LPT 321: Meat Science (1+1)

CHILLING OF CARCASSES

• The carcasses of meat animals normally are refrigerated immediately after slaughter, unless they are hot boned.
• Rapid cooling is necessary to prevent spoilage around the lymph nodes deep in the carcass (referred to as bone souring).

Chilling of carcass in a modular chiller

• Beef carcasses are skinned and wrapped in shroud cloth before chilling; veal may be skinned either immediately after slaughter or after chilling, or in some cases it may be shipped skin-on.
• Pork carcasses and poultry ordinarily are not skinned.

• The regulations concerning the temperatures at which meat, offals and meat products are to be held vary in different countries.

EEC regulations recommend the following standards:

• Meat must be chilled after post-mortem inspection and must be held at a temperature of not more than +7 ⁰ C for carcasses and cuts in case of red meats, +4 ⁰ C for poultry and +3 ⁰ C for offals.
• Cutting plants must have cooling equipment to keep meat at constant internal temperature of not more than +7 ⁰ C.
• The temperature of the cutting rooms should never exceed +10 ⁰ C during cutting.
• Cutting plants must be provided with a thermometer and a telethermometer.
• South African regulations recommend the following standards
• Initial chilling of warm carcasses, sides, or quarters should be carried at 7°C and the mean air speed of above 0.75m/s, while in the terminal stages of chilling temperature must be maintained between -1°C and 2°C.
• Meat packed on trays or in cartons the temperature must be below 3°C and mean air speed of above 0.75m/s.
• For storage of chilled carcasses, sides or portions the temperature must be within the range of-1°C and 5°C and mean air speed of above 0.5m/s  over the product. The  relative humidity must be maintained below  95% or, if the product is stored for more than 72 hours, below 90%.
• Since warm carcasses will raise the cooler temperature, these rooms must not be overloaded.
• The amount of refrigeration energy required depends on the weight of the carcasses to be chilled, their temperature and their heat capacity.
• The heat capacity or specific heat of the meat depends to a large extent on the ratio of fat: lean 0.51 to 0.57 in pork to 0.70 to 0.77 in veal.
• The rate of cooling depends on the size and heat capacity of the carcass, the amount of fat covering, and the temperature in the cooler.
• Heavy carcasses may require as long as 72 hours to chill; light beef carcasses, pork, lamb and veal require up to 24-36 hours.
• Effecient chilling and  further maintaining a temperature range of   - 1°C and +0. 5°C during storage, transport and display, in conjunction with strict hygiene and excellent packaging may extend shelf life to about 12  weeks, though in commercial practice beef carcasses itself may be held without deterioration for about 35 days only.