Page 28 - FoodFocusThailand No.156 March 2019

SPECIAL FOCUS
SPECIAL FOCUS

Pink Color Defect

in Cooked Chicken

Products

Pink color defect is the presence of a pink or undercooked/unsafe
appearance in fully cooked meat which did not added either nitrite
or nitrate even though the proper end-temperatures have reach to
ensure the food safety. This problem leads to a direct economic
concern on meat industry because of consumer rejection by
thinking that the product is not fully cooked. This problem is a major
concern in meat industry and could be found in a wide variety of
meat products. Although, this problem is not a food safety issue,
it raises a quality issue as well as an economic concern to the
meat industry.

Due to the small amount of myoglobin (natural pigment in meat) that when salt is added as ingredient during the process, the percentage
in chicken, therefore chicken meat would appear as light brown color of myoglobin denatured decreased. Thus, higher temperature is required
after cooking which give higher chance to notice the pink color defect to denature all myoglobin molecules.
when compared with other types of meat. 3. High pH of meat or using alkaline ingredients When pH of
The cause of pink color defect has been attributed to various chicken meat is higher than 6, myoglobin was more persistent to be
factors: denatured. This is because the iron in heme molecules is predominantly
1. Contamination of nitrite and nitrate in the process Nitrite is in the ferrous state (Fe ) which is higher thermal stability compared to
3+
widely used as additives especially in the curing of meat. When nitrite ferric state (Fe ). Meat produced from animal could experience high
2+
binds with myoglobin, the nitric oxide myoglobin is formed which is muscle pH from various causes i.e. preslaughter factors (such as feed,
later changed to nitrosylhemochrome after heating yield the stable hauling and handling), stunning techniques. Use of non-meat ingredients
pink color. Nitrite frequently contaminated from processing equipment especially phosphate salt which frequently added to improve marination
or containers between uncured (no nitrite/nitrate is added) and cured pick up to increase juiciness and flavor of cooked products could also
products (nitrite/nitrate is added). The previous reports showed that contribute to the occurrence of pink meat defect.
the contamination of nitrite only 1 ppm could cause a noticeable redder Moreover, there were chances of other factors to promote pink color
color in fully cooked poultry product. However, the amount of minimum defect in fully cook meat products including: (1) Addition of nicotinamide
contaminated nitrite developing pink color defect in pork and beef are or vitamin B3 in feedstuffs, (2) Chilling methods (air-chilling caused
4 and 14 ppm, respectively. higher cytochrome C content than water-chilling which could promote
In case of nitrate contamination, nitrate could convert to nitrite by pink color defect), and (3) the contamination of nitric oxide gas and
specific microorganisms with a nitrate reductase enzyme. Converted carbon monoxide gas in the process from processing equipment and
nitrite is later bound with myoglobin and form nitric oxide myoglobin, water supply, freezing-equipment, and gas-fired ovens.
same as described earlier. Nitrate is a natural inorganic nitrogen in The cause of pink color defect in uncured meat products has been
soil. Nitrate is also used as fertilizer to improve plant growth and attributed to various factors. To solve this problem, the related
development, and found in animal feedstuffs. As water moves through information together with some measured parameters from meat and
soil, it is able to pick up the nitrate and contaminate in water. Nitrate water samples were required.
contamination is much higher during the summer time. As more and Steps recommended to follow in order to solve or control pink color
more nitrate and nitrite are being found in water sources, poultry plants defect in uncured fully cooked poultry products including:
need to be aware of the quality of water being used in processing 1. Identify all potential sources of nitrite and nitrates i.e. poultry,
applications. water and ingredients
2. Use of salt as ingredient The color of cooked meat relating to 2. Monitor end point temperature
myoglobin denaturation. After cooking, soluble-myoglobin would 3. Monitor pH of poultry meat, water and other ingredients used in
change to insoluble-myoglobin. The iron molecule is released from processes
myoglobin, meat become more brown color which is irreversible 4. Avoid cross contamination of cured products (use of nitrite/nitrate)
process. Salt is known as oxidizer of myoglobin which leads to the and non-cured products (no use of nitrite/nitrate)
dissociation of oxygen from the heme moiety which promote the 5. Avoid long delays in the process especially holding before cooking
oxidation of myoglobin to metmyoglobin. Several publications indicated 6. Routinely monitor combustion gases in the process

26 FOOD FOCUS THAILAND MAR 2019

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