RELATIONSHIPS AMONG CHEMICAL, COOKING AND COLOR PROPERTIES OF BEEF PATTIES COOKED TO FOUR INTERNAL TEMPERATURES

A study involving five laboratories and nationwide sampling of ground beef was undertaken to determine cooking and color properties of patties cooked to 52.7, 65.6, 71.1 and 79.4C. The design of the study included purchase location (local, distant) and patty handling prior to cooking Pesh, thawed either as patties or bulk ground beef). Purchase location was not a statistically significant influence on cooking and color properties. Patties processed from bulk thawed product had a higher amount of brown cooked color. A strong relationship existed between visual and instrumental measures of red color in cooked patties. However, correlations among other cooking properties were low. Patties with higher fat content were associated with shorter cooking times, lower cooking yields and more brown cooked color. The low relationships between raw and cooked patty properties limits the use of raw ground beef properties as predictors of food safety in cooked beef patties. This further supports the use of instant read meat thermometers in cooking beef patties to at least 71C.     

CHEMICAL PROPERTIES OF GROUND BEEF PATTIES EXHIBITING NORMAL AND PREMATURE BROWN INTERNAL COOKED COLOR

Premature browning is a condition in which ground beef looks well-done at lower than expected temperatures. To study this color pattern, chemical properties were measured on raw and cooked patties (55, 65 and 75C) that developed normal (NRM) and premature brown (PMB) color when cooked to 55C. NRM patties were visually and instrumentally redder at all temperatures (P<0.05) than PMB patties. Visual color of PMB patties at 55C and NRM patties at 75C were similar (P>0.05). Heme and nonheme iron, total pigment and pH did not differ (P>0.05) between groups. Nonheme iron increased (P<0.05) as endpoint temperature increased. Patties with NRM color had lower (P<0.05) TBA values and oxidative-reduction potentials and higher (P<0.05) total reducing activity than patties with PMB. No difference (P>0.05) occurred in precipitation of juice extracts from NRM and PMB patties during heating (40 to 75C). Premature browning was related to patty oxidation.     

FACTORS AFFECTING COLOR PROPERTIES OF BEEF PATTIES COOKED ON AN OUTDOOR GAS GRILL

Visual and instrumental color properties were obtained on beef patties cooked on an outdoor gas grill. Factors evaluated as to their influence on color were fat content, (20–28% vs 6–10%) patty handling prior to cooking (fresh, thawed either as patties or bulk ground beef), endpoint in cooking (57, 66, 71C, slit in outer edge of patty during cooking showing brown color), lighting conditions and evaluation time post-cooking. Factors resulting in less pink/red color and more brown color in cooked patties were (1) higher fat content, (2) cooking bulk frozen, thawed, then pattied product, (3) higher endpoint temperature and longer time postcooking before evaluation. Termination of cooking by observing brown color in slits in patties cooked on a gas grill was not synonymous with a safe internal temperature.     

COOKED COLOR OF PATTIES PROCESSED FROM VARIOUS COMBINATIONS OF NORMAL OR HIGH pH BEEF AND LEAN FINELY TEXTURED BEEF

Color of cooked patties prepared from beef with a pH of 5.7 (normal = N) or pH = 6.2 (dark cutting = DC) beef and with either 0, 25, 50 or 75% lean finely textured beef (LFTB) was evaluated. Patties were cooked to 68.3C, 71C, or until >75% were "well-done". Inclusion of LFTB in N patties resulted in higher a*-values, but did not affect either visual color scores or myoglobin (Mb) denaturation. Inclusion of LFTB in DC patties did not affect pH. A higher LFTB content resulted in lower a*-values, higher hue-angle, a more well-done visual color and increased Mb denaturation. To appear well-done, DC patties without LFTB had to be cooked to 89C, whereas DC patties with 75% LFTB had to be cooked to 83C. Possibly, conditions during production of LFTB are responsible for the increased heat sensitivity of Mb from LFTB.     

PATTY FORMATION METHOD, THICKNESS AND WEIGHT EFFECTS ON PROPERTIES OF COOKED LOW-FAT BEEF PATTIES

Effects of patty thickness (0.95 and 1.27 cm), weight (90 and 113 g) and type of patty fill method (traditional gravity fill = FF and twisted through holes into mold = TF) were evaluated using low-fat (10%) ground beef. An increase in patty thickness from 0.95 cm to 1.27 cm, resulted in a decreased (P<0.01) sensory firmness and peak load (Newtons) and increased (P<0.01) initial juiciness. TF fill method and 1.27 cm thick FF treatments improved tenderness and juiciness over 0.95 cm thick FF patties. This study revealed that improvements in tenderness and juiciness of low-fat beef patties can be attained through use of appropriate patty formation procedures.     

INSTRUMENTAL MULTIPLE TEXTURE PROFILE ANALYSIS OF COOKED GROUND BEEF PATTIES AND SMOKED BEEF

An instrumental texture profile for cooked hamburger patties was obtained by repeated tests on the same samples in the wire extrusion cell of the Ottawa Texture Measuring System. The correlation between sensory and instrumental texture profile parameters was increased when two or more instrument test cycles were applied to each sample in the same test cell. Tests with smoked beef and hamburger patties showed that the change in textural characteristics with repeated cycles depended on the texture of the food.     

EFFECTS OF SOY PARTICLE SIZE AND COLOR ON THE SENSORY PROPERTIES OF GROUND BEEF PATTIES

A study was conducted to assess the effect of both size and color of textured soy protein particles on the visual and textural properties of extended (20% replacement) ground beef patties. A trained texture profile panel judged the hardness, cohesiveness, chewiness, moistness, and oiliness of nine different samples. In addition, judgments of the visual attributes of darkness, size of particles, and density of particles were made. Significant effects of soy ingredient were found for all judged attributes. It was concluded that soy ingredients having particle sizes smaller than the diameter of the openings of the grind plate used to process the meat/soy mixture produced the greatest change in the texture of the ground beef patties, because these particles passed through the grind plate unscathed, producing an easily discernable matrix of large meat particles and small soy particles. It was also concluded that carmel-colored soy ingredients produced less lightening of the cooked samples than uncolored soy ingredients.     

FUNCTIONAL PROPERTIES OF SORGHUM FLOUR AS AN EXTENDER IN GROUND BEEF PATTIES 1

Patties were formulated with 20% fat ground beef and sorghum flour (SF) at 2, 4, and 6% levels (10, 20, and 30% as rehydrated 1:4 with water). Beef patties containing SF had higher pH, greater yield, less total cooking loss, less shrinkage in diameter, and less increase in thickness than those without SF. Water activity of cooked patties was not affected by addition of SF. Fat and water retentions of beef patties increased as the level of SF increased. Hunterlab a values (redness) for raw patties decreased as the level of SF increased, but a values for cooked patties were not influenced by level of SF. Shear force and compression of cooked patties decreased as the level of SF increased. Meat aroma and flavor decreased, but sorghum aroma and flavor of cooked patties increased as the level of SF increased. Tenderness of cooked patties increased as the level of SF increased, but juiciness of cooked patties was not affected.     

RELATIONSHIP OF USDA MARBLING GROUPS TO PALATABILITY OF COOKED BEEF

As marbling increased from“practically devoid” to“moderately abundant”, loin steaks were more palatable (P<0.05) about 2/3 of the time, round steaks were more palatable (P<0.05) about 1/8 of the time, and loin steaks were more likely to be assigned high (≥6.00) panel ratings and to have low (≤3.63 kg) shear values. However, increases in marbling from“slight” to“moderately abundant” (A maturity) and from“small” to“moderately abundant” (A+B maturity) had little or no efect on percentage incidence of loin or round steaks with panel ratings ≤2.99 or ≥4.00, or with shear values ≥6.35 kg or ≤4.99 kg. Differences in marbling explained about 33% (loin) and 7% (top round) of the variation in overall palatability ratings in A, B, C, and A+B maturity carcasses.     

CHANGES IN TENDERNESS OF BEEF LONGISSIMUS DORSI AS RELATED TO MUSCLE COLOR AND pH

Longissimus dorsi shear values for carcasses of 168 steers, 147 heifers and 259 bulls, all slaughtered in the age range of 12–16 months, were correlated with postmortem pH values and postmortem change in pH. Neither the individual pH values nor degree of postmortem pH change were useful predictors of shear value for steer and heifer carcass (r² values less than 0.07). For bull carcasses, pH of the longissimus dorsi taken 24 hr postmortem was significantly correlated with shear value, (r =−0.7) and with meat color (r =+0.7). Sexes differed markedly in the range of 24 hr pH of the longissimus dorsi with none of the steers, 8% of the heifers and 49% of the bulls having values greater than 6.0.     

EFFECTS OF COOKING AND SUBSEQUENT REHEATING ON THE PROPERTIES OF LOW-FAT BEEF PATTIES

Low-fat (10%) beef patties manufactured with 0.5% iota carrageenan, were subjected to one-time cooking from the raw to fully cooked state or precooking and later reheating before evaluating sensory, shear force and cooking properties. The samples were reheated in a convection oven or in a simultaneous top and bottom contact grill set either at 121 or 191C. Precooking followed by reheating produced only slight changes in sensory properties (reduced tenderness, increased juiciness and increased beef flavor). Convection oven cooking improved tenderness only for one-time cooked patties. With the double contact grilling system, the 121C surface temperature enhanced tenderness (sensory and shear force) and cooking yields of precooked-reheated patties. Low-fat beef patties formulated with iota carrageenan appear capable of being subjected to a variety of cooking approaches and temperatures without major changes in cooked patty properties.     

RELATIONSHIP OF USDA QUALITY GRADES TO PALATABILITY OF COOKED BEEF1

Prime carcasses produced loin and round steaks that were more palatable (P < 0.05) than were those from carcasses of Choice through Canner (7 grades) in 85.7% of comparisons and from carcasses of Choice through Standard (3 grades) in 69.0% of comparisons; comparable percentages were 71.4% (6 grades) and 42.9% (2 grades) for Choice and 74.3% (5 grades) and 35.7% (1 grade) for Good. Among Prime through Standard carcasses, grade predicted flavor, tenderness and overall palatability of loin steaks with 30 to 38% accuracy, but could explain no more than 8% of the variation in panel ratings/shear force values of round steaks.     

USE OF DIGITALIZED IMAGES TO VISUALLY ASSESS COLOR OF COOKED SAUSAGES

A study was undertaken to explore the use of computer imaging to assess the color of cured meat products. Wiener sausages were manufactured to produce a color gradient. Increasing amounts of red carmine were added to the raw sausage emulsion (0, 50, 65, 100, 125, and 150 ppm) so that the extreme shades (0 and 150 ppm carmine) were clearly different, while the smallest color difference (e.g. 50 and 65 ppm carmine) was barely perceptible. Slices of the sausages containing 0, SO, 100, 125, atzd 15O ppm of carmine were presented to a group of 10 trained panelists in a standard lightbooth (065 lighting, 978 ± 21 lux; ASTM 1996) and the panelists were asked to evaluate the relarive color difference between each sausage and a reference sausage (65 ppm carmine), using the standard R-index multiple comparison test. The panelists were also asked to make the same evaluation while looking at digitalized images of the sausage slices on a high quality color computer screen. In general, small differences in shade (Δa* 1.0–1.8) were more ofen perceived by panelists when these were looking at slice images on the computer screen than when observing the actual slices in the lightbooth.