Effects of Endpoint Temperature on the Internal Color of Pork Patties of Different Myoglobin Form, Initial Cooking State, and Quality

ABSTRACT: :The effects of several parameters on the development of internal cooked color in ground pork were evaluated. Patties were made from normal or pale, soft, and exudative (PSE) pork and the pigment converted to either oxymyoglobin or deoxymyoglobin. Patties from these 4 treatment combinations were cooked from the frozen or thawed states to 5 endpoint temperatures. PSE patties and those containing oxymyoglobin exhibited premature browning as they appeared cooked and were more (P < 0.05) tan at lower temperatures than normal patties or those with deoxymyoglobin which had a slightly pink internal color at 71 °C. Percentage myoglobin denaturation increased as cooking temperatures increased (P < 0.05) for both types of meat and was greater in patties containing deoxymyoglobin than in those with oxymyoglobin. Patties cooked frozen had lower a* values (P < 0.05) than thawed patties at every endpoint temperature.     

Cooked Color in High pH Beef Patties as Related to Fat Content and Cooking from the Frozen or Thawed State

Beef patties were processed from high pH (>6.0) beef to contain 5, 10, 15, 20 or 25% fat. Patties were cooked to 71°C from the frozen or thawed state before evaluating color. Neither fat content nor state of patties when cooked exerted any major influence on color, but linear effects (p<0.01) in association with increased fat content included higher L* values and hue angles and lower a* values (15.2% reduction). Higher values for L*, b* (but not for 5% fat patties), and hue angles were observed for patties cooked thawed rather than frozen. The use of high pH beef lessened the effects of increased fat and cooking from the thawed state on increased brown color in cooked patties.     

Influence of Cooking Rate, Endpoint Temperature, Post-cook Hold Time, and Myoglobin Redox State on Internal Color Development of Cooked Ground Beef Patties

ABSTRACT: Three experiments investigated cooking rate, endpoint temperature, post-cook holding time, and raw myoglobin redox-state effects on ground beef internal cooked color. In Experiment 1, patties were cooked to endpoint temperatures of 65.6°C, 71.1°C, 76.7°C, 82.2°C, or 87.8°C rapidly (1°C/s), slowly (0.2°C/s), or rapidly with 6-min post-cook holding time at 104°C. Patties cooked slowly to less than 76.7°C were more well done ( P < 0.05) in appearance than those cooked rapidly. Rapidly-cooked patties cooked to less than 82.2°C and held for 6 min after cooking had less pinkness, more myoglobin denaturation, and a more well-done appearance than did rapidly cooked patties with no holding time ( P < 0.05). In Experiment 2, increasing post-cook holding time (1, 3, 6, or 12 min) after rapid cooking to 71.1°C, 76.7°C, or 82.2°C decreased pinkness and increased myoglobin denaturation ( P < 0.05), with no benefit beyond 6 min ( P > 0.05). In Experiment 3, patties cooked rapidly to 71.1°C, 76.7°C, or 82.2°C from a predominantly raw oxymyoglobin state were less pink and had more denatured myoglobin than did those cooked from a predominantly deoxymyoglobin state ( P < 0.05). Prediction equations determined that 80% of myoglobin must be denatured to create a well-done appearance. Using a slow cooking rate, post-cook holding time, or cooking from a highly oxygenated state will increase myoglobin denaturation and foster a well-done appearance.     

EFFECTS OF SOY PROTEIN AND FREEZING TREATMENTS ON COOKING LOSS AND COMPOSITION OF BEEF PATTIES

All-beef and soy-extended patties were frozen to −18°C in either 24, 48, 72 or 96h and stored at −23, −18 or −7°C for 6, 9, 12, 18 or 24 months. The addition of soy resulted in a substantial reduction in cooking loss for patties cooked from the frozen state with a greater retention of moisture in cooked patties. Freezing reduced cooking loss for soy-extended patties, but increased cooking loss for all-beef patties. Faster freezing (-18°C in 24 h vs. −18°C in 96 h) reduced cooking loss and produced higher moisture values in all-beef patties. Patties stored at –7°C lost more moisture during cooking. Increased frozen storage time had a minimal effect on cooking losses, moisture and fat levels. Where it is essential for frozen patties to sustain minimal cooking losses with maximal moisture in cooked patties, the inclusion of soy protein concentrate, faster freezing, and storage at –18°C or colder are suggested.     

Effect of pH and Total Pigment Concentration on the Internal Color of Cooked Ground Beef Patties

pH of ground beef components, from three purveyors, was measured for 150 consecutive days of production. Patties were produced from the components with pH values within the interval 5.6–6.2 and cooked (71°C) on a gas grill (176°C). The internal color of the cooked patties was described by a sensory panel. The internal color varied from grey in patties within the normal pH range (5.3–5.7) of muscle, to slightly red in muscles with a pH of 6.2. Red to pink cooked color was most intense inside those patties with the highest pH and the greatest concentration of total pigments. Bull meat exhibited a much higher pH and a greater level of total pigments than the other components studied. Controlling the pH of bull meat could be important in improving the cooking characteristics and quality of ground patties containing it. Purveyor specifications for bull meat should include pH as a criteria for purchase when cooking time and quality are critical to the customer.     

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.     

Low Fat Level Effects on Sensory, Shear, Cooking, and Chemical Properties of Ground Beef Patties

Two experiments were conducted to determine the effects of targeted fat level (0, 4, 8, 12, 16, 20%) on sensory, shear, cooking and chemical properties of ground beef patties. Frozen patties from all fat levels were cooked to achieve similar cooking yields. As fat levels decreased, tenderness, juiciness and flavor ratings decreased and shear force increased, with more pronounced differences at lower fat levels. Patties processed with 0% fat were rated lower in juiciness and flavor compared to all other fat levels. These studies suggested that alterations in processing and cooking would probably be necessary to achieve acceptance of extremely low-fat beef patties.     

Effect of erythorbate, storage and high-oxygen packaging on premature browning in ground beef

Premature browning (PMB) was investigated in ground beef patties with (0.04%, w/w) and without erythorbate. In Experiment 1, patties were stored at 4 °C for 48 h; at -18 °C for 21 days; or at -18 °C for 21 days, thawed at 4 °C for 24 h; and cooked. Bulk ground beef was stored at -18 °C for 24 days, thawed for 24 h at 4 °C, and patties prepared and cooked immediately. In Experiment 2, fresh patties were overwrapped with oxygen-permeable film or packaged in 80% O(2)/20% N(2) (MAP), and stored for 48 h at 4 °C, or at -18 °C for 21 days, and cooked. Total reducing activity and color (L*, a* and b* values) were measured immediately prior to cooking. Patties were cooked to internal temperatures of 60, 66, 71 and 77 °C and internal cooked color was measured. Total reducing activity was higher for the erythorbate treatment than controls for all storage conditions (P<0.05). a* Values of cooked patties were higher for erythorbate than control treatments under all storage and packaging conditions at 60 and 66 °C (P<0.05). The presence of erythorbate in ground beef patties appeared to maintain red color at cooked internal temperatures of 60 and 66 °C. Frozen bulk storage appeared to increase the susceptibility of ground beef to PMB when compared to fresh and frozen patties. Patties cooked directly from frozen state appeared less susceptible to PMB than frozen-thawed and bulk storage. Ground beef appeared predisposed to PMB when stored in high-oxygen MAP at 4 °C for 48 h.     

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.     

Visual color and doneness indicators and the incidence of premature brown color in beef patties cooked to four end point temperatures

An interlaboratory study was undertaken to assess the frequency that cooked color of ground beef patties appeared brown at internal temperatures of 52.7 degrees C (135 degrees F), 65.6 degrees C (150 degrees F), 71.1 degrees C (160 degrees F), and 79.4 degrees C (175 degrees F). In general, as internal cooked temperature of the patties increased, the following results were observed in the patties: (i) more brown meat color, (ii) less pink or red juice color, and (iii) more cooked texture. However, brown meat color occurred prematurely at the two lower internal temperatures (57.2 degrees C/135 degrees F and 65.6 degrees C/150 degrees F) that are insufficient to eliminate foodborne pathogens without holding times. The common consumer practice of freezing bulk ground beef, followed by overnight thawing in a refrigerator, led to substantial premature brown color in patties cooked from this product. In addition, at 71.1 degrees C (160 degrees F), recognized to be the lowest temperature for cooking ground beef safely in the home, meat color, juice color, and texture appearance were not fully apparent as doneness indicators. In fact, at no temperature studied did 100% of the patties appear done when evaluated by the criteria of no red or pink in the meat, no red or pink in the juices, or by texture appearance. Patties in this study were evaluated under a set protocol for forming the products, cooking, and viewing under the same lighting conditions. Other preparation conditions are possible and may produce different results. Thus, temperature to which patties have been cooked cannot be judged by color and appearance. This study provided the evidence to support the message to consumers regarding cooking of beef patties of "use an accurate food thermometer and cook beef patties to 160 degrees F (71.1 degrees C)" in place of messages based on consumer judgment of cooked color.     

Color and Heat Denaturation of Myoglobin Forms in Ground Beef

To determine the effects of myoglobin forms on internal cooked color in ground beef, patties containing predominantly deoxy-(DMb), oxy-(OMb), or metmyoglobin (MMb) were cooked to 55, 65, or 75 °C. Only patties with DMb appeared red and undercooked at 55 °C, and their color became progressively more brown at 65 and 75 °C. Patties with OMb and MMb were brown at 55 °C and could be mistakenly perceived as being cooked enough to consume. Judging the doneness of ground beef using internal cooked color alone would be valid only if the pigment at time of cooking was predominantly DMb. In model studies, DMb had greater thermal stability than MMb especially at higher pH.     

Fat Level, High Temperature Cooking and Degree of Doneness Affect Sensory, Chemical and Physical Properties of Beef Patties

Ground beef patties containing either 4 or 20% fat were cooked by electric grill (G) alone or in combination with overhead broiler unit (BG) to be (visually) either medium or well-done. Patties with 20% fat had higher beef flavor intensity, juiciness and tenderness scores, lower Instron shear and compression values, and lower cooking yields than 4% fat patties. However, 4% fat patties cooked to medium, had similar sensory ratings to 20% fat patties cooked well-done. About 20% of patties cooked to medium did not reach recommended internal temperatures and holding times for food safety.     

Comparison of Color and Thiobarbituric Acid Values of Cooked Hamburger Patties after Storage of Fresh Beef Chubs in Modified Atmospheres

ABSTRACT: Cooked meat color is an important quality attribute for consumers. This study compared color and thiobarbituric acid (TBA) values of cooked ground beef (internal temperatures of 49 to 79 °C), after storage of raw product in atmospheres of 0.4% carbon monoxide (CO), 80% oxygen, or vacuum at 2 °C for 7 to 21 d. Premature browning, observed as a brown cooked color at internal temperatures as low as 49 °C, was found in patties made from meat stored in 80% oxygen. At all cooking temperatures, samples stored in high oxygen had less internal red color, higher myoglobin denaturation values, and were more rancid with higher TBA values than CO or vacuum-packaged ground beef. Raw ground beef held in 0.4% CO modified-atmosphere packaging (MAP) remained bright red throughout the 21-d storage period. Premature browning and high TBA values in cooked patties were avoided by use of this packaging system. However, internal patty color remained somewhat red even at the highest internal cooking temperature of 79 °C. The persistent pink color observed in CO-treated patties cooked to 79°C internal temperature was likely due to development of heat-denatured CO-hemochrome, rather than the presence of undenatured CO myoglobin. The problems of PMB and high TBA values of cooked patties were also avoided by vacuum packaging. However, the development of dark purple color associated with vacuum packaging of raw beef limits the use of this packaging method for products in retail display. Keywords: beef, packaging, carbon monoxide, oxygen     

Effect of Cooking on Cholesterol Content of Patties Containing Different Amounts of Beef, Textured Soy Protein and Fat

Ground beef patties were prepared to contain 0, 10, 20 or 30% rehydrated textured soy protein (TSP) and 8, 16 or 27% fat. Patties were cooked from the frozen state on a rack in a preheated oven at 177°C to an endpoint internal temperature of 75°C. The cholesterol content of raw ground beef patties decreased as the amount of TSP increased and also decreased as the fat content decreased from 27 to 16 or 8%. At initial fat levels of 8 and 16%, there were no significant differences in cholesterol retention (per-patty basis) during cooking among patties with initial TSP (rehydrated) levels of 0, 10, 20 and 30%; at an initial fat level of 27%, however, patties containing TSP (10, 20 or 30%) retained substantially higher (P < 0.05) amounts of cholesterol when cooked than did those without TSP.     

PROPERTIES OF BEEF PATTIES COOKED TO ELEVATED INTERNAL TEMPERATURES AS A MEANS OF REDUCING PINK COLOR

Effects of cooking to internal temperatures (81–85C) needed to eliminate the pink color which existed at 71C, was evaluated for beef patties from three processors. Tenderness and compositional properties were affected little by the higher temperatures, but lower cooking yields and juiciness scores resulted from cooking to 81–85C rather than 71C. The higher internal temperatures required longer cooking times and produced greater reductions in patty diameter during cooking, but did not affect fat retention. Even though the three formulations were processed to have the same fat content (18%), formulation differences existed in sensory, shear force, cooking, compositional and color properties. Results from this study indicate that if internal patty temperatures higher than 71C are required to eliminate pink color (possibly due to high pH beef), major detrimental changes in patty properties may not result.     

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.     

Microwave Cooking Properties of Ground Pork Patties as Affected by Various Fat Levels

ABSTRACT: Ground pork patties were processed from pork hams to achieve fat levels of 5%, 10%, 15%, 20%, and 25%. Each patty was cooked in a microwave oven to 75 °C from a thawed state. As fat levels increased, cooking time decreased. Total cooking loss and drip loss were highest for 25% fat patties and lowest for 5% fat patties. High-fat patties (20% and 25%) had greater reductions in dia than did 5% to 15% fat patties, but had less change in patty thickness. Shear force values decreased as fat levels increased. Visual evaluations also indicated a greater presence of air pockets in high-fat patties. In raw patties, low-fat samples were darker (had lower L * values) and were redder (had higher a * values) than patties with more fat. However, these differences were relatively smaller when the patties were cooked. As fat levels increased, flavor, tenderness, juiciness, and oiliness ratings increased. These differences were not as apparent when comparing among low-fat patties or high-fat patties. Keyword: microwave, cooking, fat, pork patty     

Final Cooked Temperature Effects of Ground Pork on its Ability to React with Nitrite

ABSTRACT: Fresh ground pork patties from longissimus dorsi muscle were cooked to endpoint temperatures of 54.4 °C, 60.0 °C, 65.6 °C, 71.1 °C, 76.7 °C, or 82.2 °C. After cooking, patties were immersed in a solution of sodium nitrite (125 ppm) and water for 24 h. All patties then were heated again to a final endpoint temperature of 82.2 °C to allow possible formation of nitrosohemochrome. Instrumental color data, spectrophotometric 650/570 nm reflectance ratio, and visual panelists' scores on both exterior and interior surfaces revealed greater redness (pinking) at the lower initial cooked temperature endpoints. Most importantly, this study showed that all patties developed pink color on reheating, regardless of initial endpoint cooked temperature.     

Effect of muscle source on premature browning in ground beef

Premature browning (PMB) describes cooked beef that may appear done before reaching 71 °C. Ground beef from paired Longissimus lumborum (LL) and Psoas major (PM) muscles was formed into patties. Patties were cooked immediately, and after 48 and 96 h storage at 4 °C. Total reducing activity (TRA) and external color were measured immediately prior to cooking. Patties were cooked to internal end point temperatures of 60, 66, 71 or 77 °C and internal cooked color (L(*), a(*) and b(*) values) was measured. Raw PM patties had greater L(*) values and lesser a(*) values than those from LL (P<0.05). For LL and PM, raw a(*) and b(*) values decreased with storage from 0 h to 96 h (P<0.05). At 0 and 48 h storage, cooked patties prepared from PM had greater a(*) values than those prepared from LL at all internal endpoint temperatures (P<0.05). Internal cooked a(*) values of patties from PM decreased with storage of raw patties, whereas it was stable for LL patties (P<0.05).     

EFFECTS of FAT-SUBSTITUTES, FAT LEVELS and COOKING METHODS ON the QUALITY of BEEF PATTIES

Ground beef patties containing 2fat levels (5%, 10%), and 3 fat-substitutes (Lean-Bind (LB), Rice-Complete 3 (RC), Sta-Slim 171 (ST)) were processed using 3 cooking methods (microwave, roasting and pan-frying). Patties containing 20% fat, without fat-substitutes, were processed as a control. Textural properties of cooked patties were evaluated using Kramer shear, puncture, and Texture Profile Analyses. Press-juice, cooking losses and color parameters were also measured. Patties containing ST or LB and 10% fat, cooked by pan-flying, were more tender and juicier than other treatments including control, and had higher product yield than the control. ST provided the lowest cooking losses and the highest press-juice due to strong gelation ability and water holding capacity of ST Fat level did not affect color lightness (L*) or redness (a*) of the patties. However, both fat-substitute and cooking method affected L*, a* and b* (yellowness). Pan frying improved press-juice and reduced cooking losses, thus increased product yield, and provided tender patties compared to microwaved and roasted patties.