistical Program. Results and Discusion The intramuscular fat content (IMF%) of the 12 muscles from Fat 1 and Fat 2 steers are given in Fig.l. The CV (%) are presented in Fig. 2. The IMF% are lower than the ones given by The National Research Council (1988) for several USA beef cuts and grades. Marmer et al. (1984) have demonstrated that tissues from grass fed steers are leaner than tissue from grain fed steers. The fatty acid composition from a very lean muscle as BF and one of the fattiest as PM is shown in Fig.3. The fatty acid composition for the other muscles showed intermediates values according to the IMF%. In Table 1 are given the percentages of saturated, monounsaturated, polyunsaturated, n-6, n-3 fatty acid and other relations for the Mm BF and PM. The changes in the fatty acid composition of intramuscular lipids are related to the relative changes in concentration among the lipids classes. The mg of cholesterol % g of muscle in the two fat levels are presented in Fig. 3. The SD values are given in Fig. 4. The values were similar to the given in the literature for lean beef ( Rhee et al., 1982). In Fig. 5 de SD are presented. The relation between cholesterol content and IMF% was not statistically significant (Fig. 6) but a slight increment in cholesterol with increasing amounts of IMF% was detected. Rhee el al. (1982) found no significant differences in cholesterol content ( wet wt. basis) among steaks with different amounts of marbling except that steaks with "Practicaly Devoid" marbling. When cholesterol content was calculated on a lipid-content basis (mg/100g lipid) a negative relation was found between amounts of IMF and cholesterol content (mg/100g lipid). The correlation coefficient for the different beef cuts were SM (0.79), BF (0.53), ST (0.70), LD10-12th (0.99), G (0.87), TFL (0.84), LD 5-6th (0.91), I (0.63), RF (0.79), A (0.66), SS (0.92) and P (0.97) (p < .05). Conclusions The variability in the percentages of intramuscular fat among the different beef cuts allows the selection of cuts with very low levels of fat. The cholesterol content is not significantly affected by the intramuscular fat content. The fatty acid composition is strongly affected by the intramuscular content. Table 1. Percentages of saturated (SFA), monounsaturated (MUFA) and polyunsaturated (PUFA) fatty acid in the lipids from Mm BF and PM.
References Animal Product Options in the Marketplace. In "Designing Foods". National Research Council USA. 1988. FEELEY R. M., CRINER P. E. and WATT B. K., 1972. Cholesterol content of food. J. Amer. Diet. Assoc. 61,134-139. FOLCH J., LEES M. and SLOANE G. H. S., 1957. A simple method for the isolation and purification of total lipids from animal tissues. J. Biol. Chem. 226,497-509. GARCIA P. T., CASAL J.J., PARODI J. J. and MARANGUNICH L., 1979. Effects of body fat. distribution on the fatty acid composition of the depot fat of cattle. meat Sci. 169-177. HARMER W. H., MAXWELL R. J. and WILLIAMS J. E., 1984. Effects of dietary regimen and tissue site on bovine fatty acid profiles. J. Anim. Sci. 59,109-121. MATTSON F. H. and GRUNDY S. H., 1985. Comparison of effects of dietary saturated, monounsaturated fatty acid on plasma lipids and lipoproteins in man. J. Lipid. Res. 26,194202. RHEE S. K., DUTSON T. R. and SMITH G. C., 1982. Effect of changes in intermuscular and subcutaneous fat levels on cholesterol content of raw and cooked beef steaks. J. Food Sci. 47. 1638-1642. ROSCHLAN P. BERNARD E. and GRUBER W., 1975. (th Int. Congress on Clin. Chem. Toronto. Abstr. No 1. |
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