Reduction of Pink Color Development in Cooked,Uncured Ground Turkey Breast by the Addition of Dairy Proteins
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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.