A sporadic pink color development in cooked, uncured turkey products remains a problem within the poultry industry because consumers associate this defect with inadequate cooking. Previous research demonstrated that nonfat dry milk (NFDM) has the ability to reduce pink color. The objective of this research was to determine if other dairy proteins also possess this capability. In particular, sodium caseinate (SC) and whey protein concentrate (WPC) were evaluated and compared to nonfat dry milk and to no dairy protein containing processed turkey. Pink color development was induced in the poultry products to simulate this defect in products by the addition of nicotinamide to produce nicotinamide hemochrome or sodium nitrite or sodium nitrate to produce nitrosylhemochrome. Prior to protein testing, measurement of these two pigment using reflectance spectrophotometric methods was evaluated. The reflectance ratio of %R at 537 nm divided by %R at 553 nm was able to predict (R²=0.99) concentrations of nicotinamide up to 2%, the highest level tested. The ratio of %R at 650 nm divided by %R at 570 nm was able to predict nitrite (R²=0.97) below 20 ppm. To narrow the possible dairy protein choices, three WPC and two SC dairy proteins, along with nonfat dry milk were evaluated for their ability to inhibit nicotinamide and nitrite induced pink color. Results of this prescreening indicated that variations among the different types of proteins existed in both their abilities to reduce the pink color when pink color generating ligands were intentionally added, and when no ligands were added. Some of the dairy proteins actually increased the redness of the control turkey formulation. The WPC (Alacen 882, New Zealand Milk Products, North America, Inc, Santa Rosa, CA) and SC (Alanate 180 New Zealand Milk Products, North America, Inc., Santa Rosa, CA) protein products chosen in the prescreening were evaluated with nonfat dry milk at various levels. A simplex lattice response surface design enabled prediction of these proteins' effects on red color at combinations of up to and including 3.0% added dairy protein. Sodium nitrate did not appear to increase redness of control samples and therefore was not discussed in detail. The WPC and NFDM proteins tested were able to reduce CIE a* values at both 1.5 and 3% and in combination with each other at 1.5% of each protein (P<0.05) regardless of ligand treatment. Of these treatments, SC had the least effect on CIE a*. With the exception of SC, the dairy proteins increased product yield (P<0.05) in all treatment combinations. Using the response surface prediction ability, other combinations of dairy proteins, not specifically tested in this research, were shown to optimize pink color reduction. / Master of Science

Sporadic problems with pink color defect, or pinking, has occurred in cooked meat products for decades. Pink color can be due to the presence of undenatured myoglobin, denatured globin hemochromes, or nitrosylhemochrome. This research documented the level of added nitrite that produced nitrosylhemochrome in processed meat rolls from fabricated beef round, pork shoulder, turkey breast, and chicken breast. For each meat type, preliminary studies were conducted to narrow the range at which added nitrite caused pinking. Subsequently, the nitrite levels were increased incrementally by 1-ppm, and pink color was measured by trained panelists and by a Hunter color meter. Nitrosylhemochrome content was determined by acetone extraction. Panel and instrumental measurements identified pink color in beef samples formulated with 14-ppm nitrite; nitrosohemochrome extracts detected pigment at 12- ppm. Nitrite levels that caused pinking in pork shoulder were much lower than in beef. Panelists identified pink color at 4-ppm nitrite, and Hunter color meter values showed increased redness at 6-ppm. Pigment extraction detected nitrosylhemochrome at 4- ppm added nitrite. The trained panel and Hunter color meter detected pink color in turkey breast at 2-ppm added nitrite; nitrosohemochrome extraction detected pink pigment at 3-ppm added nitrite. In chicken breast, pink color was detected visually and instrumentally at 1-ppm added nitrite. Pigment extraction detected nitrosylhemochrome at 2-ppm added nitrite. Lower levels of nitrite (1-3-ppm) caused pinking in light-colored meats (turkey and chicken breast, meats with total pigment between 19-ppm and 27-ppm). Higher levels of nitrite (5-14-ppm) caused pink color defect in dark pigmented meat (beef round and pork shoulder, meats with total pigment levels between 56-ppm and 147-ppm). Regression analysis was used to relate total pigment and the minimum level of nitrite causing pinking. The minimum nitrite level causing pinking was the lowest level of nitrite at which the trained panel, acetone extraction, and instrumental results detected pink color or nitrosyl pigment. The formula obtained from the model was as follows: Y = 0.092X + 0.53, where "Y" is the minimum level of added nitrite to cause pinking and "X" is the total pigment of the meat. This formula can be used to estimate the level of nitrite that can be expected to cause pinking in a wide range of pigmented meats.

The pink color defect in cooked, uncured turkey is a sporadic problem which can result in consumer dissatisfaction. Nicotinamide hemochrome may be one of the major pigments responsible for this defect. Reflectance (400-700 nm) methodology was developed to reliably and easily quantify (%R 537 nm/%R 553 nm; r = 0.993) the presence of nicotinamide hemochrome. Fourteen ligands were tested in a ground turkey system to determine their ability to reduce pinking in control samples and in the presence of pinking agents (1.0% nicotinamide or 150 ppm sodium nitrite). Trans 1,2-diaminocyclohexane-N,N,N’,N’ tetraacetic acid monohydrate (CDTA); diethylenetriamine pentaacetic acid (DTPA), ethylenedinitrilo-tetraacetic acid disodium salt (EDTA), and calcium reduced non-fat dry milk (NFDM) were the most effective at reducing pinking with and without pinking agents. These four ligands were evaluated in intact turkey breasts with and without added pinking agents (1.0% nicotinamide or 20 ppm, 100 ppm sodium nitrite). Ligands were evaluated at various levels (50, 100, 200 ppm; except NFDM 1.0% or 2.0%), over three storage times (1, 14, 21 days), and after two minutes of exposure to light and air. When ligands were evaluated without pinking agents, samples were generally lighter and less pink than controls. In the presence of added pinking agents, the ligands were more successful at reducing nicotinamide pink than nitrite pink. As storage time increased, samples became more pink and the addition of ligands was only successful in delaying this affect. One of the most effective ligands, DTPA, reduced the sample CIE a* value 31.7% when tested alone and 30.8% in the presence of nicotinamide. NICHEM was also effectively reduced by DTPA. In general, 50 ppm of added ligand was sufficient to produce a significant reduction in pinking. / Master of Science