Characterization of the Residual Pink Color in Cooked Turkey Breast and Pork Loin

The residual redness was characterized in well cooked meat from turkey breast and pork loin. A simple method of scanning thin slices by transmission spectrophotometry was used to evaluate the meat pigments in situ. Absorption bands at 414, 520, and 550 nm of the spectra obtained from cooked meat led to the conclusion that residual pink color was caused by cytochrome c. The method was further modified to study the effect of air contact on meat color after cooking. Other pigments were spontaneously oxidized as soon as meat surface was exposed to air. The concentrations of hemoproteins in turkey and pork were determined and found to be related to cooked meat color.     

Spectra of Pigments Responsible for Pink Color in Pork Roasts Cooked to 65 or 82°C

Undenatured oxymyoglobin and deoxymyoglobin were the pigments responsible for pink color in pork roasts cooked to 65°C. Roasts cooked to 82°C had gray internal color after cooking, but panelists noted development of pink internal color after refrigerated storage. Reflectance spectra of pink slices from roasts cooked to 82°C, then stored for 12 days at 2°C, were characteristic of denatured globin hemo-chromes or related nonnitrosyl hemochromes.     

Whey protein concentrates effects on pink color development in a cooked ground turkey breast model system

The ability of whey protein concentrates (WPCs) to reduce pink color in cooked ground turkey was investigated. Ground turkey was formulated with no ligand and nitrite and nicotinamide to induce pinking. Five WPCs with 34 or 80% protein were tested and turkey samples were cooked to 80 and 85 °C and stored for 1 and 7 days. Three WPCs reduced a* values in turkey without added nitrite or nicotinamide and one WPC reduced nitrite induced pinking. In nicotinamide-induced pink turkey, two WPCs reduced a* values and two WPCs increased pink color. Nitrosylhemochrome was reduced by two WPCs and nicotinamide hemochrome was reduced by one WPC and increased by two WPCs. Increased cooking temperatures enhanced inhibitory effects or reduced reddening effects of two WPCs. Storage time and protein content had minimal effects on pink color. Whey protein concentrates have the potential to reduce the pink defect in cooked uncured turkey, although the mechanism is unclear.     

Mechanisms of Pink Color Formation in Irradiated Precooked Turkey Breast Meat

ABSTRACT: Precooked turkey breast meat was aerobically packaged or vacuum-packaged and irradiated at 0, 2.5, or 5.0 kGy. CIE color, reflectance, oxidation-reduction potential (ORP), gas production, and lipid oxidation were determined at 0, 7, and 14 d. Irradiation increased redness of vacuum-packaged meat, and the redness was distinct and stable under vacuum. Irradiation decreased ORP and produced carbon monoxide (CO). This indicated that the pink color was caused by the heme pigment-CO complex formation. The reflectance of meat and the absorption spectra of myoglobin solution supported the assumption that denatured CO-myoglobin is the pigment in irradiated precooked turkey breast.     

Investigation of mechanisms by which sodium citrate reduces the pink color defect in cooked ground turkey

The principal mechanism by which sodium citrate reduces the pink color defect in cooked ground turkey was investigated. Sodium citrate (SC; 0, 0.125, 0.25, 0.5, 1.0, 2.0 M), sodium nitrite (0.01, 0.1 M), and nicotinamide (0.5, 0.75 M) were combined in solutions of bovine hemin to determine SCs ability to bind heme iron and competitively inhibit pink-color-generating ligands from binding. Additionally, the effects of sodium erythorbate (0, 275, 550 ppm), ferrous iron chloride (0, 0.3, 3.0, 30 ppm), and ferric iron chloride (0, 0.3, 3.0, 30 ppm) on SCs ability to reduce pink cooked color was examined. Absorbance curves of hemin + nitrite and hemin + nicotinamide were relatively unaffected by SC, therefore whether or not SC bound heme iron, that did not appear to be a mechanism for inhibiting the pink color defect. Both ferrous and ferric iron chloride had minimal effects on color values, possibly due to sodium tripolyphosphate chelation ability in the meat system and thus their presence did not enhance SCs ability to reduce the pink color defect. However, sodium erythorbate, a reducing agent, inhibited SCs ability to decrease the pink color defect in samples induced pink with sodium nitrite and nicotinamide. Therefore, it appears SC requires the presence of oxygen and may participate in oxidative processes to reduce the pink color defect.     

Calcium chloride and tricalcium phosphate effects on the pink color defect in cooked ground and intact turkey breast

Calcium chloride (250, 500 ppm) was examined for its ability to reduce the pink color defect induced by sodium nitrite (10 ppm) and nicotinamide (1.0%) in cooked ground turkey in the presence and absence of sodium tripolyphosphate (0.25, 0.5%) and sodium citrate (0.5, 1.0%). The ability of tricalcium phosphate (0.1–0.5%) to reduce pink cooked color also was evaluated in ground turkey and both calcium chloride and tricalcium phosphate were tested for their effects on pink cooked color in whole breast muscle. The combination of calcium chloride and sodium tripolyphosphate, not calcium chloride alone, was necessary for a reduction in pink cooked color induced by nicotinamide. Subsequently, in the presence of phosphate, both calcium chloride and sodium citrate reduced pink cooked color and were most effective in combination. Tricalcium phosphate also was capable of reducing pink cooked color in ground turkey, however substituting tricalcium phosphate for sodium tripolyphosphate resulted in lower pH and cooking yields. Neither calcium chloride nor tricalcium phosphate was capable of reducing pink cooked color in whole turkey breast. Currently, a combination of sodium tripolyphosphate, calcium chloride, and sodium citrate represents the most suitable means for reducing or preventing the pink color defect in uncured ground turkey.     

Pink Color Defect in Poultry White Meat as Affected by Endogenous Conditions

ABSTRACT The pinking defect in cooked, uncured meat has been a problem in the poultry industry for nearly 40 years. Through the years, analyses of data revealed various processing factors that seem to influence the specific biochemical conditions (pH, redox potential, denaturation, reacting ligands) of the meat that are related to the chemical state of the pigments in cooked meat, their structure, and reactivity. This review addresses endogenous conditions that affect the pigments' reactivity, and research studies conducted on in situ conditions resulting in pinking in cooked meat. Future studies could be devised for understanding mechanisms leading to developing processes for reduction/elimination of the pink defect in cooked white poultry meat.     

Citric Acid and Sodium Citrate Effects on Reducing Pink Color Defect of Cooked Intact Turkey Breasts and Ground Turkey Rolls

ABSTRACT The ability of citric acid (0.1%, 0.2%, 0.3%) and sodium citrate (1.0%) to reduce the pink color defect induced with sodium nitrite (1 ppm, 5 ppm, 10 ppm) and nicotinamide (0.5%, 1.0%) in cooked, intact turkey breasts and ground turkey rolls was examined. Citric acid at 0.2% and 0.3% and sodium citrate consistently reduced natural or induced pink color in ground turkey rolls but had no effect on pink color of intact turkey breasts. Citric acid reduced pH and cooking yields, whereas sodium citrate did not. Therefore, sodium citrate may represent a viable option for use by poultry processors in reducing the occurrence of undesirable pink color in cooked, uncured, ground turkey.     

Effect of Antioxidants on Consumer Acceptance of Irradiated Turkey Meat

Antioxidants had no effect on the production of sulfur compounds, color change, and off‐odor intensity of irradiated turkey breast meat, but addition of sesamol + tocopherol or gallate + tocopherol was effective in reducing thiobarbituric acid‐reactive substance values and aldehydes, especially under aerobic conditions. Consumers preferred the color of irradiated raw and cooked meat to nonirradiated meat because the pink color of irradiated meat looked fresher. The packaging method was more important than the antioxidant treatment in reducing irradiation off‐odor because S‐compounds produced by irradiation easily volatilized under aerobic packaging conditions. Therefore, the combined use of aerobic packaging and antioxidants is recommended to improve consumer acceptance of irradiated poultry meat.     

Identifying constituents of whey protein concentrates that reduce the pink color defect in cooked ground turkey

Whey protein concentrate constituents were tested for their ability to reduce naturally occurring pink color defect and pink cooked color induced by sodium nitrite (10 ppm) and nicotinamide (1.0%) in ground turkey. β-lactoglobulin (1.8%), -lactalbumin (0.8%), bovine serum albumin (0.15–0.3%), lactose (1.0–3.0%), potassium chloride (500–1500 ppm), and ferrous iron chloride (0.3–30 ppm) had no effects on cooked pink color. Lactoferrin (30–5000 ppm) increased or decreased pink color depending on its concentration in samples without added sodium nitrite or nicotinamide. Annatto (0.1–1.0 ppm) reduced pink color whereas the higher concentration of magnesium chloride (22–88 ppm) and ferric iron chloride (0.3–30 ppm) increased pink color in samples with added nicotinamide. Calcium chloride (160–480 ppm) was the only tested constituent that consistently reduced pink cooked color in samples with and without added nitrite and nicotinamide. Due to the variability of whey protein concentrates and the number of constituents that do not reduce pink cooked color, the addition of calcium alone or dried milk minerals containing calcium, phosphate, and citrate, represents a better means to regularly prevent the pink color defect in cooked ground turkey.     

Mass spectrometric characterization and thermostability of turkey myoglobin

Pink color defect (PCD) is a major quality problem in the turkey industry leading to pink appearance of pre-cooked, uncured turkey. The present study determined the molecular mass of turkey myoglobin (Mb) using mass spectrometry and characterized the thermostability of turkey Mb, in comparison with beef Mb, to elucidate the molecular basis of PCD. Purified turkey and beef myoglobins were analyzed using Matrix Assisted Laser Desorption Ionization Time of Flight Mass Spectrometry. The thermostability of turkey and beef oxymyoglobins was examined at pH and Mb concentrations (pH 6.2 and 0.04 mmol/L for turkey; pH 5.6 and 0.15 mmol/L for beef) reflecting inherent conditions in these meats. Turkey and beef oxymyoglobins were incubated at 71, 75, and 80 °C and percentage myoglobin denaturation (PMD) was determined. Molecular mass of turkey Mb (17,295 Da) was 346 Da greater than beef Mb (16,949 Da) and was approximately 300-350 Da greater than those of other red meat myoglobins, suggesting its unique primary structure. PMD was lower (P < 0.05) in turkey Mb than in beef Mb during incubation at 71, 75 and 80 °C, indicating that in-situ turkey Mb is less susceptible to heat-induced denaturation than beef Mb at typical meat cooking conditions. The observed greater thermostability of turkey Mb compared to beef Mb could be, partially, due to inherent greater pH in turkey than in beef. Possible unique primary structure of turkey Mb could have contributed to its greater thermostability, which is one of the reasons for PCD.     

Pink Color Development in Turkey Meat as Affected by Nicotinamide, Cooking Temperature, Chilling Rate, and Storage Time

Consumers associate pink color in cooked turkey with undercooking. “Pinking” has been attributed to several factors, but remains a problem in the poultry industry. Effects of temperature, chilling rate, and storage time were investigated relative to pink color intensity of turkey meat cooked in the presence of 2% nicotinamide. As final cook temperature increased, sensory pinkness increased as did CIE a* values. Slower chilling rate resulted in higher CIE a* values and lower CIE b* values. Increased storage time generally increased CIE a* values and decreased b* values while CIE L* values were not affected.     

Extraction of Pigments from Mechanically Deboned Turkey Meat

Several extraction procedures were tested to lighten the color and improve textural characteristics of mechanically deboned turkey meat. An extensive extraction of heme pigments was achieved when 0.04M phosphate buffer with a pH of 8.0 was used. Lightness of MDTM increased by 51. I%, redness decreased by 64.0%, and yellowness increased by 26.0% over untreated raw MDTM when measured objectively. Sensory analyses of cooked patties made from extracted MDTM from necks and ground turkey breast indicated that breast meat products could be formulated with 5–20% washed MDTM without significantly affecting overall sensory quality.     

Citric acid and sodium citrate effects on pink color development of cooked ground turkey irradiated pre- and post-cooking

The effects of citric acid (0.15%, 0.3%) and sodium citrate (0.5%, 1.0%) on pink color development in ground turkey following irradiation (0, 2.5, 5.0kGy) were examined. Citric acid and sodium citrate had little effect on pink color when samples were irradiated prior to cooking. In contrast, when samples were cooked prior to irradiation, citric acid (0.3%) and sodium citrate (1.0%) reduced redness as indicated by eliminating a reflectance minimum at approximately 571nm, lessening greater reflectance in the red wavelength region, and preventing greater reducing conditions caused by irradiation. Citric acid significantly reduced pH and yields whereas sodium citrate reduced pH and yields to a lesser extent. Both citric acid and sodium citrate are potential ingredients that can be added during processing to prevent undesirable pink color in precooked irradiated ground turkey and therefore can result in greater acceptance of irradiated products by consumers.     

Cooked Chicken Breast Meat Conditions Related to Simulated Pink Defect

ABSTRACT: The objective of this research was to determine the effect of modified in situ conditions on the pink defect in chicken breast meat. Processing plant and replications had no significant effect on the simulation study. Simulation of the pink defect (based on subjective pink threshold) was achieved both with and without sodium nitrite. Simulated pink defect was significantly affected by lightness of raw muscles, increased pH, and decreased oxidation-reduction potential. The results of this study can lead to establishing a pink threshold for the poultry industry and developing alternate processing methods to eliminate any pink defect.     

Lipid Oxidation, Volatiles, and Color Changes in Irradiated Raw Turkey Breast During Frozen Storage

ABSTRACT: Raw turkey breasts were aerobically or vacuum-packaged, irradiated with a linear accelerator, and frozen for 0, 1.5, or 3 mo. Lipid oxidation, volatiles, color values, gas production, and oxidation-reduction potential of the samples were determined. Irradiation produced off-odor volatiles associated with lipid oxidation and sulfur-volatiles; the off-odor was much higher in aerobic packaging. Volatiles increased with irradiation dose, aerobic packaging, and storage time. Irradiation increased stable pink color with both aerobic and vacuum-packaging. Irradiation increased the production of carbon monoxide (CO) and reducing property, indicating that CO-myoglobin could be responsible for the pink color. Lipid oxidation and color changes were not related in irradiated frozen turkey.     

Ability of Various Dairy Proteins to Reduce Pink Color Development in Cooked Ground Turkey Breast

Dairy proteins were evaluated for their ability to reduce pink color in ground turkey samples. Sodium nitrite and nicotinamide were added to induce pink color formation. Nonfat dry milk (NFDM) and 1 of the whey protein concentrates (WPC) reduced CIE a* values in samples containing 10 ppm sodium nitrite. All of the dairy proteins tested reduced CIE a* values in nicotinamide-treated samples. In samples prepared without nicotinamide or nitrite, only WPC reduced CIE a* values, while the other proteins tested had no effect or increased redness. NFDM or specific WPC proteins could be used to reduce the pink color defect and increase yield.     

Use of poultry protein isolate as a food ingredient: sensory and color characteristics of low-fat Turkey bologna

The potential of using poultry protein isolate (PPI) as a food ingredient to substitute either soy protein isolate (SPI) or meat protein in turkey bologna was investigated. PPI was prepared from mechanically separated turkey meat using pH-shift technology and the prepared PPI was added to turkey bologna at 2 different concentrations (1.5% and 2% dry weight basis). Product characteristics were compared with those prepared with the addition of 2% SPI, 11% meat protein (control-1), or 13% meat protein (control-2). All the 5 treatments were subjected to sensory analysis to evaluate aroma, appearance, color, flavor, saltiness, juiciness, firmness, and overall acceptability of the turkey bologna samples using 9-point hedonic scales. A turkey bologna control sample with 11% meat protein appeared to be softer compared to other treatments as revealed by texture profile analysis while purge loss during storage in a retail display case was significantly (P < 0.05) higher compared to other treatments. Lightness (L*) value of the products decreased during 4 wk of retail storage. A turkey bologna control sample with 13% meat protein appeared to be darker and more reddish compared to other treatments. Replacing meat protein with protein isolates caused increase in yellowish color of turkey bologna. Sensory analysis concluded that 1.5% PPI and 2% PPI could be used as substitute of SPI or lean meat and the treatments could be improved by increasing saltiness and decreasing firmness. PRACTICAL APPLICATION: The study revealed that with slight modifications in saltiness, turkey bologna can be prepared with the addition of poultry protein isolates as an acceptable substitute for soy protein isolate or meat protein. This will help to avoid usage of nonmeat ingredients (as SPI substitute) and to reduce the cost of production (as meat protein substitute) of low-fat turkey bologna.     

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.     

QUALITY AND STORAGE STABILITY OF FRANKFURTERS CONTAINING 15% MECHANICALLY DEBONDED TURKEY MEAT

SUMMARY –Fresh and frozen stored mechanically deboned turkey meat was incorporated into frankfurters at the 15% level and compard to red meat frankfurters. Mechanically deboned turkey meat exhibited higher emulsifying capacity than beef but lower than pork on a protein basis. This trend for emulsifying capacity was reversed when reported on a total meat basis. Emulsion stability was not essentially affected by the addition of 15% mechanically deboned turkey meat in red meat frankfurters. Differences flavor tests, preference flavor tests, and TBA values indicated that frankfurters containing 15% mechanically deboned turkey meat were comparable to all red meat frankfurters in flavor stability if fresh deboned poultry meat is used. The use of mechanically deboned poultry meat, which had undergone 90 days of frozen storage, resulted in a significantly inferior product as indicated by flavor evaluation and TBA values. Color evaluation showed slight color fading of all frankfurter treatments during storage. Microbial loads in the three frankfurther treatments showed some increased in total counts during refrigerated storage.