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Effect of Cooking on the Fatty Acid Composition of Beef Intramuscular Lipid
JOURNAL OF FOOD COMPOSITION AND ANALYSIS ARTICLE NO.
11, 357–362 (1998)
FC980600
Effect of Cooking on the Fatty Acid Composition of Beef Intramuscular Lipid1 S. K. Duckett2 and D. G. Wagner Department of Animal Science, Oklahoma State University, Stillwater, Oklahoma 74078, U.S.A. Received May 19, 1998, and in revised form September 10, 1998 Changes in fatty acid composition of neutral, polar and total lipid fractions of beef intramuscular lipid were assessed due to cooking. The longissimus muscle from 48 ribeye steaks was sectioned as: medial half for raw analysis (RAW) and lateral half for cooked analysis (COOK). Cooking reduced the percentages of oleic, linoleic, and linolenic acids and increased the percentage of stearic acid. These changes were most evident in the polar lipid fraction, where the unsaturated fatty acids occurred in the highest percentages. Overall, cooking increased the stearic acid and total saturated fatty acid contents of the intramuscular lipid while reducing total PUFA content. © 1998 Academic Press
INTRODUCTION The initial reports (Ahrens et al., 1957; Hegsted et al., 1965; Keys et al., 1965) of the relationship between dietary saturated fat intake and serum cholesterol levels has prompted concerns over the inclusion of beef products into a healthy diet. The intramuscular lipid of beefsteak contains over 50% of its fatty acids as unsaturated fatty acids (Duckett et al., 1993). Limited research is available to document changes in fatty acid composition with cooking. Harris et al. (1992) and Smith et al. (1989) found that cooking had little effect on the fatty acid composition of beef muscle total lipid extracts. However, fatty acid composition differs between lipid fractions (neutral lipid, storage fraction vs. polar lipid, membrane fraction) with the polyunsaturated fatty acids located primarily in the polar lipid (Sweeten et al., 1990; Duckett et al., 1993). Terrell et al. (1968) reported that cooking has a greater effect on the phospholipid (polar) fraction than the neutral lipid fraction. Thus, changes in fatty acid composition that occur during cooking may be overlooked when only total lipid extracts are analyzed. The objective of this study was to assess changes in fatty acid composition of the neutral lipid (NL), polar lipid (PL), and total lipid (TL) with cooking. MATERIALS AND METHODS Samples Forty-eight beef ribeye steaks (2.5 cm thick) were trimmed of all external fat and epimysial connective tissue. The steaks were then sectioned as: medial half for raw analysis (RAW) and lateral half for cooked analysis (COOK). The RAW steak was immediately pulverized in liquid nitrogen and stored at 220°C. The COOK steaks were 1
Approved for publication by the Director, Oklahoma Agricultural Experiment Station. To whom reprint requests should be addressed at current address: 216 Ag Science Bldg., University of Idaho, Moscow, ID 83844-2330. Fax: (208) 885-6420. E-mail: [email protected]. 2
357
0889-1575/98 $25.00 Copyright © 1998 by Academic Press All rights of reproduction in any form reserved.
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broiled on Farberware (Model 450A, Walter Kidde and Co., Bronx, NY) Open Hearth Broilers to an internal temperature of 70°C, as monitored by an Omega (Model OM 302-10) temperature logger equipped with copper constantan thermocouples. After cooling to room temperature, the COOK steaks were immediately pulverized in liquid nitrogen and stored at 220°C. Fatty Acids Samples were extracted using the dry column method (Marmer and Maxwell, 1981), which allows for the sequential elution of NL and PL. The NL (Slover and Lanza, 1979) and PL (Maxwell and Marmer, 1983) fractions were esterified to yield fatty acid methyl esters (FAME). The FAME were analyzed using a HP5890A gas chromatograph equipped with a flame-ionization detector and HP7673A automatic sampler (Hewlett–Packard Co., San Fernando, CA). Separations were accomplished on a 60-m SP2340 (Supelco, Bellefonte, PA) capillary column with a 0.25-mm internal diameter and 0.2-mm film thickness. The injector and detector were maintained at 280°C. Column oven temperature was programmed at 155–165°C at 0.5°C/min, 165–167°C at 0.2°C/min, and 167–200°C at 1.5°C/min and held at 200°C for 18 min. Data were collected and integrated by HP3365 ChemStation software (Hewlett–Packard Co.). Identification of fatty acids was based on retention times of reference compounds from Alltech (Alltech Associates, Deerfield, IL). Fatty acids were quantified by using an internal standard, methyl heneicosanoic acid (C21:0; Alltech Associates). Total lipid fatty acid profiles were calculated by multiplying the percentages of NL and PL in TL by each fatty acid. Statistical Analysis Paired t tests were used to analyze differences between the raw and cooked data. A significance level of P , .05 was used for all mean differences. RESULTS In the NL (Table 1), cooking reduced (P , .05) the percentage of palmitic (C16:0) acid and increased the percentage of stearic (C18:0) acid. Myristic (C14:0) acid was unchanged (P . .05) with cooking. These changes resulted in a 4% increase (P , .05) in the percentage of total saturated fatty acids (SFA) in the NL with cooking. The monounsaturated fatty acid (MUFA) content was reduced (P , .05) 5% after cooking due to a reduction (P , .05) in the oleic (C18:1) acid percentage. Palmitoleic (C16:1) acid was unchanged (P . .05) with cooking. The percentage of linoleic (C18:2) and arachidonic (C20:4) acids and the total polyunsaturated fatty acid (PUFA) content increased (P , .05) in the NL after cooking. Linolenic (C18:3) acid was not detected in the NL fraction. The percentage of unidentified fatty acids was higher (P , .05) in RAW than COOK. In the PL (Table 2), the percentage of myristic (C14:0) and stearic (C18:0) acids increased with cooking, whereas palmitic (C16:0) acid decreased in percentage. These changes resulted in a higher (P , .05) total SFA content for COOK steaks. The total MUFA content and the percentages of palmitoleic (C16:1) and oleic (C18:1) acids were unchanged (P . .05) with cooking. Linoleic (C18:2) and linolenic (C18:3) acids were reduced (P , .05) in percentage after cooking. Conversely, the percentage of arachidonic (C20:4) acid was increased in the cooked sample. The percentage of unidentified fatty
FATTY ACID COMPOSITION AFTER COOKING
359
TABLE 1 Fatty Acid Composition (%) of the Neutral Lipid before (RAW) and after Cooking (COOK)
Means for RAW and COOK differ (P , .05). SFA, saturated fatty acids (C14:0 1 C16:0 1 C18:0); MUFA, monounsaturated fatty acids (C16:1 1 C18:1); PUFA, polyunsaturated fatty acids (C18:2 1 C20:4). ab c
acids was higher (P , .05) in RAW than COOK. Overall, the total PUFA content of the PL was about 6% lower (P , .05) after cooking. In the TL (Table 3), the percentage of stearic (C18:0) acid and the total SFA content were increased (P , .05) 20 and 7% with cooking. Percentages of myristic (C14:0), palmitic (C16:0), palmitoleic (C16:1), and oleic (C18:1) acids and MUFA were unchanged (P . .05) with cooking in the TL. Cooking reduced (P , .05) the percentage of linoleic (C18:2), linolenic (C18:3), and arachidonic (C20:4) acids. The percentage of unidentified fatty acids was higher (P , .05) in RAW than COOK. The total PUFA content was about 29% lower (P , .05) after cooking. These changes in individual fatty acid percentage with cooking translated to differences in the amount (g/serving) of hypercholesterolemic fat (C14:0 1 C16:0), stearic (C18:0) acid, MUFA, and PUFA (Fig. 1). Intramuscular lipid retention was 99% during cooking and cooking shrink was 34.5%. Consumption of a 85.5-g (3 oz) serving of cooked beef ribeye steak would provide 2.4 g or about 13% of total calories as hypercholesterolemic (C14:0 1 C16:0) fat. DISCUSSION Cooking lean beefsteak with no external fat trim resulted in changes in the fatty acid composition between the lipid fractions. The neutral lipid fraction represents the storage component of the lipid, whereas the polar lipid fraction is the membrane component of the
360
DUCKETT AND WAGNER TABLE 2 Fatty Acid Composition (%) of the Polar Lipid before (RAW) and after Cooking (COOK)
Means for RAW and COOK differ (P , .05). SFA, saturated fatty acids (C14:0 1 C16:0 1 C18:0); MUFA, monounsaturated fatty acids (C16:1 1 C18:1); PUFA, polyunsaturated fatty acids (C18:2 1 C18:3 1 C20:4). ab c
cell. Fatty acid compositions of the fractions differ greatly, with polyunsaturated fatty acids located predominately in the membrane fraction (Sweeten et al., 1990; Duckett et al., 1993). These different distributions of fatty acids between storage and membrane fraction results in different responses with cooking. In the storage fraction (NL), cooking reduced the oleic acid and total MUFA content with a resultant increase in stearic acid and total SFA content. Similarly, Chang and Watts (1952) reported losses of oleic acid that were similar to the overall loss during cooking with moist heat. In the membrane fraction (PL), cooking reduced the percentage of linoleic and linolenic acids, and total PUFA, with a concomitant increase in stearic acid and total SFA content. In contrast, Terrell et al. (1968) reported losses of saturated fatty acids in the PL and unsaturated fatty acids in NL when cooking steaks. However, a different endpoint temperature (65°C) was used in that experiment. Overall, cooking reduced the content of oleic, linoleic, and linolenic acids and increased stearic acid content with no change in myristic or palmitic acids. These changes in the percentage of the various 18-carbon fatty acids indicate that oxidation occurred during cooking. In contrast, Harris et al. (1992) and Smith et al. (1989) reported no changes in the fatty acid composition of the total lipid of beefsteak after cooking. Thus, changes that occur with cooking might be overlooked if only the total lipid fraction is investigated or if the PUFA content in the muscle is low.
FATTY ACID COMPOSITION AFTER COOKING
361
TABLE 3 Changes in Fatty Acid Composition (%) of the Total Lipid before (RAW) and after Cooking (COOK)
Means for RAW and COOK differ (P , .05). SFA, saturated fatty acids (C14:0 1 C16:0 1 C18:0); MUFA, monounsaturated fatty acids (C16:1 1 C18:1); PUFA, polyunsaturated fatty acids (C18:2 1 C18:3 1 C20:4). ab c
The changes in fatty acid composition observed in this study with cooking represent an increase in the neutral fat content at the expense of hypocholesterolemic fat; however, the amount of hypercholesterolemic fat did not change. Both myristic and palmitic acids have been associated with increased plasma cholesterol levels in humans and thus are labeled hypercholesterolemic (Hegsted et al., 1965; Keys et al., 1965). Stearic (C18:0) acid,
FIG. 1. The amounts (g/130.5 g of RAW steak or 85.5 g of COOK steak) of hypercholesterolemic (C14:0 1 C16:0), neutral (C18:0), monounsaturated (MUFA), and polyunsaturated (PUFA) fatty acids in beef ribeye steak.
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another saturated fatty acid, is considered a neutral fat because it exerts neither a negative nor a positive effect on plasma cholesterol (Hegsted et al., 1965; Keys et al., 1965). More recently, diets high in stearic acid have been shown to be as effective as oleic acid in lowering plasma cholesterol levels when either acid replaces palmitic acid in the diet (Bonanome and Grundy, 1988). Mattson and Grundy (1985) found that diets high in oleic acid are as effective as those high in linoleic acid in reducing LDL cholesterol and that high oleic acid diets also reduce HDL cholesterol less frequently than those high in linoleic acid. Consumption of a 85.5-g (3 oz) serving of cooked beefsteak would contribute 2.4 g or 13% of its total calories as hypercholesterolemic fat. These values should warrant its continued dietary inclusion as a source of protein, iron, zinc, and B vitamins. REFERENCES Ahrens, E. H., Jr., Insull, W., Jr., Blomstrand, R., Hirsch, J., Tsaltas, T. T., and Peterson, M. L. (1957). The influence of dietary fats on serum lipid levels in man. Lancet 1, 943. Bonanome, A., and Grundy, S. M. (1988). Effect of dietary stearic acid on plasma cholesterol and lipoprotein levels. N. Engl. J. Med. 318, 1244. Chang, I. C. L., and Watts, B. M. (1952). The fatty acid content of meat and poultry before and after cooking. J. Am. Oil Chem. Soc. August, 334. Duckett, S. K., Wagner, D. G., Yates, L. D., Dolezal, H. G., and May, S. G. (1993). Effects of time on feed on beef nutrient composition. J. Anim. Sci. 71, 2079 –2088. Harris, K. B., Harberson, T. J., Savell, J. W., Cross, H. R., and Smith, S. B. (1992). Influences of quality grade, external fat level, and degree of doneness on beef steak fatty acids. J. Food Comp. Anal. 5, 84. Hegsted, D. M., McGandy, R. B., Meyers, M. L., and Stare, F. J. (1965). Quantitative effects of dietary fat on serum cholesterol in man. Am. J. Clin. Nutr. 17, 281. Keys, A., Anderson, J. T., and Grande, F. (1965). Serum cholesterol response to changes in the diet: IV. Particular saturated fatty acids in the diet. Metabolism 14, 776. Marmer, W. N., and Maxwell, R. J. (1981). Dry column method for the quantitative extraction and simultaneous class separation of lipids from muscle tissue. Lipids 16, 365. Mattson, F. H., and Grundy, S. M. (1985). Comparison of effects of dietary saturated, monounsaturated, polyunsaturated fatty acids on plasma lipids and lipoproteins in man. J. Lipid Res. 26, 194. Maxwell, R. J., and Marmer, W. N. (1983). Systemic protocol for accumulation of fatty acid data from multiple tissue samples: Tissue handling, lipid extraction and class separation, and capillary gas chromatographic analysis. Lipids 18, 453. Slover, H. T., and Lanza, E. (1979). Quantitative analysis of food fatty acids by capillary gas chromatography. J. Am. Oil Chem. Soc. 56, 933. Smith, D. R., Savell, J. W., Smith, S. B., and Cross, H. R. (1989). Fatty acids and proximate composition of raw and cooked retail cuts of beef trimmed to different external fat levels. Meat Sci. 26, 295. Sweeten, M. K., Cross, H. R., Smith, G. C., and Smith, S. B. (1990). Subcellular distribution and composition of lipids in muscle and adipose tissue. J. Food Sci. 55, 43. Terrell, R. N., Suess, G. G., Cassens, R. G., and Bray, R. W. (1968). Cooking, sex and interrelationships with carcass and growth characteristics and their effect on the neutral and phospholipid fatty J. Food Sci.
11, 357–362 (1998)
FC980600
Effect of Cooking on the Fatty Acid Composition of Beef Intramuscular Lipid1 S. K. Duckett2 and D. G. Wagner Department of Animal Science, Oklahoma State University, Stillwater, Oklahoma 74078, U.S.A. Received May 19, 1998, and in revised form September 10, 1998 Changes in fatty acid composition of neutral, polar and total lipid fractions of beef intramuscular lipid were assessed due to cooking. The longissimus muscle from 48 ribeye steaks was sectioned as: medial half for raw analysis (RAW) and lateral half for cooked analysis (COOK). Cooking reduced the percentages of oleic, linoleic, and linolenic acids and increased the percentage of stearic acid. These changes were most evident in the polar lipid fraction, where the unsaturated fatty acids occurred in the highest percentages. Overall, cooking increased the stearic acid and total saturated fatty acid contents of the intramuscular lipid while reducing total PUFA content. © 1998 Academic Press
INTRODUCTION The initial reports (Ahrens et al., 1957; Hegsted et al., 1965; Keys et al., 1965) of the relationship between dietary saturated fat intake and serum cholesterol levels has prompted concerns over the inclusion of beef products into a healthy diet. The intramuscular lipid of beefsteak contains over 50% of its fatty acids as unsaturated fatty acids (Duckett et al., 1993). Limited research is available to document changes in fatty acid composition with cooking. Harris et al. (1992) and Smith et al. (1989) found that cooking had little effect on the fatty acid composition of beef muscle total lipid extracts. However, fatty acid composition differs between lipid fractions (neutral lipid, storage fraction vs. polar lipid, membrane fraction) with the polyunsaturated fatty acids located primarily in the polar lipid (Sweeten et al., 1990; Duckett et al., 1993). Terrell et al. (1968) reported that cooking has a greater effect on the phospholipid (polar) fraction than the neutral lipid fraction. Thus, changes in fatty acid composition that occur during cooking may be overlooked when only total lipid extracts are analyzed. The objective of this study was to assess changes in fatty acid composition of the neutral lipid (NL), polar lipid (PL), and total lipid (TL) with cooking. MATERIALS AND METHODS Samples Forty-eight beef ribeye steaks (2.5 cm thick) were trimmed of all external fat and epimysial connective tissue. The steaks were then sectioned as: medial half for raw analysis (RAW) and lateral half for cooked analysis (COOK). The RAW steak was immediately pulverized in liquid nitrogen and stored at 220°C. The COOK steaks were 1
Approved for publication by the Director, Oklahoma Agricultural Experiment Station. To whom reprint requests should be addressed at current address: 216 Ag Science Bldg., University of Idaho, Moscow, ID 83844-2330. Fax: (208) 885-6420. E-mail: [email protected]. 2
357
0889-1575/98 $25.00 Copyright © 1998 by Academic Press All rights of reproduction in any form reserved.
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broiled on Farberware (Model 450A, Walter Kidde and Co., Bronx, NY) Open Hearth Broilers to an internal temperature of 70°C, as monitored by an Omega (Model OM 302-10) temperature logger equipped with copper constantan thermocouples. After cooling to room temperature, the COOK steaks were immediately pulverized in liquid nitrogen and stored at 220°C. Fatty Acids Samples were extracted using the dry column method (Marmer and Maxwell, 1981), which allows for the sequential elution of NL and PL. The NL (Slover and Lanza, 1979) and PL (Maxwell and Marmer, 1983) fractions were esterified to yield fatty acid methyl esters (FAME). The FAME were analyzed using a HP5890A gas chromatograph equipped with a flame-ionization detector and HP7673A automatic sampler (Hewlett–Packard Co., San Fernando, CA). Separations were accomplished on a 60-m SP2340 (Supelco, Bellefonte, PA) capillary column with a 0.25-mm internal diameter and 0.2-mm film thickness. The injector and detector were maintained at 280°C. Column oven temperature was programmed at 155–165°C at 0.5°C/min, 165–167°C at 0.2°C/min, and 167–200°C at 1.5°C/min and held at 200°C for 18 min. Data were collected and integrated by HP3365 ChemStation software (Hewlett–Packard Co.). Identification of fatty acids was based on retention times of reference compounds from Alltech (Alltech Associates, Deerfield, IL). Fatty acids were quantified by using an internal standard, methyl heneicosanoic acid (C21:0; Alltech Associates). Total lipid fatty acid profiles were calculated by multiplying the percentages of NL and PL in TL by each fatty acid. Statistical Analysis Paired t tests were used to analyze differences between the raw and cooked data. A significance level of P , .05 was used for all mean differences. RESULTS In the NL (Table 1), cooking reduced (P , .05) the percentage of palmitic (C16:0) acid and increased the percentage of stearic (C18:0) acid. Myristic (C14:0) acid was unchanged (P . .05) with cooking. These changes resulted in a 4% increase (P , .05) in the percentage of total saturated fatty acids (SFA) in the NL with cooking. The monounsaturated fatty acid (MUFA) content was reduced (P , .05) 5% after cooking due to a reduction (P , .05) in the oleic (C18:1) acid percentage. Palmitoleic (C16:1) acid was unchanged (P . .05) with cooking. The percentage of linoleic (C18:2) and arachidonic (C20:4) acids and the total polyunsaturated fatty acid (PUFA) content increased (P , .05) in the NL after cooking. Linolenic (C18:3) acid was not detected in the NL fraction. The percentage of unidentified fatty acids was higher (P , .05) in RAW than COOK. In the PL (Table 2), the percentage of myristic (C14:0) and stearic (C18:0) acids increased with cooking, whereas palmitic (C16:0) acid decreased in percentage. These changes resulted in a higher (P , .05) total SFA content for COOK steaks. The total MUFA content and the percentages of palmitoleic (C16:1) and oleic (C18:1) acids were unchanged (P . .05) with cooking. Linoleic (C18:2) and linolenic (C18:3) acids were reduced (P , .05) in percentage after cooking. Conversely, the percentage of arachidonic (C20:4) acid was increased in the cooked sample. The percentage of unidentified fatty
FATTY ACID COMPOSITION AFTER COOKING
359
TABLE 1 Fatty Acid Composition (%) of the Neutral Lipid before (RAW) and after Cooking (COOK)
Means for RAW and COOK differ (P , .05). SFA, saturated fatty acids (C14:0 1 C16:0 1 C18:0); MUFA, monounsaturated fatty acids (C16:1 1 C18:1); PUFA, polyunsaturated fatty acids (C18:2 1 C20:4). ab c
acids was higher (P , .05) in RAW than COOK. Overall, the total PUFA content of the PL was about 6% lower (P , .05) after cooking. In the TL (Table 3), the percentage of stearic (C18:0) acid and the total SFA content were increased (P , .05) 20 and 7% with cooking. Percentages of myristic (C14:0), palmitic (C16:0), palmitoleic (C16:1), and oleic (C18:1) acids and MUFA were unchanged (P . .05) with cooking in the TL. Cooking reduced (P , .05) the percentage of linoleic (C18:2), linolenic (C18:3), and arachidonic (C20:4) acids. The percentage of unidentified fatty acids was higher (P , .05) in RAW than COOK. The total PUFA content was about 29% lower (P , .05) after cooking. These changes in individual fatty acid percentage with cooking translated to differences in the amount (g/serving) of hypercholesterolemic fat (C14:0 1 C16:0), stearic (C18:0) acid, MUFA, and PUFA (Fig. 1). Intramuscular lipid retention was 99% during cooking and cooking shrink was 34.5%. Consumption of a 85.5-g (3 oz) serving of cooked beef ribeye steak would provide 2.4 g or about 13% of total calories as hypercholesterolemic (C14:0 1 C16:0) fat. DISCUSSION Cooking lean beefsteak with no external fat trim resulted in changes in the fatty acid composition between the lipid fractions. The neutral lipid fraction represents the storage component of the lipid, whereas the polar lipid fraction is the membrane component of the
360
DUCKETT AND WAGNER TABLE 2 Fatty Acid Composition (%) of the Polar Lipid before (RAW) and after Cooking (COOK)
Means for RAW and COOK differ (P , .05). SFA, saturated fatty acids (C14:0 1 C16:0 1 C18:0); MUFA, monounsaturated fatty acids (C16:1 1 C18:1); PUFA, polyunsaturated fatty acids (C18:2 1 C18:3 1 C20:4). ab c
cell. Fatty acid compositions of the fractions differ greatly, with polyunsaturated fatty acids located predominately in the membrane fraction (Sweeten et al., 1990; Duckett et al., 1993). These different distributions of fatty acids between storage and membrane fraction results in different responses with cooking. In the storage fraction (NL), cooking reduced the oleic acid and total MUFA content with a resultant increase in stearic acid and total SFA content. Similarly, Chang and Watts (1952) reported losses of oleic acid that were similar to the overall loss during cooking with moist heat. In the membrane fraction (PL), cooking reduced the percentage of linoleic and linolenic acids, and total PUFA, with a concomitant increase in stearic acid and total SFA content. In contrast, Terrell et al. (1968) reported losses of saturated fatty acids in the PL and unsaturated fatty acids in NL when cooking steaks. However, a different endpoint temperature (65°C) was used in that experiment. Overall, cooking reduced the content of oleic, linoleic, and linolenic acids and increased stearic acid content with no change in myristic or palmitic acids. These changes in the percentage of the various 18-carbon fatty acids indicate that oxidation occurred during cooking. In contrast, Harris et al. (1992) and Smith et al. (1989) reported no changes in the fatty acid composition of the total lipid of beefsteak after cooking. Thus, changes that occur with cooking might be overlooked if only the total lipid fraction is investigated or if the PUFA content in the muscle is low.
FATTY ACID COMPOSITION AFTER COOKING
361
TABLE 3 Changes in Fatty Acid Composition (%) of the Total Lipid before (RAW) and after Cooking (COOK)
Means for RAW and COOK differ (P , .05). SFA, saturated fatty acids (C14:0 1 C16:0 1 C18:0); MUFA, monounsaturated fatty acids (C16:1 1 C18:1); PUFA, polyunsaturated fatty acids (C18:2 1 C18:3 1 C20:4). ab c
The changes in fatty acid composition observed in this study with cooking represent an increase in the neutral fat content at the expense of hypocholesterolemic fat; however, the amount of hypercholesterolemic fat did not change. Both myristic and palmitic acids have been associated with increased plasma cholesterol levels in humans and thus are labeled hypercholesterolemic (Hegsted et al., 1965; Keys et al., 1965). Stearic (C18:0) acid,
FIG. 1. The amounts (g/130.5 g of RAW steak or 85.5 g of COOK steak) of hypercholesterolemic (C14:0 1 C16:0), neutral (C18:0), monounsaturated (MUFA), and polyunsaturated (PUFA) fatty acids in beef ribeye steak.
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another saturated fatty acid, is considered a neutral fat because it exerts neither a negative nor a positive effect on plasma cholesterol (Hegsted et al., 1965; Keys et al., 1965). More recently, diets high in stearic acid have been shown to be as effective as oleic acid in lowering plasma cholesterol levels when either acid replaces palmitic acid in the diet (Bonanome and Grundy, 1988). Mattson and Grundy (1985) found that diets high in oleic acid are as effective as those high in linoleic acid in reducing LDL cholesterol and that high oleic acid diets also reduce HDL cholesterol less frequently than those high in linoleic acid. Consumption of a 85.5-g (3 oz) serving of cooked beefsteak would contribute 2.4 g or 13% of its total calories as hypercholesterolemic fat. These values should warrant its continued dietary inclusion as a source of protein, iron, zinc, and B vitamins. REFERENCES Ahrens, E. H., Jr., Insull, W., Jr., Blomstrand, R., Hirsch, J., Tsaltas, T. T., and Peterson, M. L. (1957). The influence of dietary fats on serum lipid levels in man. Lancet 1, 943. Bonanome, A., and Grundy, S. M. (1988). Effect of dietary stearic acid on plasma cholesterol and lipoprotein levels. N. Engl. J. Med. 318, 1244. Chang, I. C. L., and Watts, B. M. (1952). The fatty acid content of meat and poultry before and after cooking. J. Am. Oil Chem. Soc. August, 334. Duckett, S. K., Wagner, D. G., Yates, L. D., Dolezal, H. G., and May, S. G. (1993). Effects of time on feed on beef nutrient composition. J. Anim. Sci. 71, 2079 –2088. Harris, K. B., Harberson, T. J., Savell, J. W., Cross, H. R., and Smith, S. B. (1992). Influences of quality grade, external fat level, and degree of doneness on beef steak fatty acids. J. Food Comp. Anal. 5, 84. Hegsted, D. M., McGandy, R. B., Meyers, M. L., and Stare, F. J. (1965). Quantitative effects of dietary fat on serum cholesterol in man. Am. J. Clin. Nutr. 17, 281. Keys, A., Anderson, J. T., and Grande, F. (1965). Serum cholesterol response to changes in the diet: IV. Particular saturated fatty acids in the diet. Metabolism 14, 776. Marmer, W. N., and Maxwell, R. J. (1981). Dry column method for the quantitative extraction and simultaneous class separation of lipids from muscle tissue. Lipids 16, 365. Mattson, F. H., and Grundy, S. M. (1985). Comparison of effects of dietary saturated, monounsaturated, polyunsaturated fatty acids on plasma lipids and lipoproteins in man. J. Lipid Res. 26, 194. Maxwell, R. J., and Marmer, W. N. (1983). Systemic protocol for accumulation of fatty acid data from multiple tissue samples: Tissue handling, lipid extraction and class separation, and capillary gas chromatographic analysis. Lipids 18, 453. Slover, H. T., and Lanza, E. (1979). Quantitative analysis of food fatty acids by capillary gas chromatography. J. Am. Oil Chem. Soc. 56, 933. Smith, D. R., Savell, J. W., Smith, S. B., and Cross, H. R. (1989). Fatty acids and proximate composition of raw and cooked retail cuts of beef trimmed to different external fat levels. Meat Sci. 26, 295. Sweeten, M. K., Cross, H. R., Smith, G. C., and Smith, S. B. (1990). Subcellular distribution and composition of lipids in muscle and adipose tissue. J. Food Sci. 55, 43. Terrell, R. N., Suess, G. G., Cassens, R. G., and Bray, R. W. (1968). Cooking, sex and interrelationships with carcass and growth characteristics and their effect on the neutral and phospholipid fatty J. Food Sci.