MEAT PRESERVATION

• Spoilage can be defined as any change that renders a food product

  unacceptable for human consumption (Hayes, 1985).
• the pre-slaughter period (that period after the animal is last

  removed from feed)
• PRE-SLAUGHTER PERIOD:

  • muscle glycogen 1%
  • muscle glycogen 0.4%
  • 0.6% glycogen depleting event
  • 1.8% glycogen
  • muscle glycogen level of 1.2%
• A.Transportation

  B. Marketing

  C. Lair aging

  D. Effects of stunning and slaughter on meat quality
• Contamination of meat

  The healthy inner flesh of the meat contains few or no micro-organisms although

  they have been found in lymph node and bone marrow.
• microbial spoilage of meat can be classified on the basis of whether

  they occur under aerobic or anaerobic condition and whether they are caused by

  bacteria, yeast, or mold.
• surface spoilage- It is caused by Pseudomonas,

  Acenatobacter,Streptococcus,Leuconostoc,

  Bacillus and Micrococcus.
• change color of meat-Red color of meat may be changed into green

  brown or grey due to production of oxidising

  agent, H2S, etc. by microorganisms.
• change in fat-Fat of meat may become rancid due to lipase

  producing microorganisms such

  as Pseudomonas and Achromobacter.
• Surface color due to pigmented bacteria-Serratia marcescens give red spots.
• Phosphorescence-It is caused by luminous bacteria

  e.g. Photobacterium growing on surface of

  meat.
• Off odors and off taste-Undesirable odor and taste called taint are

  caused by many bacteria due to production

  of volatile acids such as formic acid, acetic

  acid, butyric acid etc.
• Souring:

  -It is caused by formic acid, acetic acid, butyric acid, propionic acid, higher

  fatty acids and other organic acids. E.g. lactic acid produced by bacteria.

  -Souring may also be caused by foods own enzyme.
• Putrefaction:

  -It refers to the anaerobic decomposition of protein with production of

  offensive smelling compounds such as H2S, mercapatans, indole, skatole

  etc.
• Taint:

  -It refers to any undesirable odor or taste.
• a.Asepsis prevents external microorganisms from entering into the meat.

  b. Water spraying before slaughter is recommended to remove dirt and

  microorganisms from hair and hide and foot bath may be used to remove dirts

  from hoofs.

  c. Other method of asepsis includes sanitization of knife, used for killing and

  personal hygiene of food handler.

  d. Films may be used to keep out bacteria and other microorganisms.
• Canning is a specialized technique of preservation for meat.

  Self-stable canned meat:

  -The processing temperature is 98oC and the size of container is usually less

  than 1lb.

  -They are made sterile or at least commercially sterilized.
• Non-self stable canned meat:

  -The processing temperature is about 85oC and the size of container is up to

  22 lb.

  -They kill only part of spoilage organisms and the meat must be kept frozen

  to prevent spoilage.
• a.Chilling temperature vary from -1.4oC to 2.2oC with the lower temperature

  preferred.

  b. Meat are chilled rapidly because there is opportunity for growth of

  mesophiles if cooled suddenly.

  c. The time limit for chilling storage depends on meat. For.eg. 30 days for

  beef, 1-2 weeks for mutton.
• a.Freezing is increasingly effective as the temperature drops from -12.2oC

  towards -28.9oC.

  b. Meats are frozen quickly in package.

  c. Freezing process kills about half of the bacteria and their number

  decrease slowly during storage.
• Chemical preservatives are added in meat as a component of wood smoke and

  curing solution.
• Commonly smoke is obtained by burning hard wood, and

  temperature of smoking generally vary from 48oC- 72oC. Smoking period lasts from a

  few hours to several days.
• a.It is a common preservation method for meat.

  b. Both solid cuts and ground meat are subjected to curing.

  c. Curing agents permitted in meat are NaCl, sugar, sodium nitrate and vinegar,

  but only the first three are commonly used.

  d. There are few methods of introducing curing agents in meat:

  e. The dry cure in which the dry ingredients are rubbed into the meat

  f. The curing temperature (especially with pickle cure) usually is about 2.2oC –

  3.8oC and the time of curing vary with the meat and the method used.
• NaCl: It lowers Aw and gives flavor.

  Sugar: It lowers Aw and gives flavor.

  Vinegar: It is preservative.
• Sodium nitrite: It is a coloring agent.
• Meat fermentation is a method for improving the keeping

  qualities of perishable meats.
• Some of the fermented meat products are:

  1. Sausage / Hotdog

  2. Ham

  3. Chorizo

  4. Tocino