Preserving pre-rigor meat functionality for beef patty production

Three methods were examined for preserving pre-rigor meat functionality in beef patties. Hot-boned semimembranosus muscles were processed as follows: (1) pre-rigor ground, salted, patties immediately cooked; (2) pre-rigor ground, salted and stored overnight; (3) pre-rigor injected with brine; and (4) post-rigor ground and salted. Raw patties contained 60% lean beef, 19.7% beef fat trim, 1.7% NaCl, 3.6% starch, and 15% water. Pre-rigor processing occurred at 3-3.5h postmortem. Patties made from pre-rigor ground meat had higher pH values; greater protein solubility; firmer, more cohesive, and chewier texture; and substantially lower cooking losses than the other treatments. Addition of salt was sufficient to reduce the rate and extent of glycolysis. Brine injection of intact pre-rigor muscles resulted in some preservation of the functional properties but not as pronounced as with salt addition to pre-rigor ground meat.     

Structural and palatability relationships in frozen ground beef patties as a function of freezing treatments and product formulation

Four freezing rates for ground beef patties were evaluated for product quality effects and microstructural changes. These rates were further evaluated for different pattie formulations involving post-rigor and pre-rigor meat. Both light microscopy (LM) and scanning electron microscopy (SEM) were utilised for microstructural comparisons. Fast freezing rates had a positive effect on pattie quality, resulting in increased juiciness, tenderness and overall acceptability. Photomicrographs showed increased ice cavity size with decreased freezing rates, which probably contributed to increased cooking shrink and tenderness changes observed. Pre-rigor patties compared very favourably with conventional post-rigor beef patties and showed no obvious structural differences.     

Shortening and tenderness of pre-rigor heated beef: Part 2 - Effect of heating rate on muscles of electrically stimulated carcasses

This study was conducted to compare the effects of rapid and slow heating rates on muscles from electrically stimulated beef carcasses. Myofibrillar and cooking shortening and related changes were measured with physiograph recordings on pre-rigor M. triceps brachii strips suspended in paraffin oil during heating. Warner-Bratzler shear values were determined on pre-rigor and post-rigor M. triceps brachii samples heated at approximately the same rates at which muscle strips were heated (2°C/2 min and 2°C/12 min), on pre-rigor M. triceps brachii samples heated at 2°C/6 min, 2°C/9 min and 2°C/12 min and on pre-rigor and post-rigor M. triceps brachii and M. longissimus muscle heated similarly at 2°C/12 min. Rapid heating (2°C/2 min) of pre-rigor muscle produced more severe myofibrillar shortening that was complete at higher muscle temperature than slow heating (2°C/12 min). Slow heating, in contrast to rapid heating, resulted in a cooked product of lower shear value in both the pre-rigor and post-rigor states. The slower the heating rate of the pre-rigor M. triceps brachii, the more tender was the product. Heating at a rate of 2°C/12 min produced acceptable tenderness in both the pre-rigor M. longissimus and M. triceps brachii muscles but even greater tenderness when both muscles were heated in the post-rigor state. The tenderizing action of severe muscle shortening could not be induced in electrically stimulated muscle.     

Effect of salt on oxidative changes in pre- and post-rigor ground beef

Pre- and post-rigor beef was ground and salt was added to give 0·0, 0·5, 2·0 and 4·0% NaCl (w/w). Samples were removed after 0, 24, 48, 72 and 96 h at 4°C and analyzed for pH, TBA numbers and percentages of reduced myoglobin (Mb), metmyoglobin (MMb) and oxymyoglobin (MbO(2)). After holding for 96 h the samples were cooked in a boiling water bath to an internal temperature of 80°C and held at 4°C for 48 h before TBA analysis. Pre-rigor grinding and salting reduced the post-mortem pH decline and the extent of meat discoloration as shown by the differences in the amount of MMb. The extent of lipid oxidation as measured by TBA numbers was not significantly different for the pre- and post-rigor ground salted meat samples, although salt accelerated oxidation during storage. Results demonstrated that pre-rigor grinding and salting of beef produces a more stable bright red color, which appears to be associated with a lower percentage of MMb and a higher ultimate pH in the pre-rigor salted meat.     

The effects of hot water pasteurizing treatments on the appearances of pork and beef

Portions of post- and pre-rigor pork and beef were treated by immersion in water of 75 or 85 °C for 5, 10, 15 or 20 s. The appearances of untreated and treated cut muscle, fat, membrane covered and cut bone surfaces, and the overall appearances of treated and untreated meat pieces, were assessed by a 5-member panel 2 hr and 24 hr after each treatment. At those times, CIE L(?)a(?)b(?) values were obtained for cut-muscle surfaces. The appearances of surfaces covered by membrane, of fat and cut bone surfaces of pre-rigor pork and beef, and of fat and cut bone surfaces of post-rigor pork, were not persistently degraded by any treatment. However, the appearances of fat and cut bone surfaces of post-rigor beef were persistently degraded by the harsher treatments, apparently because of pre-treatment staining of fat and changes in the bone marrow. Panel scores for the overall appearance and for the appearance of cut muscle surfaces were generally the same for each meat piece. All treatments caused patchy bleaching of cut muscle. The degraded appearances of pre- and post-rigor pork and post-rigor beef muscle persisted at 24 hr, but the appearances of beef muscle treated pre-rigor improved between 2 and 24 hr. Most treated muscle gave increased CIE L(?) values and decreased a(?) and b(?) values as compared with untreated portions from the same primal cut. However, CIE b(?) values for pre-rigor beef muscle were higher than for untreated muscle 2hr after treatment, but lower than for untreated muscle 24 hr after treatment. It appears that pasteurizing treatments cannot be applied to meat without some degradation of the appearances of cut muscle surfaces, which will persist in pork treated pre- or post-rigor and in beef treated post-rigor, but which will partially resolve during the storage of beef treated pre-rigor.     

Effects of brine ingredients and temperature on cook yields and tenderness of pre-rigor processed roast beef

In semimembranosus (SM) muscles removed pre- and post-rigor and injected 10% (wt/wt) with brines formulated to give 2% salt, 1.5% glucose, 0.3% phosphate, 0.15% calcium chloride or 3% sodium lactate in the finished product and cooked within 1 h of injection, cook yields were not significantly affected by processing pre- or post-rigor. Within treatments, however, brine composition had a significant (P < 0.05) effect on cook yields; highest yields were obtained using salt (although this was not significantly different from the water injected control) and lowest yields with calcium chloride. Adding phosphate resulted in lower peak shear force values, and less energy was required to break the sample. The most tender roasts from pre-rigor meat were produced using salt, phosphate or lactate brines and the least tender using calcium chloride. Brine temperature (0-12 °C) during injection had little effect on cook yields or tenderness of the roast beef manufactured pre-rigor. The results indicate that accelerated processing of roast beef can result in finished product with acceptable yields and tenderness if salt and phosphate brines are used.     

Acid phosphatase activity and color changes in consumer-style griddle-cooked ground beef patties

The U.S. Department of Agriculture and the Food and Drug Administration have issued temperature requirements to help consumers cook beef patty products that are free of pathogens. Verification of end-point temperature (EPT) is needed in cooked meat products due to concerns over outbreaks of Escherichia coli O157:H7. Acid phosphatase (ACP) activity was studied as a potential method for determination of EPT in ground beef patties cooked nonfrozen, patties frozen 7 days and thawed at room temperature 4 h in a refrigerator or by microwave, and patties made from ground beef frozen in store packages, then thawed in a refrigerator overnight. Pressed-out meat juices were analyzed from patties (n = 314) cooked to 57.2 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) target EPTs. Expressed meat juice and internal meat patty color decreased in redness as EPT increased. Freezing whole packs with slow refrigerator or room temperature thawing caused significantly greater loss of redness in expressed cooked meat juice than did other handling methods. Log10 ACP had a significant linear (R2 = 0.99) response to EPT. Results show that the 3- to 5-min ACP test could be used to verify EPT in griddle-cooked hamburger patties.     

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 post-slaughter processing and freezing on the functionality of hot-boned meat from young bull

The effects of variation in the times of mincing post mortem (2, 4, or 6 h), pre-rigor salting (1.5% wt wt ) and freezing rate [fast (10 min, liquid nitrogen); medium (4-6 h at -40 °C and 0.8 m s(-1) air velocity); or slow (36-38 h at -10 °C and 0.1 m s(-1) air velocity followed by 12 h at -20 °C and 0.1 m s(-1) air velocity)] on the functionality of young bull meat were examined using hot-boned forequarters. At 52 h post packaging, the meat was thawed (72 h at 4 °C), its pH measured, and it was used to make finely comminuted batters. Cook yield and stress and strain of the cooked batters were measured. Time of mincing had no effect on meat pH, cook yield or stress and strain. There was a significant interaction (P < 0.05) between pre-rigor salting and freezing rate for pH. Freezing rate did not affect the pH of pre-rigor salted meat whereas the pH of unsalted pre-rigor meat was highest at the fastest freezing rate. Meat salted pre-rigor had a significantly (P < 0.05) higher pH than the post-rigor chilled control. Pre-rigor salting decreased the stress values of cooked batter whereas the slowest freezing rate increased stress. Stress and strain values for cooked batters from thawed meat were not significantly different from the values for batters made from the unfrozen control. Cook yields of batters made from pre-rigor frozen meat were higher than that of the postrigor control but not significantly so. The results indicate that suppliers can use pre-rigor salted and frozen meat when manufacturing comminuted products without major detrimental effects on the cook yield and texture of the finished product.     

Effects of carbon dioxide on yield, texture and microstructure of cooked ground beef

The objective of the study was to find the effects of CO(2) gas on cooking loss, instrumental hardness and microstructural changes of ground beef heated to 70-83 °C. In two experiments, ground beef was stored for 4 days in 60% CO(2)/39.6% N(2)/0.4% CO and vacuum (1), or in 100% CO(2), 50% CO(2)/50% N(2), 20% CO(2)/80% N(2), 100% N(2) and vacuum (2). In an additional experiment, slices of beef semimembransosus muscles were stored for 10 days in 100% CO(2), 100% N(2) and vacuum. Cooking loss of ground beef patties was higher of all CO(2) treatments than non-CO(2) treatments (p<0.05). Storage of raw ground beef in CO(2) caused a concentration dependent decrease in raw meat pH of up to 0.12 units in 100% CO(2). In the beef slices, small CO(2) related fissures and pores were formed in the cooked meat. These changes in pH and microstructure probably contributed to the elevated cooking loss. The hardness of cooked ground beef was not affected by CO(2) exposure (p>0.05). Because CO(2) in concentrations of 20-100% is commonly used in industrial packaging processes for retail meat and meat trimmings, a reduction in cooking yield of 1-3% may have sensory and economic implications.     

Influence of Pre-Rigor Processing, Mechanical Tenderization, Tumbling Method and Processing Time on the Quality and Yield of Ham

Eight market weight hogs with similar genetic and management background were conventionally slaughtered with the resulting sixteen pork carcass sides randomly assigned to treatments. Four treatments at 2 levels each (2⁴ factorial design) included muscle condition [pre-rigor (hot) or post-rigor (chilled)], mechanical knife blade tenderization [no tenderization or tenderization], vacuum tumbling [continuous or intermittent], and the processing delay time between vacuum tumbling and further processing [no delay time or 20-hr delay]. Results indicated that pre-rigor processed meat tissue exhibited higher pH, water-holding capacity (WHC), and cooked yield characteristics. Mechanical knife blade tenderization consistently increased protein content of the uncooked meat exudate, cooked yield, and palatability characteristics. Tumbling method and processing time had little influence on either uncooked or cooked meat characteristics.     

Addition of tea catechins and vitamin C on sensory evaluation, colour and lipid stability during chilled storage in cooked or raw beef and chicken patties

The effects of addition of tea catechins (TC) and vitamin C (VC) on sensory evaluation, colour and lipid stability in cooked or raw beef and chicken meat patties during refrigerated storage were studied. Fresh beef striploin and chicken breast muscles were minced, following removal of external fat and connective tissue. Following mincing, beef and chicken were assigned to one of the following five treatments: control (meat treated with no antioxidant); TC200, meat plus 200 mg TC/kg muscle; TC400, meat plus 400 mg TC/kg muscle; VC200, meat plus 200 mg VC/kg muscle, VC400, meat plus 400 mg VC/kg muscle. Sodium chloride (1%) was added to all samples. Patties (125 g portions), formed from the above-treated minced meat, were oven cooked, cooled, and packaged in 30% CO₂:70% N₂. Fresh raw beef and chicken patties were packaged in 80% O₂:20% CO₂. All samples were stored for up to 7 days under fluorescent lighting at 4 °C. Sensory parameters (colour, flavour, taste, tenderness and overall acceptability) were evaluated on cooked beef and chicken patties after 1, 3 and 6 days of storage. Surface colour (Hunter L, a and b values), and lipid oxidation (2-thiobarbituric acid reactive substances) were measured on days 1, 3 and 6 of storage for cooked meats and on days 2 and 7 for raw beef and chicken. Tea catechins addition (200 or 400 mg/kg) to minced meat caused (P < 0.05) discolouration in cooked beef and chicken meat patties and significantly reduced (P < 0.001) lipid oxidation in cooked or raw beef patties compared to the control. Beef, either raw or cooked, was more susceptible (P < 0.01) to oxidation compared to chicken. Raw meat stored in high oxygen conditions was more susceptible to lipid oxidation than cooked meat stored in anaerobic conditions. Tea catechins treatments (TC200 and TC400) inhibited (P < 0.05) lipid oxidation in raw beef to a greater extent than vitamin C treatments (VC200 and VC400). These results indicate that tea catechins are potent natural antioxidants and exhibit greater antioxidant efficacy compared to vitamin C.     

Double-antibody ELISA for detection of trace amounts of pig meat in raw meat mixtures

Pre-rigor cooked beef is tender if the cooking produces severe shortening. This study was conducted to compare the effects of different heating rates on shortening and tenderness. Myofibrillar and cooking shortening and related changes were measured with physiograph recordings on pre-rigor M. triceps brachii strips suspended in paraffin oil during heating. Warner-Bratzler shear values were determined on M. triceps brachii samples heated at approximately the same rates at which the muscle strips were heated. Rapid heating (2°C/2min) produced more (p < 0·01) severe myofibrillar shortening that was complete at higher (p < 0·01) muscle temperatures than slow heating (2°C/12 min). Regardless of animal age, rapid heating resulted in a cooked product that was more (p < 0·01) tender than that produced by slow heating in the pre-rigor state and slow heating resulted in a more (p < 0·01) tender product than that achieved by rapid heating in the post-rigor state. Data on muscle shortening and from differential scanning calorimetry suggest that the tenderness produced from pre-rigor rapid heating results from a heat-induced active contraction.     

Hot Pork Processing, Brine Chilling and Mechanical Portioning as a Fresh Pork Processing System

Rapid chilling was investigated as a link between hot pork processing and mechanical portioning. Loins from market weight hogs (n = 40) were removed (pre- or post-rigor) and were assigned to one of two chilling treatments (brine chilling or blast freezing). Loins were chilled until crust frozen, then tempered, pressed and cleaved. Ultimate pH, cooking yields, taste panel ratings and Warner-Bratzler shear force values (WBS) were obtained. Pre-rigor chops had significantly higher WBS values and lower (less tender) taste panel ratings than post-rigor chops. Generally, pre-rigor chops were juicier but less tender. There were no major differences between rapid chilling treatments nor in ultimate pH or cooking data. Less severe chilling techniques are needed to make this processing system feasible.     

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.     

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.     

Effects of Metmyoglobin Reducing Activity and Thermal Stability of NADH‐Dependent Reductase and Lactate Dehydrogenase on Premature Browning in Ground Beef

Premature browning is a condition wherein ground beef exhibits a well‐done appearance before reaching the USDA recommended internal cooked meat temperature of 71.1 °C; however, the mechanism is unclear. The objectives of this study were: (1) to determine the effects of packaging and temperature on metmyoglobin reducing activity (MRA) of cooked ground beef patties and (2) to assess the effects of temperature and pH on thermal stability of NADH‐dependent reductase, lactate dehydrogenase (LDH), and oxymyoglobin (OxyMb) in‐vitro. Beef patties (lean: fat = 85:15) were packaged in high‐oxygen modified atmosphere (HiOX‐MAP) or vacuum (VP) and cooked to either 65 or 71 °C. Internal meat color and MRA of both raw and cooked patties were determined. Purified NADH‐dependent reductase and LDH were used to determine the effects of pH and temperature on enzyme activity. MRA of cooked patties was temperature and packaging dependent (P < 0.05). Vacuum packaged patties cooked to 71 °C had greater (P < 0.05) MRA than HiOX‐MAP counterparts. Thermal stability of OxyMb, NADH‐dependent reductase, and LDH were different and pH‐dependent. LDH was able to generate NADH at 84 °C; whereas NADH‐dependent reductase was least stable to heat. The results suggest that patties have MRA at cooking temperatures, which can influence cooked meat color.     

Residual triose phosphate isomerase activity and color measurements to determine adequate cooking of ground beef patties

The objectives were to (i) compare the use of triose phosphate isomerase (TPI) activity and internal color scores for determination of cooking adequacy of beef patties and (ii) determine the effect of frozen storage and fat content on residual TPI activity in ground beef. Ground beef patties (24.4% fat) were cooked to five temperatures ranging from 60.0 to 82.2 degrees C. TPI activity decreased as beef patty cooking temperature was increased from 60.0 to 71.1 degrees C; however, no difference (P > 0.05) in activity (6.3 U/kg meat) was observed in patties cooked to 71.1 degrees C and above. Degree of doneness color scores, a* values and b* values, of ground beef patties decreased as internal temperature was increased from 60.0 to 71.1 degrees C; however, temperature had no effect on L* values. TPI activity in raw ground beef after five freeze-thaw cycles did not differ from the control. Three freeze-thaw cycles of raw ground beef resulted in a 57.2% decrease in TPI activity after cooking. TPI activity of cooked beef increased during 2 months of frozen storage, but TPI activity in ground beef stored for 3 months or longer did not differ from the unfrozen control. While past research has shown color to be a poor indicator of adequate thermal processing, our results suggest that undercooked ground beef patties could be distinguished from those that had been adequately cooked following U.S. Department of Agriculture guidelines using residual TPI activity as a marker.     

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.     

Effect of Low‐Dose Electron Beam Irradiation on Quality of Ground Beef Patties and Raw,Intact Carcass Muscle Pieces

The objectives of this study were to determine the effects of a low‐dose (≤1 kGy), low‐penetration electron beam on the sensory qualities of (1) raw muscle pieces of beef and (2) cooked ground beef patties. Outside flat, inside round, brisket and sirloin muscle pieces were used as models to demonstrate the effect of irradiation on raw beef odor and color, as evaluated by a trained panel. Ground beef patties were also evaluated by a trained panel for tenderness, juiciness, beef flavor, and aroma at 10%, 20%, and 30% levels of fat, containing 0% (control), 10%, 20%, 50%, and 100% irradiated meat. With whole muscle pieces, the color of controls appeared more red (P < 0.05) than irradiated muscles, however, both control and treatments showed a gradual deterioration in color over 14 d aerobic storage at 4 °C. Off‐aroma intensity of both control and treatments increased with storage time, but by day 14, the treated muscles showed significantly (P < 0.05) less off‐aroma than the controls, presumably as a result of a lower microbial load. It was found that a 1 kGy absorbed dose had minimal effects on the sensory properties of intact beef muscle pieces. Irradiation did not have a significant effect (P > 0.05) on any of the sensory attributes of the patties. Low‐dose irradiation of beef trim to formulate ground beef appears to be a viable alternative processing approach that does not affect product quality.