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The influence of the rate of pH decline on the rate of ageing for pork. II. Interaction with chilling temperature

Rees, M.P., Trout, G.R., Warner, R.D.
Meat science 2003 v.65 no.2 pp. 805-818
boars, slaughter, electrical treatment, carbon dioxide, meat aging, cold storage, cooling, storage temperature, protein degradation, rigor mortis, pH, sarcoplasmic reticulum, solubility, sarcomeres, tenderizing, meat quality, shear strength, principal component analysis
The influence of the rate of pH decline post slaughter on the rate of ageing of pork m. longissimus thoracis et lomborum was investigated. The rate of pH decline on 24 finisher pigs was manipulated by altering the method of stunning (carbon dioxide or electrical head to heart) and by the use of electrical stimulation (none or low voltage electrical stimulation (LVES) at 4 min post slaughter for either 15 s or 60 s). The rate of temperature decline was altered by chilling at 2 or 14 degrees C until rigor. The pH and temperature decline rates generated were designed to induce cold shortening at one extreme and protein denaturation at the other. The research results showed that the rate of pH decline was increased by electrical stimulation which in turn reduced cold shortening and improved tenderness. Chilling at 14 degrees C reduced the time to reach rigor by 1.3 h and resulted in a faster aging rate as indicated by a larger percentage change in WBSF from rigor to 4 days postmortem relative to carcases chilled at 2 degrees C. The greater tenderising effect appeared to be due to a combination of prevention of cold shortening and increased proteolysis. However, chilling slowly at 14 degrees C or the use of LVES for 60 s or any combination of these treatments did not induce protein denaturation.