LPT 321: Meat Science (1+1)

CHEMISTRY OF CURING REACTION

Muscle pigments

• There are a number of muscle pigments in meat including myoglobin, haemoglobin, the cytochromes, catalases, the flavins and other coloured substances.
• Quantitatively the first two listed myoglobin and haemoglobin are abundant.
• The lesser pigments also play role in colour development and stabilization.
• Myoglobin and haemoglobin are complex proteins and undergo similar reaction in meat.
• However, their roles in living tissues are quite different.
• Haemolglobin is the red pigment found in blood and acts as the carrier for oxygen to the tissues.
• Myoglobin is the predominant pigment in muscle and serves as the storage mechanism for oxygen at the

The Chemistry of curing reaction

• Colour develops as a result of interaction of nitrite with the muscle pigments.
• The nitrate and nitrite reactions in meat curing are as shown below
• Nitrate reducing organisms

Chemical changes of myoglobin that may occur during the curing reaction are as follows

• The ultimate pigment desired in most heat processed cured meats is the conversion of muscle pigment myoglobin into nitrosyl haemochrome (pink).

Undesirable Changes

• Under some conditions the nitrosyl haemochrome pigment in meat may be oxidized to green, yellow or colourless porphyrin substances.
• Such undesirable changes of the cured meat pigment may result from bacterial action or from chemical oxidation by peroxides, hypochlorites or other agents.
• Light catalyzes these oxidative changes, as demonstrated by the tendency of cured meat surfaces to fade rapidly under strong light.

Curing Temperature

• The curing room temperature is maintained at 3˚C in most curing commercial operations.
• Bacon factories maintain their pickling cellars between 3.3 and 5.6°C, for at this temperature the growth of microorganisms is very slow, especially in the presence of salt.