In this article we will discuss about the spoilage of different kind of meat.
1. Fresh Meat:
Pork is the only meat which spoils more readily than other meats because of its high content of Vitamin B. Lactic acid bacteria chiefly Lactobacillus, Leuconostoc, Streptococcus, and Pediococcus are present in either meats and can grow even at refrigerated temperature. Lactic acid bacteria cause slime production especially in the presence of sucrose give green colouration and souring.
2. Fresh Beef:
Fresh beef undergoes the changes in the haemoglobin and myoglobin, the red pigment in the blood muscles, respectively, so as to cause loss of bloom and the production of reddish brown methaemoglobin and met-myoglobin (Fig. 21.3) and the green grey brown oxidation pigments by action of oxygen and microorganisms action. Pseudomonas and Micrococcus grow in beef, held at 10°C or lower.
It usually putrefies at room temperature. Among the genera reported are Bacillus, Clostridium, Escherichia, Enterobacter, Proteus, Pseudomonas, Alcaligenes, Lactobacillus, Leuconostoc, Streptococcus, Micrococcus and Sarcina. Penicillium and Mucor grow on hamburger.
4. Fresh Pork Sausage:
It is made up of ground fresh pork to which salt and spices have been added. It must be kept in refrigerators. Alternaria has been found to cause small dark spots refrigerated links. Souring, the most common type of spoilage at 0°C to 11°C has been attributed to growth and acid production by Lactobacillus and Leuconostoc.
5. Cured Meat:
Curing salts make meats more favourable to growth of Gram-positive bacteria, yeasts and molds than to Gram-negative bacteria which usually spoil meats. The load of microorganisms on the piece of meat to be cured may influence the deterioration and will affect the curing operation.
6. Dried Beef or Beef Hams:
Beef hams are made spongy by species of Bacillus, sour by a variety of bacteria, red by Halobacterium salinarium or due to Bacillus species. Gas in jars of chipped dried beef has been attributed to a denitrifying aerobic organism that resembles Pseudomonas fluorescens. The gases are oxides of nitrogen. Bacillus species produce CO2.
In the presence of enough moisture, micrococci and yeasts can form a slimy layer. With less moisture, molds may produce fuzziness and discolouration. Various bacteria are responsible for the greening due to the production of peroxides. Surface slimyness often accompanies the greening. Bacon and Ham are the other meats which become putrefied by various bacteria.