Meat Science and Nutrition
Aging of Meat Carcasses
The overall time for dry aging carcass meats is dictated by the quality and performance of the refrigeration used, the overall condition and handling of the carcass at the time of harvesting, and the hygiene standards of the harvesting plant. For example, while stored at 1°C (33°F), the following species would take varying amounts of time to reach approximately 80% of maximum tenderness:
- Beef: 9 to 14 days
- Lamb: 7 to 14 days
- Pork: 4 to 10 days
Note: Wet-aged (vacuum-packaged) beef can be aged much longer (up to 30 days). Lamb and pork can also be stored longer as a wet-aged product but not quite as long as beef.
Toughness and Age
Both the age of the animal at the time of processing and the post mortem aging affect its toughness. Toughness can be divided into two types:
- Background toughness: More cross links are found in older animals, making the meat tougher. Cross links refer to elastin and collagen rings that hold muscle fibres in place. As animals age, more elastin rings are formed. Also, the more exercised muscles of the animal, such as shanks and shoulders, have more elastin rings regardless of age.
- Actomyosin or myofibril toughness: This toughness is caused by the overlap of thick and thin muscle filaments.
Post mortem aging at the resolution stage of rigor mortis helps eliminate actomyosin toughness, but not background toughness. Table 2 shows the ideal age of animals for processing different types of meat. Animals processed older than the age indicated will have increased levels of background toughness.
| Meat type | Approximate age of animal at processing |
|---|---|
| Beef | 1.5 to 2.5 years |
| Veal | Less than 1 year |
| Baby veal | 3 to 6 months |
| Pork | 6 months |
| Lamb | 3 to 11 months |
| Poultry | 3 to 6 weeks |
Use of Electrical Stimulation to Speed Up the Aging Process
Electrical stimulation (ES) is a method of accelerating the normal decline of pH onset post mortem. In Canada, it is used mainly on lamb carcasses to enhance the tenderization process and protect from cold shortening. Cold shortening can occur with smaller carcasses and refers to cooling too rapidly, preventing the rigor resolution stage to be reached. ES is used to kick-start the rigor maximum stage to reach the rigor resolution stage, which improves meat tenderness and maintains the bright red colour and muscle firmness.
The standard voltage for ES is 504 volts at 3 amps. If used immediately after stunning, ES can be applied at lower voltage. However, higher voltage is more effective. If ES is delayed for one hour after stunning, a massive 1,600 volts is required to kick-start the process.
Refers to the toughness in older animals or the tougher parts of younger animals, such as shanks and shoulders, that are subject to more movement and weight distribution.
The overlap of thick and thin muscle fibres which is usually overcome during the aging process at the rigor resolution phase of rigor mortis.
A form of stimulation used to accelerate the normal decline of pH on mainly lamb carcasses in Canada.
Describes the process of a smaller carcass, such as lamb, cooling too rapidly and not reaching the rigor resolution stage.
