- Email: [email protected]
Evaluating the Cooking and Chemical Characteristics of Low-Fat Ground Beef Patties
(2000) 13, 253}264 doi: 10.1006/jfca.2000.0878 Available online at http://www.idealibrary.com on
JOURNAL OF FOOD COMPOSITION AND ANALYSIS
ORIGINAL ARTICLE Evaluating the Cooking and Chemical Characteristics of Low-Fat Ground Beef Patties Jeanette M. Kirchner, Lisa C. Beasley, Kerri B. Harris, Je!rey W. Savell Meat Science Section, Room 348, Kleberg Center, Department of Animal Science, Texas A&M University, Texas Agricultural Experiment Station, College Station, TX 77843-2471, U.S.A. Received September 7, 1998, and in revised form January 4, 2000
Ground beef patties (n"504), manufactured to contain 5, 10 or 15% fat, were evaluated to determine the e!ects of preparation, storage and cooking methods, and degree of doneness on cholesterol, total lipid, protein, moisture, and energy content. Di!erences between fresh, handmade patties and frozen, machine-made patties were statistically signi"cant for some nutrients. However, these di!erences may be insigni"cant to consumers because actual di!erences were small. The greatest di!erence in composition of the cooked ground beef patties was observed between patties cooked from the frozen state versus fresh patties. Patties cooked from the frozen state were higher in total lipid for each cooking method. An evaluation of cooking methods revealed small di!erences in total lipid content at the 5% level; however, at the 10 and 15% total lipid levels, microwaved and reheated patties contained the lowest amounts of total lipid while those baked, pan-fried, and broiled contained higher levels. In all total lipid levels and cooking methods except 5% fat broiled/reheated patties, reheating led to a decrease in fat content. Decreases in total lipid content were seen for reheated pan-fried patties at the 5 and 10% levels and reheated patties at the 15% level. 2000 Academic Press Key Words: beef; patties; cooking methods.
INTRODUCTION It is well documented that diet plays an important role in the prevention and treatment of coronary heart disease, the leading cause of death for Americans (Council for Agricultural Science and Technology, 1985). As a result of the linkage between diet and health, health-conscious consumers have created a demand for healthful food products that help prevent or reduce the risk of disease. The message from consumers to the meat industry is for leaner beef (Savell et al., 1989) with supermarkets responding by marketing leaner and more closely trimmed cuts of beef (Savell et al., 1991). Savell et al. (1991) showed that the distribution of ground beef in the retail case was 37% regular (24% fat), 40% lean (19% fat) and over 22% extra lean (as low as 10% fat). This revealed that retail ground beef was lower in fat than the USDA (1990) Agriculture Handbook 8-13, which designates extra lean ground beef as 17.1% fat. In the U.S., the marketing of very low-fat ground beef (5}10% range) has increased since the early 1990s; however, little information is available regarding the nutrient To whom correspondence and reprint requests should be addressed. Tel.: 979-845-3935, Fax: 979-8459454. E-mail: [email protected] 0889}1575/00/030253#12 $35.00/0
2000 Academic Press
254
KIRCHNER E¹ A¸.
content of very low-fat ground beef. The USDA Handbook 8-13 (USDA, 1990), which serves as a nutrient data bank for beef, lacks information on very low-fat ground beef. Signi"cant composition di!erences may exist between fresh and frozen patties, depending on cooking method; therefore, determining the cooking and chemical characteristics of very low-fat ground beef is a necessary task. The objectives of this study were to evaluate the e!ects of cooking method, degree of doneness, and patty form (fresh, hand-made or frozen, machine-made) on cholesterol and proximate composition (total lipid, protein, moisture, energy content) of ground beef manufactured to contain 5, 10 or 15%. METHODS Formulation of Patties Beef was obtained and processed at the E.M. Rosenthal Meat Science and Technology Center at Texas A&M University. Ground beef patties were formulated to contain 5, 10 or 15% fat. To achieve the desired end point fat targets more easily, beef inside rounds (IMPS C168; USDA, 1996) were used as the lean source for the 5% patties, and beef shoulder clods (IMPS C114; USDA, 1996) were used in the 10 and 15% fat formulations. All subcutaneous and intermuscular fat was removed from the muscles and used as the fat source. Lean and fat sources (approx. 13C) were ground separately through a 4.7 mm plate, and the fat content of each was determined using a CEM model AVC-80 automatic fat extraction system. A Pearson square (Pearson and Tauber, 1984) was used to determine the amount of fat and lean sources to be added to the batch before a "nal grind through a 3.2 mm plate. Nine batches (n"3 per fat level) of 56 patties each (total of 504 patties) were mixed for cooking and chemical analyses. The actual average percentage fat of the 5, 10, and 15% fat levels were 4.99, 10.13, and 14.89%, respectively. The ground beef was formed into either hand- or machine-made patties using a Tupperware patty forming ring or a Hollymatic Patty Machine, respectively. Handmade patties were placed in sealed plastic bags and stored overnight at 23C until cooked. Machine-made patties were placed in stacks of 8}10 with patty liners between each patty, sealed in plastic bags, boxed and held at !103C for less than one week until they were cooked directly from the frozen state. The hand-made patties were approximately 9 cm in diameter, 1.5 cm in thickness and weighed 115 g, while machine-made patties averaged 11 cm in diameter, 1.2 cm in thickness and weighed 117 g. Cooking Procedure The cooking methods used were: microwaving, microwave reheating, broiling, panfrying, and baking. Patties were cooked to either medium or well-done for all cooking methods except microwave reheating. Reheating was only performed for pan-fried and broiled patties. To determine the optimum degree of doneness, preliminary cooking trials were conducted for each fat level and cooking method. Patties were evaluated by appearance (a color photograph chart was used to estimate degree of doneness), then adjustments were made in cooking times until a medium or well-done patty was obtained. (It should be noted that cooking end point before consumption should be checked with a thermometer rather than appearance.) For each fat level and cooking method, the cooking time varied (Table 1). Cooking procedures followed American
255
CHARACTERISTICS OF LOW-FAT GROUND BEEF PATTIES TABLE 1
Cooking times of fresh, hand-made and frozen, machine-made ground beef patties, varying in fat level, cooking method, and degree of doneness Fat level Cooking method Microwave Fresh Medium Well-done Frozen Medium Well-done Broil Fresh Medium Well-done Frozen Medium Well-done Pan-fry Fresh Medium Well-done Frozen Medium Well-done Bake Fresh Medium Well-done Frozen Medium Well-done
5%
10%
15%
1.20, 1.15 1.35, 1.35
1.15, 1.15 1.20, 1.20
1.10, 1.10 1.25, 1.25
1.20, 1.20 1.35, 1.35
1.15, 1.15 1.20, 1.20
1.15, 1.15 1.25, 1.25
8.00, 7.30 10.00, 9.30
7.00, 7.00 9.00, 9.00
5.00, 4.30 1.25, 1.25
6.30, 6.30 8.00, 8.00
6.30, 6.00 7.30, 7.30
6.00, 5.30 7.00, 7.00
4.00, 4.00 5.30, 5.30
4.00, 3.30 5.30, 5.00
3.30, 3.30 5.00, 5.00
4.00, 4.00 5.00, 5.00
4.00, 4.00 5.00, 4.30
3.30, 3.30 5.00, 4.30
25.00 28.00
21.00 25.00
19.00 23.00
24.00 27.00
23.00 25.00
22.00 25.00
Cooking times are recorded in minutes per side. Patties were turned once. Microwave reheating time for fresh broiled and pan-fried patties was 1.15 min defrost and 0.5 min reheat. Microwave reheating time for frozen broiled and pan-fried patties was 1.00 min defrost and 1.00 min reheat.
Meat Science Association (1978) guidelines when applicable. Listed are descriptions of the cooking methods: (a) Microwaving: Patties were cooked separately on a pre-heated browning dish in a Kenmore microwave oven (power consumption: 1580 W) using the high-power setting. (b) Microwave reheating: Previously broiled and pan-fried patties were packaged in plastic wrap and aluminum foil and stored in the freezer at !103C. Frozen patties were then placed on a plate in a microwave oven (same as above) to be defrosted and heated at the high-power setting. (c) Broiling: Two patties were cooked simultaneously on a pre-heated electric Farberware Open-Hearth Broiler.
256
KIRCHNER E¹ A¸. TABLE 2
Fat content (g per cooked patty) means (S.D.) for cooking method, degree of doneness, and patty form Fat level Treatment parameter Cooking method Microwave (n"24) Broil (n"24) Broil/reheat (n"24) Pan-fry (n"24) Pan-fry/reheat (n"24) Bake (n"24) Degree of doneness Medium (n"72) Well-done (n"72) Patty form Fresh, hand-made (n"72) Frozen, machine-made (n"72) 1,2,3
5%
10%
15%
6.3 (0.52) 6.7 (0.62) 6.8 (0.53) 6.9 (0.57) 6.4 (0.41) 6.8 (0.52)
9.6 (1.42) 11.3 (1.39) 10.4 (1.32) 11.1 (0.90) 10.2 (1.44) 11.2 (1.17)
11.8 (1.80) 14.1 (2.06) 12.6 (1.79) 13.6 (1.55) 12.5 (1.21) 13.9 (1.52)
6.7 (0.57) 6.5 (0.55)
10.7 (1.44) 10.5 (1.37)
13.4 (1.99) 12.8 (1.66)
6.3 (0.48) 6.9 (0.46)
9.8 (1.17) 11.5 (1.04)
11.8 (1.21) 14.4 (1.36)
Means within a treatment parameter and column having di!erent superscripts are di!erent (P(0.05).
(d) Pan-frying: Patties were placed individually in a pre-heated West Bend electric skillet at 1633C. A spot check surface thermometer was used to calibrate the skillet. (e) Baking: Two patties were put on a wire rack with a cookie sheet underneath and placed in an oven pre-heated to 1773C. For all cooking methods, juices were allowed to drain from the patties. Broiled and baked patties were cooked on wire racks, which allowed drip loss to occur during cooking. Pan-fried and microwaved patties were drained after cooking by tilting the patty with a spatula and permitting fat to drain. Weights of the raw, cooked, and reheated patties were recorded, and the patty was then minced in a Cuisinart food processor. Portions of each sample were placed in air-tight polypropylene amber vials and frozen at !103C for subsequent chemical analyses. Determination of Fat Content A modi"ed Folch et al. (1957) method of total lipid extraction was performed. A 5 g sample was homogenized with 75 mL of chloroform : methanol (2 : 1) for 3 min using a Virtis homogenizer. The homogenate was "ltered through Whatman No. 42 "lter paper with slight suction. The meat residue and "lter paper were rehomogenized for 3 min with 5 mL of chloroform : methanol (2 : 1) and then "ltered into the same Erlenmeyer #ask using new "lter paper. The combined "ltrate was transferred to
257
CHARACTERISTICS OF LOW-FAT GROUND BEEF PATTIES TABLE 3
Protein content (g per cooked patty) means (S.D.) for cooking method, degree of doneness, and patty form Fat level Treatment parameter Cooking method Microwave (n"24) Broil (n"24) Broil/reheat (n"24) Pan-fry (n"24) Pan-fry/reheat (n"24) Bake (n"24) Degree of doneness Medium (n"72) Well-done (n"72) Patty form Fresh, hand-made (n"72) Frozen, machine-made (n"72) 1,2,3
5%
10%
15%
26.0 (0.63) 25.31}3 (1.28) 25.21}3 (1.46) 25.0 (1.32) 24.5 (0.72) 25.5 (1.18)
22.2 (0.92) 22.2 (1.00) 21.3 (1.64) 21.9 (0.91) 21.8 (1.07) 22.3 (1.26)
21.1 (0.92) 20.8 (1.03) 20.8 (1.36) 21.2 (1.46) 20.5 (1.13) 20.6 (0.90)
25.3 (1.33) 25.2 (1.09)
21.8 (1.08) 22.1 (1.29)
20.8 (1.14) 20.9 (1.20)
24.9 (1.06) 25.6 (1.26)
21.9 (1.38) 22.0 (0.98)
20.7 (1.13) 21.0 (1.20)
Means within a treatment parameter and column having di!erent superscripts are di!erent (P(0.05).
a 500 mL separatory funnel, 25 mL distilled water was added and the phases were allowed to separate. The lower phase in the funnel (organic phase) was drained from the funnel into a 100 mL volumetric #ask. The organic phase was brought to 100 mL volume with pure chloroform. Any aqueous phase was removed, and the volume was again brought to 100 mL using pure chloroform. The contents were transferred into large Te#on-coated, screw-cap test tubes, capped with nitrogen, and stored at !103C until analyzed. Total lipid analysis for each patty was determined in triplicate using 10 mL of extract. The solvent was evaporated at room temperature in the fume hood, and the samples were dried at 1003C for 1 h. The mean patty fat content was computed by averaging the triplicates. Determination of Cholesterol, Protein and Moisture Content Cholesterol content for each patty was determined in triplicate using the procedure of Bohac et al. (1988). The mean patty cholesterol content was computed by averaging the triplicates. Protein for each patty was determined in triplicate using an AOAC (1990) approved Kjedahl block digestion method. The mean patty protein content was computed by averaging the triplicates. Moisture content of each patty was measured using an AOAC (1990) oven-drying procedure.
258
KIRCHNER E¹ A¸. TABLE 4
Moisture content (g per cooked patty) means (S.D.) for cooking method, degree of doneness, and patty form Fat level Treatment parameter Cooking method Microwave (n"24) Broil (n"24) Broil/reheat (n"24) Pan-fry (n"24) Pan-fry/reheat (n"24) Bake (n"24) Degree of doneness Medium (n"72) Well-done (n"72) Patty form Fresh, hand-made (n"72) Frozen, machine-made (n"72)
5%
10%
15%
54.5 (3.77) 52.9 (5.31) 44.4 (6.92) 58.8 (4.59) 51.0 (3.43) 57.0 (2.71)
49.6 (2.70) 49.9 (4.62) 41.4 (4.49) 53.6 (4.40) 46.6 (5.24) 57.6 (2.92)
46.1 (2.54) 49.8 (6.30) 41.0 (5.54) 50.5 (5.10) 43.1 (4.29) 51.7 (2.92)
55.7 (5.49) 50.5 (6.46)
52.1 (6.25) 47.5 (6.08)
49.8 (5.30) 44.2 (5.48)
53.4 (7.48) 52.8 (5.44)
50.9 (6.61) 48.7 (6.36)
49.2 (5.50) 44.8 (5.83)
1,2,3,4,5 Means within a treatment parameter and column having di!erent superscripts are di!erent (P(0.05).
Cooking >ields and Fat Retention Percentage cooking yields and fat retention were determined for each sample using raw versus cooked data as described by Jones et al. (1992) and Murphy et al. (1975). The equations follow: Cooking yield (%)"(cooked weight)/(raw weight);100, Fat retention (%)"(% fat in cooked lean)/(% fat in raw lean);% cooking yield. Statistical Analyses Analysis of variance was applied to these data to determine signi"cant treatment e!ects. When P(0.05 di!erences were found, Student}Newman}Keuls procedure was used to determine di!erences between means within a fat percentage. These analyses were performed for cooking methods, degree of doneness and patty state for fat, protein, moisture, cholesterol, fat retention, cooking yield, and energy content (SAS, 1988).
259
CHARACTERISTICS OF LOW-FAT GROUND BEEF PATTIES
TABLE 5 Cholesterol content (mg per cooked patty) means (S.D.) for cooking method, degree of doneness, and patty form Fat level Treatment parameter Cooking method Microwave (n"24) Broil (n"24) Broil/reheat (n"24) Pan-fry (n"24) Pan-fry/reheat (n"24) Bake (n"24) Degree of doneness Medium (n"72) Well-done (n"72) Patty form Fresh, hand-made (n"72) Frozen, machine-made (n"72)
5%
10%
15%
68.7 (7.51) 65.9 (10.38) 66.5 (11.05) 68.6 (9.48) 69.0 (6.97) 64.8 (9.16)
69.0 (6.78) 69.4 (8.57) 67.5 (10.47) 75.0 (9.33) 67.2 (10.26) 73.5 (10.15)
67.9 (7.61) 68.4 (9.98) 68.4 (7.50) 69.9 (10.34) 63.4 (8.93) 71.6 (5.32)
68.2 (9.10) 66.3 (9.24)
70.6 (10.09) 69.9 (9.25)
69.2 (9.31) 67.3 (7.95)
66.5 (8.46) 68.0 (9.86)
69.8 (10.24) 70.7 (9.08)
67.8 (7.63) 68.7 (9.65)
Means within a treatment parameter and column having di!erent superscripts are di!erent (P(0.05).
RESULTS AND DISCUSSION Means values of fat expressed as grams per patty for fresh and frozen ground beef varying in fat level, cooking method, degree of doneness and patty form are shown in Table 2. Evaluating signi"cant di!erences by patty rather than by weight is more appropriate because that is how the patty will be consumed. Patties cooked from the frozen state were higher in fat for each cooking method; the di!erential between fresh and frozen patties appeared to be the greatest at the 15% level. These di!erences may be accounted for by initial di!erences in size and density seen between raw (fresh and frozen) patties. Frozen, machine-made patties developed an outer surface skin that may have retained fat during cooking. This, in combination with the theory that a denser machine-made patty may allow less fat to be lost during cooking, may explain the di!erences between compact frozen machine-made patties and fresh hand-made patties. Within each fat level treatment, microwaved patties tended to have less fat than patties from the other cooking methods. As expected, the values for protein content (Table 3) decreased as initial fat level increased. Values within a fat level were similar, and protein content remained relatively constant among cooking methods and between degrees of doneness. Moisture content (Table 4) showed wide variability among and between treatments due to how the patties were made, what degree of doneness they were cooked to, and the cooking method employed, especially those methods where reheating was used.
260
KIRCHNER E¹ A¸. TABLE 6 Percentage cooking yield means (S.D.) for cooking method, degree of doneness, and patty form Fat level
Treatment parameter Cooking method Microwave (n"24) Broil (n"24) Broil/reheat (n"24) Pan-fry (n"24) Pan-fry/reheat (n"24) Bake (n"24) Degree of doneness Medium (n"72) Well-done (n"72) Patty form Fresh, hand-made (n"72) Frozen, machine-made (n"72)
5%
10%
15%
74.8 (3.54) 73.6 (4.99) 65.2 (4.59) 78.8 (4.60) 71.5 (3.39) 77.2 (3.16)
73.7 (3.14) 72.7 (4.74) 64.4 (4.88) 85.5 (4.02) 78.4 (4.64) 79.4 (2.79)
69.2 (3.44) 74.9 (6.49) 65.3 (3.66) 75.0 (5.07) 66.8 (3.00) 75.6 (3.77)
75.6 (5.33) 71.5 (5.93)
74.2 (6.21) 70.0 (5.72)
73.7 (5.68) 68.5 (5.21)
74.3 (6.79) 72.8 (4.96)
72.6 (6.81) 71.6 (5.78)
71.9 (5.93) 70.3 (6.07)
1,2,3,4,5 Means within a treatment parameter and column having di!erent superscripts are di!erent (P(0.05).
TABLE 7 Percentage fat retention means (S.D.) for patty form (fresh, hand-made or frozen, machine-made) Fat level Treatment parameter Patty form Fresh, hand-made (n"72) Frozen, machine-made (n"72)
5%
10%
15%
94.5 (7.19) 94.3 (8.93)
77.9 (9.36) 85.5 (7.72)
67.9 (6.98) 108.3 (10.25)
Means within columns having di!erent superscripts are di!erent (P(0.05).
Absolute moisture content values on a per patty basis ranged about 10% points from the highest to the lowest values. It is important to understand the interrelationships of these factors on moisture content because of its relationship to the ultimate eating qualities of the cooked patty. Attempts should be made to use cooking methods that maintain higher levels of moisture to ensure adequate patty juiciness. Cholesterol content of fresh and frozen raw patties was not related to the initial fat level (Table 5), and there were no consistent trends among cooking methods within or across fat levels. This "nding concurs with previous research that found no
261
CHARACTERISTICS OF LOW-FAT GROUND BEEF PATTIES TABLE 8
Percentage fat retention mean (S.D.) for cooking method and degree of doneness of frozen, machine-made patties Fat level Treatment Cooking method Microwave (n"12) Broil (n"12) Broil/reheat (n"12) Pan-fry (n"12) Pan-fry/reheat (n"12) Bake (n"12) Degree of doneness Medium (n"36) Well-done (n"36)
5%
10%
15%
92.0 (3.19) 97.1 (4.68) 91.3 (5.40) 96.1 (7.88) 88.9 (5.27) 96.3 (4.70)
78.3 (6.12) 91.7 (5.60) 84.3 (6.07) 87.4 (4.49) 83.0 (9.60) 88.7 (6.79)
99.8 (5.71) 117.9 (12.33) 104.0 (7.96) 111.4 (7.46) 104.0 (8.60) 112.0 (7.64)
94.3 (5.81) 92.9 (6.22)
86.9 (7.85) 84.3 (7.49)
111.6 (10.81) 104.9 (8.55)
1,2,3 Means within a treatment parameter and column having di!erent superscripts are di!erent (P(0.05).
TABLE 9 Percentage fat retention mean (S.D.) for cooking method and degree of doneness of fresh, hand-made patties Fat level Treatment parameter Cooking method Microwave (n"12) Broil (n"12) Broil/reheat (n"12) Pan-fry (n"12) Pan-fry/reheat (n"12) Bake (n"12) Degree of doneness Medium (n"36) Well-done (n"36)
5%
10%
15%
87.8 (3.96) 92.2 (6.39) 97.8 (5.07) 99.5 (7.30) 92.9 (5.77) 96.8 (7.90)
69.1 (9.54) 81.4 (7.67) 76.0 (8.37) 83.7 (5.81) 73.8 (8.82) 83.2 (6.85)
59.4 (6.63) 72.6 (5.89) 64.0 (4.13) 70.8 (3.51) 66.9 (4.03) 73.4 (5.17)
95.5 (7.31) 93.5 (7.04)
78.1 (9.35) 77.6 (9.49)
68.6 (6.68) 67.1 (7.29)
1,2,3,4 Means within a treatment parameter and column having di!erent superscripts are di!erent (P(0.05).
262
KIRCHNER E¹ A¸. TABLE 10
Energy content (kJ per cooked patty) means (S.D.) for cooking method, degree of doneness, and patty form Fat level Treatment parameter Cooking method Microwave (n"12) Broil (n"24) Broil/reheat (n"24) Pan-fry (n"24) Pan-fry/reheat (n"24) Bake (n"24) Degree of doneness Medium (n"72) Well-done (n"72) Patty form Fresh, hand-made (n"72) Frozen, machine-made (n"72)
5%
10%
15%
601 (15.0) 602 (29.8) 592 (26.1) 604 (23.6) 580 (19.4) 609 (27.7)
654 (50.2) 709 (43.9) 667 (47.8) 701 (33.7) 665 (40.2) 708 (40.4)
712 (65.1) 786 (70.5) 732 (73.8) 773 (57.6) 726 (38.5) 774 (53.5)
598 (25.4) 598 (25.9)
686 (50.0) 682 (48.2)
759 (68.2) 742 (63.2)
594 (23.9) 602 (26.7)
661 (49.6) 707 (36.0)
708 (45.8) 793 (55.6)
1,2,3 Means within a treatment parameter and column having di!erent superscripts are di!erent (P(0.05).
signi"cant relationship between fat level and cholesterol content (Hoelscher et al., 1987). Whether the patty was fresh or frozen had no signi"cant bearing on cholesterol content. Mean values for percentage cooking yield are shown in Table 6. Cooking yield varied little as fat percentage increased. This was due to more fat being lost at the 15% fat level, and more moisture lost at the 5% fat level, thus equalizing values. Well-done patties, as would be expected, had a lower cooking yield than patties cooked to a medium degree of doneness. Cooking yield was lowest for broiled/reheated patties. There was a signi"cant interaction between fat level and patty form (Table 7). As fat level increased, the magnitude of the di!erence between fresh, hand-made and frozen, machine-made increased substantially. Thus, data were analyzed separately for each patty form treatment and are reported in Tables 8 & 9. For frozen patties (Table 8), those microwaved, broiled/reheated, and pan-fried/reheated retained less fat than the other patties evaluated. Fresh, hand-made patties showed no consistent trends within fat levels (Table 9). Cooking retentions were the highest (and in some cases exceeded 100%) for the 15% fat level treatment. Degree of doneness had little or no e!ect on fat retention, regardless of whether the patties were cooked from the fresh or frozen state. In contrast to the "ndings reported in Table 8, fat retention was considerably lower for the 15% fat level treatment. For comparisons of energy content, microwaved and reheated patties contained statistically less energy (but with no practical signi"cance) than other cooking
CHARACTERISTICS OF LOW-FAT GROUND BEEF PATTIES
263
methods (Table 10). Cooking to medium or well-done had no e!ect on energy value because moisture content (no nutritive value) was the only proximate analysis a!ected by doneness. With increasing fat content levels, those patties that were frozen, machine-made had higher energy content than those that were fresh, hand-made. This was due primarily to the fat retention di!erences discussed previously. Sheard et al. (1998) found that burgers from the fattest categories they studied lost about 30% of the energy upon cooking; however, the low-fat burgers, when fried in vegetable oil, increased in energy.
CONCLUSIONS The primary objective of this study was to provide nutrient data for low-fat ground beef using preparation methods practiced by today's consumer. These data will aid consumers, dietitians, and scientists by providing nutrient values and trends for a comprehensive list of cooking methods using fresh, hand-made and frozen, machine-made patties. Even though di!erences in energy content were statistically signi"cant between fresh and frozen patties, the average di!erence was minimal. For most consumers, this reduction is insigni"cant. Microwaving and reheating patties also resulted in reduced energy, but again the di!erences would likely be insigni"cant to consumers. For ground beef containing 5}15% fat, fat and energy content varied little between cooking methods. Individuals watching fat and caloric intake would bene"t from the knowledge that they could choose 5}15% fat ground beef and use a variety of cooking methods, whereas a consumer choosing higher-fat ground beef is limited to certain cooking methods if they wish to reduce the amount of fat and energy they consume. No consistent trends in cholesterol content were found between fat levels, cooking methods, degrees of doneness or patty states. This information will allow those individuals concerned about cholesterol intake to be less restricted in their diet without increasing dietary cholesterol.
REFERENCES American Meat Science Association (1978). Guidelines for Cookery and Sensory Evaluation of Meat. National Live Stock and Meat Board, Chicago, IL. AOAC (1990). O.cial Methods of Analysis, 15 edn. Association of O$cial Analytical Chemists, Washington, DC. Bohac, C. E., Rhee, K. S., Cross, H. R., and Ono, K. (1988). Assessment of methodologies for colorimetric cholesterol assay of meats. J. Food Sci. 53, 1642}1644. Council for Agricultural Science and Technology (1985). Diet and coronary heart disease. Report No. 107. United States Department of Agriculture, Washington, DC. Folch, J., Lees, M., and Stanley, G. H. S. (1957). A simple method for isolation and puri"cation of lipids from animal tissues. J. Biol. Chem. 226, 497}509. Hoelscher, L. M., Savell, J. W., Harris, J. M., Cross, H. R., and Rhee, K. S. (1987). E!ect of initial fat level and cooking method on cholesterol content caloric value of ground beef patties. J. Food Sci. 52, 883}885. Jones, D. K., Savell, J. W., and Cross, H. R. (1992). E!ects of fat trim on the composition of beef retail cuts * 3. Cooking yields and fat retention of the separable lean. J. Muscle Foods 3, 73}81. Murphy, E. W., Criner, P. E., and Gray, B. C. (1975). Comparisons of methods for calculating retentions of nutrients in cooked foods. J. Agric. Food Chem. 23, 1153}1157. Pearson, A. M., and Tauber, F. W. (1984). Processed Meats, 2nd edn. Van Nostrand Reinhold Co., New York, NY. SAS (1988). SAS ;sers Guide: Statistics. SAS Institute, Cary, NC.
264
KIRCHNER E¹ A¸.
Savell, J. W., Cross, H. R., Francis, J. J., Wise, J. W., Hale, D. S., Wilkes, D. L., and Smith, G. C. (1989). National Consumer Retail Beef Study: Interaction of trim level, price and grade on consumer acceptance of beef steaks and roasts. J. Food Qual. 12, 251}274. Savell, J. W., Harris, J. J., Cross, H. R., Hale, D. S., and Beasley, L. C. (1991). National Beef Market Basket Survey. J. Anim. Sci. 69, 2883}2893. Sheard, P. R., Nute, G. R., and Chappell, A. G. (1998). The e!ect of cooking on the chemical composition of meat products with special reference to fat loss. Meat Sci. 49, 175}191. USDA (1990). Composition of Foods: Beef Products: Raw, Processed, and Prepared. Agriculture Handbook No. 8-13. United States Department of Agriculture, Washington, DC. USDA (1996). Institutional Meat Purchase Speci,cations for Fresh Beef Products: Series 100. Agricultural Marketing Service, United States Department of Agriculture, Washington, DC.
JOURNAL OF FOOD COMPOSITION AND ANALYSIS
ORIGINAL ARTICLE Evaluating the Cooking and Chemical Characteristics of Low-Fat Ground Beef Patties Jeanette M. Kirchner, Lisa C. Beasley, Kerri B. Harris, Je!rey W. Savell Meat Science Section, Room 348, Kleberg Center, Department of Animal Science, Texas A&M University, Texas Agricultural Experiment Station, College Station, TX 77843-2471, U.S.A. Received September 7, 1998, and in revised form January 4, 2000
Ground beef patties (n"504), manufactured to contain 5, 10 or 15% fat, were evaluated to determine the e!ects of preparation, storage and cooking methods, and degree of doneness on cholesterol, total lipid, protein, moisture, and energy content. Di!erences between fresh, handmade patties and frozen, machine-made patties were statistically signi"cant for some nutrients. However, these di!erences may be insigni"cant to consumers because actual di!erences were small. The greatest di!erence in composition of the cooked ground beef patties was observed between patties cooked from the frozen state versus fresh patties. Patties cooked from the frozen state were higher in total lipid for each cooking method. An evaluation of cooking methods revealed small di!erences in total lipid content at the 5% level; however, at the 10 and 15% total lipid levels, microwaved and reheated patties contained the lowest amounts of total lipid while those baked, pan-fried, and broiled contained higher levels. In all total lipid levels and cooking methods except 5% fat broiled/reheated patties, reheating led to a decrease in fat content. Decreases in total lipid content were seen for reheated pan-fried patties at the 5 and 10% levels and reheated patties at the 15% level. 2000 Academic Press Key Words: beef; patties; cooking methods.
INTRODUCTION It is well documented that diet plays an important role in the prevention and treatment of coronary heart disease, the leading cause of death for Americans (Council for Agricultural Science and Technology, 1985). As a result of the linkage between diet and health, health-conscious consumers have created a demand for healthful food products that help prevent or reduce the risk of disease. The message from consumers to the meat industry is for leaner beef (Savell et al., 1989) with supermarkets responding by marketing leaner and more closely trimmed cuts of beef (Savell et al., 1991). Savell et al. (1991) showed that the distribution of ground beef in the retail case was 37% regular (24% fat), 40% lean (19% fat) and over 22% extra lean (as low as 10% fat). This revealed that retail ground beef was lower in fat than the USDA (1990) Agriculture Handbook 8-13, which designates extra lean ground beef as 17.1% fat. In the U.S., the marketing of very low-fat ground beef (5}10% range) has increased since the early 1990s; however, little information is available regarding the nutrient To whom correspondence and reprint requests should be addressed. Tel.: 979-845-3935, Fax: 979-8459454. E-mail: [email protected] 0889}1575/00/030253#12 $35.00/0
2000 Academic Press
254
KIRCHNER E¹ A¸.
content of very low-fat ground beef. The USDA Handbook 8-13 (USDA, 1990), which serves as a nutrient data bank for beef, lacks information on very low-fat ground beef. Signi"cant composition di!erences may exist between fresh and frozen patties, depending on cooking method; therefore, determining the cooking and chemical characteristics of very low-fat ground beef is a necessary task. The objectives of this study were to evaluate the e!ects of cooking method, degree of doneness, and patty form (fresh, hand-made or frozen, machine-made) on cholesterol and proximate composition (total lipid, protein, moisture, energy content) of ground beef manufactured to contain 5, 10 or 15%. METHODS Formulation of Patties Beef was obtained and processed at the E.M. Rosenthal Meat Science and Technology Center at Texas A&M University. Ground beef patties were formulated to contain 5, 10 or 15% fat. To achieve the desired end point fat targets more easily, beef inside rounds (IMPS C168; USDA, 1996) were used as the lean source for the 5% patties, and beef shoulder clods (IMPS C114; USDA, 1996) were used in the 10 and 15% fat formulations. All subcutaneous and intermuscular fat was removed from the muscles and used as the fat source. Lean and fat sources (approx. 13C) were ground separately through a 4.7 mm plate, and the fat content of each was determined using a CEM model AVC-80 automatic fat extraction system. A Pearson square (Pearson and Tauber, 1984) was used to determine the amount of fat and lean sources to be added to the batch before a "nal grind through a 3.2 mm plate. Nine batches (n"3 per fat level) of 56 patties each (total of 504 patties) were mixed for cooking and chemical analyses. The actual average percentage fat of the 5, 10, and 15% fat levels were 4.99, 10.13, and 14.89%, respectively. The ground beef was formed into either hand- or machine-made patties using a Tupperware patty forming ring or a Hollymatic Patty Machine, respectively. Handmade patties were placed in sealed plastic bags and stored overnight at 23C until cooked. Machine-made patties were placed in stacks of 8}10 with patty liners between each patty, sealed in plastic bags, boxed and held at !103C for less than one week until they were cooked directly from the frozen state. The hand-made patties were approximately 9 cm in diameter, 1.5 cm in thickness and weighed 115 g, while machine-made patties averaged 11 cm in diameter, 1.2 cm in thickness and weighed 117 g. Cooking Procedure The cooking methods used were: microwaving, microwave reheating, broiling, panfrying, and baking. Patties were cooked to either medium or well-done for all cooking methods except microwave reheating. Reheating was only performed for pan-fried and broiled patties. To determine the optimum degree of doneness, preliminary cooking trials were conducted for each fat level and cooking method. Patties were evaluated by appearance (a color photograph chart was used to estimate degree of doneness), then adjustments were made in cooking times until a medium or well-done patty was obtained. (It should be noted that cooking end point before consumption should be checked with a thermometer rather than appearance.) For each fat level and cooking method, the cooking time varied (Table 1). Cooking procedures followed American
255
CHARACTERISTICS OF LOW-FAT GROUND BEEF PATTIES TABLE 1
Cooking times of fresh, hand-made and frozen, machine-made ground beef patties, varying in fat level, cooking method, and degree of doneness Fat level Cooking method Microwave Fresh Medium Well-done Frozen Medium Well-done Broil Fresh Medium Well-done Frozen Medium Well-done Pan-fry Fresh Medium Well-done Frozen Medium Well-done Bake Fresh Medium Well-done Frozen Medium Well-done
5%
10%
15%
1.20, 1.15 1.35, 1.35
1.15, 1.15 1.20, 1.20
1.10, 1.10 1.25, 1.25
1.20, 1.20 1.35, 1.35
1.15, 1.15 1.20, 1.20
1.15, 1.15 1.25, 1.25
8.00, 7.30 10.00, 9.30
7.00, 7.00 9.00, 9.00
5.00, 4.30 1.25, 1.25
6.30, 6.30 8.00, 8.00
6.30, 6.00 7.30, 7.30
6.00, 5.30 7.00, 7.00
4.00, 4.00 5.30, 5.30
4.00, 3.30 5.30, 5.00
3.30, 3.30 5.00, 5.00
4.00, 4.00 5.00, 5.00
4.00, 4.00 5.00, 4.30
3.30, 3.30 5.00, 4.30
25.00 28.00
21.00 25.00
19.00 23.00
24.00 27.00
23.00 25.00
22.00 25.00
Cooking times are recorded in minutes per side. Patties were turned once. Microwave reheating time for fresh broiled and pan-fried patties was 1.15 min defrost and 0.5 min reheat. Microwave reheating time for frozen broiled and pan-fried patties was 1.00 min defrost and 1.00 min reheat.
Meat Science Association (1978) guidelines when applicable. Listed are descriptions of the cooking methods: (a) Microwaving: Patties were cooked separately on a pre-heated browning dish in a Kenmore microwave oven (power consumption: 1580 W) using the high-power setting. (b) Microwave reheating: Previously broiled and pan-fried patties were packaged in plastic wrap and aluminum foil and stored in the freezer at !103C. Frozen patties were then placed on a plate in a microwave oven (same as above) to be defrosted and heated at the high-power setting. (c) Broiling: Two patties were cooked simultaneously on a pre-heated electric Farberware Open-Hearth Broiler.
256
KIRCHNER E¹ A¸. TABLE 2
Fat content (g per cooked patty) means (S.D.) for cooking method, degree of doneness, and patty form Fat level Treatment parameter Cooking method Microwave (n"24) Broil (n"24) Broil/reheat (n"24) Pan-fry (n"24) Pan-fry/reheat (n"24) Bake (n"24) Degree of doneness Medium (n"72) Well-done (n"72) Patty form Fresh, hand-made (n"72) Frozen, machine-made (n"72) 1,2,3
5%
10%
15%
6.3 (0.52) 6.7 (0.62) 6.8 (0.53) 6.9 (0.57) 6.4 (0.41) 6.8 (0.52)
9.6 (1.42) 11.3 (1.39) 10.4 (1.32) 11.1 (0.90) 10.2 (1.44) 11.2 (1.17)
11.8 (1.80) 14.1 (2.06) 12.6 (1.79) 13.6 (1.55) 12.5 (1.21) 13.9 (1.52)
6.7 (0.57) 6.5 (0.55)
10.7 (1.44) 10.5 (1.37)
13.4 (1.99) 12.8 (1.66)
6.3 (0.48) 6.9 (0.46)
9.8 (1.17) 11.5 (1.04)
11.8 (1.21) 14.4 (1.36)
Means within a treatment parameter and column having di!erent superscripts are di!erent (P(0.05).
(d) Pan-frying: Patties were placed individually in a pre-heated West Bend electric skillet at 1633C. A spot check surface thermometer was used to calibrate the skillet. (e) Baking: Two patties were put on a wire rack with a cookie sheet underneath and placed in an oven pre-heated to 1773C. For all cooking methods, juices were allowed to drain from the patties. Broiled and baked patties were cooked on wire racks, which allowed drip loss to occur during cooking. Pan-fried and microwaved patties were drained after cooking by tilting the patty with a spatula and permitting fat to drain. Weights of the raw, cooked, and reheated patties were recorded, and the patty was then minced in a Cuisinart food processor. Portions of each sample were placed in air-tight polypropylene amber vials and frozen at !103C for subsequent chemical analyses. Determination of Fat Content A modi"ed Folch et al. (1957) method of total lipid extraction was performed. A 5 g sample was homogenized with 75 mL of chloroform : methanol (2 : 1) for 3 min using a Virtis homogenizer. The homogenate was "ltered through Whatman No. 42 "lter paper with slight suction. The meat residue and "lter paper were rehomogenized for 3 min with 5 mL of chloroform : methanol (2 : 1) and then "ltered into the same Erlenmeyer #ask using new "lter paper. The combined "ltrate was transferred to
257
CHARACTERISTICS OF LOW-FAT GROUND BEEF PATTIES TABLE 3
Protein content (g per cooked patty) means (S.D.) for cooking method, degree of doneness, and patty form Fat level Treatment parameter Cooking method Microwave (n"24) Broil (n"24) Broil/reheat (n"24) Pan-fry (n"24) Pan-fry/reheat (n"24) Bake (n"24) Degree of doneness Medium (n"72) Well-done (n"72) Patty form Fresh, hand-made (n"72) Frozen, machine-made (n"72) 1,2,3
5%
10%
15%
26.0 (0.63) 25.31}3 (1.28) 25.21}3 (1.46) 25.0 (1.32) 24.5 (0.72) 25.5 (1.18)
22.2 (0.92) 22.2 (1.00) 21.3 (1.64) 21.9 (0.91) 21.8 (1.07) 22.3 (1.26)
21.1 (0.92) 20.8 (1.03) 20.8 (1.36) 21.2 (1.46) 20.5 (1.13) 20.6 (0.90)
25.3 (1.33) 25.2 (1.09)
21.8 (1.08) 22.1 (1.29)
20.8 (1.14) 20.9 (1.20)
24.9 (1.06) 25.6 (1.26)
21.9 (1.38) 22.0 (0.98)
20.7 (1.13) 21.0 (1.20)
Means within a treatment parameter and column having di!erent superscripts are di!erent (P(0.05).
a 500 mL separatory funnel, 25 mL distilled water was added and the phases were allowed to separate. The lower phase in the funnel (organic phase) was drained from the funnel into a 100 mL volumetric #ask. The organic phase was brought to 100 mL volume with pure chloroform. Any aqueous phase was removed, and the volume was again brought to 100 mL using pure chloroform. The contents were transferred into large Te#on-coated, screw-cap test tubes, capped with nitrogen, and stored at !103C until analyzed. Total lipid analysis for each patty was determined in triplicate using 10 mL of extract. The solvent was evaporated at room temperature in the fume hood, and the samples were dried at 1003C for 1 h. The mean patty fat content was computed by averaging the triplicates. Determination of Cholesterol, Protein and Moisture Content Cholesterol content for each patty was determined in triplicate using the procedure of Bohac et al. (1988). The mean patty cholesterol content was computed by averaging the triplicates. Protein for each patty was determined in triplicate using an AOAC (1990) approved Kjedahl block digestion method. The mean patty protein content was computed by averaging the triplicates. Moisture content of each patty was measured using an AOAC (1990) oven-drying procedure.
258
KIRCHNER E¹ A¸. TABLE 4
Moisture content (g per cooked patty) means (S.D.) for cooking method, degree of doneness, and patty form Fat level Treatment parameter Cooking method Microwave (n"24) Broil (n"24) Broil/reheat (n"24) Pan-fry (n"24) Pan-fry/reheat (n"24) Bake (n"24) Degree of doneness Medium (n"72) Well-done (n"72) Patty form Fresh, hand-made (n"72) Frozen, machine-made (n"72)
5%
10%
15%
54.5 (3.77) 52.9 (5.31) 44.4 (6.92) 58.8 (4.59) 51.0 (3.43) 57.0 (2.71)
49.6 (2.70) 49.9 (4.62) 41.4 (4.49) 53.6 (4.40) 46.6 (5.24) 57.6 (2.92)
46.1 (2.54) 49.8 (6.30) 41.0 (5.54) 50.5 (5.10) 43.1 (4.29) 51.7 (2.92)
55.7 (5.49) 50.5 (6.46)
52.1 (6.25) 47.5 (6.08)
49.8 (5.30) 44.2 (5.48)
53.4 (7.48) 52.8 (5.44)
50.9 (6.61) 48.7 (6.36)
49.2 (5.50) 44.8 (5.83)
1,2,3,4,5 Means within a treatment parameter and column having di!erent superscripts are di!erent (P(0.05).
Cooking >ields and Fat Retention Percentage cooking yields and fat retention were determined for each sample using raw versus cooked data as described by Jones et al. (1992) and Murphy et al. (1975). The equations follow: Cooking yield (%)"(cooked weight)/(raw weight);100, Fat retention (%)"(% fat in cooked lean)/(% fat in raw lean);% cooking yield. Statistical Analyses Analysis of variance was applied to these data to determine signi"cant treatment e!ects. When P(0.05 di!erences were found, Student}Newman}Keuls procedure was used to determine di!erences between means within a fat percentage. These analyses were performed for cooking methods, degree of doneness and patty state for fat, protein, moisture, cholesterol, fat retention, cooking yield, and energy content (SAS, 1988).
259
CHARACTERISTICS OF LOW-FAT GROUND BEEF PATTIES
TABLE 5 Cholesterol content (mg per cooked patty) means (S.D.) for cooking method, degree of doneness, and patty form Fat level Treatment parameter Cooking method Microwave (n"24) Broil (n"24) Broil/reheat (n"24) Pan-fry (n"24) Pan-fry/reheat (n"24) Bake (n"24) Degree of doneness Medium (n"72) Well-done (n"72) Patty form Fresh, hand-made (n"72) Frozen, machine-made (n"72)
5%
10%
15%
68.7 (7.51) 65.9 (10.38) 66.5 (11.05) 68.6 (9.48) 69.0 (6.97) 64.8 (9.16)
69.0 (6.78) 69.4 (8.57) 67.5 (10.47) 75.0 (9.33) 67.2 (10.26) 73.5 (10.15)
67.9 (7.61) 68.4 (9.98) 68.4 (7.50) 69.9 (10.34) 63.4 (8.93) 71.6 (5.32)
68.2 (9.10) 66.3 (9.24)
70.6 (10.09) 69.9 (9.25)
69.2 (9.31) 67.3 (7.95)
66.5 (8.46) 68.0 (9.86)
69.8 (10.24) 70.7 (9.08)
67.8 (7.63) 68.7 (9.65)
Means within a treatment parameter and column having di!erent superscripts are di!erent (P(0.05).
RESULTS AND DISCUSSION Means values of fat expressed as grams per patty for fresh and frozen ground beef varying in fat level, cooking method, degree of doneness and patty form are shown in Table 2. Evaluating signi"cant di!erences by patty rather than by weight is more appropriate because that is how the patty will be consumed. Patties cooked from the frozen state were higher in fat for each cooking method; the di!erential between fresh and frozen patties appeared to be the greatest at the 15% level. These di!erences may be accounted for by initial di!erences in size and density seen between raw (fresh and frozen) patties. Frozen, machine-made patties developed an outer surface skin that may have retained fat during cooking. This, in combination with the theory that a denser machine-made patty may allow less fat to be lost during cooking, may explain the di!erences between compact frozen machine-made patties and fresh hand-made patties. Within each fat level treatment, microwaved patties tended to have less fat than patties from the other cooking methods. As expected, the values for protein content (Table 3) decreased as initial fat level increased. Values within a fat level were similar, and protein content remained relatively constant among cooking methods and between degrees of doneness. Moisture content (Table 4) showed wide variability among and between treatments due to how the patties were made, what degree of doneness they were cooked to, and the cooking method employed, especially those methods where reheating was used.
260
KIRCHNER E¹ A¸. TABLE 6 Percentage cooking yield means (S.D.) for cooking method, degree of doneness, and patty form Fat level
Treatment parameter Cooking method Microwave (n"24) Broil (n"24) Broil/reheat (n"24) Pan-fry (n"24) Pan-fry/reheat (n"24) Bake (n"24) Degree of doneness Medium (n"72) Well-done (n"72) Patty form Fresh, hand-made (n"72) Frozen, machine-made (n"72)
5%
10%
15%
74.8 (3.54) 73.6 (4.99) 65.2 (4.59) 78.8 (4.60) 71.5 (3.39) 77.2 (3.16)
73.7 (3.14) 72.7 (4.74) 64.4 (4.88) 85.5 (4.02) 78.4 (4.64) 79.4 (2.79)
69.2 (3.44) 74.9 (6.49) 65.3 (3.66) 75.0 (5.07) 66.8 (3.00) 75.6 (3.77)
75.6 (5.33) 71.5 (5.93)
74.2 (6.21) 70.0 (5.72)
73.7 (5.68) 68.5 (5.21)
74.3 (6.79) 72.8 (4.96)
72.6 (6.81) 71.6 (5.78)
71.9 (5.93) 70.3 (6.07)
1,2,3,4,5 Means within a treatment parameter and column having di!erent superscripts are di!erent (P(0.05).
TABLE 7 Percentage fat retention means (S.D.) for patty form (fresh, hand-made or frozen, machine-made) Fat level Treatment parameter Patty form Fresh, hand-made (n"72) Frozen, machine-made (n"72)
5%
10%
15%
94.5 (7.19) 94.3 (8.93)
77.9 (9.36) 85.5 (7.72)
67.9 (6.98) 108.3 (10.25)
Means within columns having di!erent superscripts are di!erent (P(0.05).
Absolute moisture content values on a per patty basis ranged about 10% points from the highest to the lowest values. It is important to understand the interrelationships of these factors on moisture content because of its relationship to the ultimate eating qualities of the cooked patty. Attempts should be made to use cooking methods that maintain higher levels of moisture to ensure adequate patty juiciness. Cholesterol content of fresh and frozen raw patties was not related to the initial fat level (Table 5), and there were no consistent trends among cooking methods within or across fat levels. This "nding concurs with previous research that found no
261
CHARACTERISTICS OF LOW-FAT GROUND BEEF PATTIES TABLE 8
Percentage fat retention mean (S.D.) for cooking method and degree of doneness of frozen, machine-made patties Fat level Treatment Cooking method Microwave (n"12) Broil (n"12) Broil/reheat (n"12) Pan-fry (n"12) Pan-fry/reheat (n"12) Bake (n"12) Degree of doneness Medium (n"36) Well-done (n"36)
5%
10%
15%
92.0 (3.19) 97.1 (4.68) 91.3 (5.40) 96.1 (7.88) 88.9 (5.27) 96.3 (4.70)
78.3 (6.12) 91.7 (5.60) 84.3 (6.07) 87.4 (4.49) 83.0 (9.60) 88.7 (6.79)
99.8 (5.71) 117.9 (12.33) 104.0 (7.96) 111.4 (7.46) 104.0 (8.60) 112.0 (7.64)
94.3 (5.81) 92.9 (6.22)
86.9 (7.85) 84.3 (7.49)
111.6 (10.81) 104.9 (8.55)
1,2,3 Means within a treatment parameter and column having di!erent superscripts are di!erent (P(0.05).
TABLE 9 Percentage fat retention mean (S.D.) for cooking method and degree of doneness of fresh, hand-made patties Fat level Treatment parameter Cooking method Microwave (n"12) Broil (n"12) Broil/reheat (n"12) Pan-fry (n"12) Pan-fry/reheat (n"12) Bake (n"12) Degree of doneness Medium (n"36) Well-done (n"36)
5%
10%
15%
87.8 (3.96) 92.2 (6.39) 97.8 (5.07) 99.5 (7.30) 92.9 (5.77) 96.8 (7.90)
69.1 (9.54) 81.4 (7.67) 76.0 (8.37) 83.7 (5.81) 73.8 (8.82) 83.2 (6.85)
59.4 (6.63) 72.6 (5.89) 64.0 (4.13) 70.8 (3.51) 66.9 (4.03) 73.4 (5.17)
95.5 (7.31) 93.5 (7.04)
78.1 (9.35) 77.6 (9.49)
68.6 (6.68) 67.1 (7.29)
1,2,3,4 Means within a treatment parameter and column having di!erent superscripts are di!erent (P(0.05).
262
KIRCHNER E¹ A¸. TABLE 10
Energy content (kJ per cooked patty) means (S.D.) for cooking method, degree of doneness, and patty form Fat level Treatment parameter Cooking method Microwave (n"12) Broil (n"24) Broil/reheat (n"24) Pan-fry (n"24) Pan-fry/reheat (n"24) Bake (n"24) Degree of doneness Medium (n"72) Well-done (n"72) Patty form Fresh, hand-made (n"72) Frozen, machine-made (n"72)
5%
10%
15%
601 (15.0) 602 (29.8) 592 (26.1) 604 (23.6) 580 (19.4) 609 (27.7)
654 (50.2) 709 (43.9) 667 (47.8) 701 (33.7) 665 (40.2) 708 (40.4)
712 (65.1) 786 (70.5) 732 (73.8) 773 (57.6) 726 (38.5) 774 (53.5)
598 (25.4) 598 (25.9)
686 (50.0) 682 (48.2)
759 (68.2) 742 (63.2)
594 (23.9) 602 (26.7)
661 (49.6) 707 (36.0)
708 (45.8) 793 (55.6)
1,2,3 Means within a treatment parameter and column having di!erent superscripts are di!erent (P(0.05).
signi"cant relationship between fat level and cholesterol content (Hoelscher et al., 1987). Whether the patty was fresh or frozen had no signi"cant bearing on cholesterol content. Mean values for percentage cooking yield are shown in Table 6. Cooking yield varied little as fat percentage increased. This was due to more fat being lost at the 15% fat level, and more moisture lost at the 5% fat level, thus equalizing values. Well-done patties, as would be expected, had a lower cooking yield than patties cooked to a medium degree of doneness. Cooking yield was lowest for broiled/reheated patties. There was a signi"cant interaction between fat level and patty form (Table 7). As fat level increased, the magnitude of the di!erence between fresh, hand-made and frozen, machine-made increased substantially. Thus, data were analyzed separately for each patty form treatment and are reported in Tables 8 & 9. For frozen patties (Table 8), those microwaved, broiled/reheated, and pan-fried/reheated retained less fat than the other patties evaluated. Fresh, hand-made patties showed no consistent trends within fat levels (Table 9). Cooking retentions were the highest (and in some cases exceeded 100%) for the 15% fat level treatment. Degree of doneness had little or no e!ect on fat retention, regardless of whether the patties were cooked from the fresh or frozen state. In contrast to the "ndings reported in Table 8, fat retention was considerably lower for the 15% fat level treatment. For comparisons of energy content, microwaved and reheated patties contained statistically less energy (but with no practical signi"cance) than other cooking
CHARACTERISTICS OF LOW-FAT GROUND BEEF PATTIES
263
methods (Table 10). Cooking to medium or well-done had no e!ect on energy value because moisture content (no nutritive value) was the only proximate analysis a!ected by doneness. With increasing fat content levels, those patties that were frozen, machine-made had higher energy content than those that were fresh, hand-made. This was due primarily to the fat retention di!erences discussed previously. Sheard et al. (1998) found that burgers from the fattest categories they studied lost about 30% of the energy upon cooking; however, the low-fat burgers, when fried in vegetable oil, increased in energy.
CONCLUSIONS The primary objective of this study was to provide nutrient data for low-fat ground beef using preparation methods practiced by today's consumer. These data will aid consumers, dietitians, and scientists by providing nutrient values and trends for a comprehensive list of cooking methods using fresh, hand-made and frozen, machine-made patties. Even though di!erences in energy content were statistically signi"cant between fresh and frozen patties, the average di!erence was minimal. For most consumers, this reduction is insigni"cant. Microwaving and reheating patties also resulted in reduced energy, but again the di!erences would likely be insigni"cant to consumers. For ground beef containing 5}15% fat, fat and energy content varied little between cooking methods. Individuals watching fat and caloric intake would bene"t from the knowledge that they could choose 5}15% fat ground beef and use a variety of cooking methods, whereas a consumer choosing higher-fat ground beef is limited to certain cooking methods if they wish to reduce the amount of fat and energy they consume. No consistent trends in cholesterol content were found between fat levels, cooking methods, degrees of doneness or patty states. This information will allow those individuals concerned about cholesterol intake to be less restricted in their diet without increasing dietary cholesterol.
REFERENCES American Meat Science Association (1978). Guidelines for Cookery and Sensory Evaluation of Meat. National Live Stock and Meat Board, Chicago, IL. AOAC (1990). O.cial Methods of Analysis, 15 edn. Association of O$cial Analytical Chemists, Washington, DC. Bohac, C. E., Rhee, K. S., Cross, H. R., and Ono, K. (1988). Assessment of methodologies for colorimetric cholesterol assay of meats. J. Food Sci. 53, 1642}1644. Council for Agricultural Science and Technology (1985). Diet and coronary heart disease. Report No. 107. United States Department of Agriculture, Washington, DC. Folch, J., Lees, M., and Stanley, G. H. S. (1957). A simple method for isolation and puri"cation of lipids from animal tissues. J. Biol. Chem. 226, 497}509. Hoelscher, L. M., Savell, J. W., Harris, J. M., Cross, H. R., and Rhee, K. S. (1987). E!ect of initial fat level and cooking method on cholesterol content caloric value of ground beef patties. J. Food Sci. 52, 883}885. Jones, D. K., Savell, J. W., and Cross, H. R. (1992). E!ects of fat trim on the composition of beef retail cuts * 3. Cooking yields and fat retention of the separable lean. J. Muscle Foods 3, 73}81. Murphy, E. W., Criner, P. E., and Gray, B. C. (1975). Comparisons of methods for calculating retentions of nutrients in cooked foods. J. Agric. Food Chem. 23, 1153}1157. Pearson, A. M., and Tauber, F. W. (1984). Processed Meats, 2nd edn. Van Nostrand Reinhold Co., New York, NY. SAS (1988). SAS ;sers Guide: Statistics. SAS Institute, Cary, NC.
264
KIRCHNER E¹ A¸.
Savell, J. W., Cross, H. R., Francis, J. J., Wise, J. W., Hale, D. S., Wilkes, D. L., and Smith, G. C. (1989). National Consumer Retail Beef Study: Interaction of trim level, price and grade on consumer acceptance of beef steaks and roasts. J. Food Qual. 12, 251}274. Savell, J. W., Harris, J. J., Cross, H. R., Hale, D. S., and Beasley, L. C. (1991). National Beef Market Basket Survey. J. Anim. Sci. 69, 2883}2893. Sheard, P. R., Nute, G. R., and Chappell, A. G. (1998). The e!ect of cooking on the chemical composition of meat products with special reference to fat loss. Meat Sci. 49, 175}191. USDA (1990). Composition of Foods: Beef Products: Raw, Processed, and Prepared. Agriculture Handbook No. 8-13. United States Department of Agriculture, Washington, DC. USDA (1996). Institutional Meat Purchase Speci,cations for Fresh Beef Products: Series 100. Agricultural Marketing Service, United States Department of Agriculture, Washington, DC.