LPT 321: Meat Science (1+1)

THAWING OF FROZEN MEATS

• Thawing or defrosting of frozen meat is usually done before cooking.
• This is done in order to bring the meat to the room temperature.
• Defrosting may be achieved in many ways, viz.,
  • Slow defrosting in a refrigerator or in cold air
  • At room temperature in a rack or warm air
  • In circulating cold water and
  • Quick de-frosting in warm water or cooked without prior thawing.
• Defrosted meat is cooked in the same way as fresh meat.
• Meat, when thawed, sometimes produces a water fluid called “Weep or Drip”.
• This fluid mainly consists of water, salts.
• Due to the presence of large ice crystals in muscle, protein is also to some extent unable to reabsorb the entire water when the meat is thawed.
• In the present context of preservation of meat, the drip fluid offers a good medium for growth and multiplication of bacteria, which is present in the frozen meat.
• Therefore, thawed meat is liable to spoil quickly than fresh meat. As the shelf life of the thawed meat is low, re-freezing of such thawed meat will materially yield meat of poor stability.
• Palatability differences among thawing methods are negligible.
• The method of thawing affects the amount of moisture or drip loss from the meat.
• The extent of this loss from a given product depends also upon the temperature at which the meat was held during frozen storage.
• Fluctuating temperatures tend to increase the drip loss on thawing.
• As a practical matter, frozen meats that have more drip loss during thawing loose less moisture during cooking; the over all drip loss from the frozen to the cooked state is almost the same for all the methods of thawing.
• The time required for thawing frozen meats depends upon the temperature of the meat and its thermal capacity, the thawing medium (air or water) and its temperature and circulation, the size of the unit being thawed, etc.
• In situations where the thawing will take a long time, care should be taken to avoid surface temperature that will permit rapid microbial growth.
• Although the microorganisms do not grow faster on thawed meat than on fresh meat, the product is very perishable as soon as the surface temperature goes 0°C (32°F).
• Therefore, frozen meat should not be thawed too long before cooking.
• In refrozen thawed meat, there will be increased damage to the tissues, which will cause an increased drip loss, thus a loss of more water-soluble nutrients, and there will be some decrease in palatability.
• Meat, which has a high pH prior to freezing, has a low drip when thawed.

Sl. No.	Factors	Chilling	Freezing
1.	Temperature	-1.1ºC (30ºF)	Much below -1.4ºC (29.4ºF)
2.	Durability	Less (35 days)	Beef-1 year Mutton-9 months Pork-6 months
3.	Bloom	Excellent	Lost
4.	Colour	Present	Absent
5.	Kind	Only high grade meat alone can be used	Any kind of meat can be used.