The autolysis of meat and why you need exposure.
What is it:
Autolysis-the process of changing the chemical composition, structure and properties of meat after slaughter, passing under the influence of their own enzymes.
After stopping the vital processes, oxygen supply stops, synthesis slows down and final metabolic products accumulate in the tissues. The presence of catalytically active enzymes leads to the disintegration of tissue components, changes in mechanical strength, taste, color and aroma.
Stages Of Autolysis
fresh meat → rigor Mortis → the post-mortem rigor Mortis and maturation → deep autolysis
What happens at each stage:
Fresh meat (poultry up to 30 min., beef 2-4 hours). Immediately after slaughter, muscle tissue relaxes, meat has a small mechanical strength, weak taste and smell. PH – 7.2. Due to the lack of oxygen in the body, anaerobic decomposition of glycogen (the main reserve carbohydrate of animals) occurs, with the formation of lactic acid and glucose. Diminishing reserves of ATP is not enough to recover the diminished relaxation of the fibers. Therefore, the muscles remain flexible as long as they receive ATP (synthesized by glucose). After the supply of ATP is exhausted, the muscles tense up and do not weaken — the process of rigor Mortis.
The speed of glycolysis can be regulated — the introduction of sodium chloride suppresses the process, electrical stimulation - accelerates. Stress the animals before slaughter causes the in vivo disintegration of glycogen.
Rigor Mortis (3 hours after slaughter)
Rigor mortis leads to a sharp increase in mechanical strength (meat remains tough even after cooking), color and odor deterioration. For beef Mortis reaches its maximum after 24 to 28 hours at 0 C. after 24 hours, the reserves of ATP runs out, what stops glycolysis. The accumulation of lactic acid shifts the pH to the acidic side up to 5.5. The bicarbonate system of muscle tissue is destroyed, the collagen of connective tissue swells, the process of lipid oxidation is activated.
After full rigor Mortis the muscles are relaxed, there comes the resolution of rigor Mortis. Mechanical strength decreases, water-binding capacity increases. However, organoleptic characteristics reach an optimal level only with the further development of autolytic processes.
The most important properties of meat achieve their optimal performance not at the same time. Stiffness is most markedly reduced by 5-7 days and then slowly continues to decline. Culinary characteristics of meat (taste, smell and digestibility) reach optimum in 10 - 14 days.