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EFFECTS OF PRERIGOR CONDITIONING TREATMENTS ON LAMB MUSCLE SHORTENING, pH AND ATP
- BOWLING, R. A., SMITH, G. C., DUTSON, T. R., CARPENTER, Z. L.
- Journal of food science 1978 v.43 no.2 pp. 502-514
- adenosine triphosphate, air, electrical treatment, energy expenditure, lamb carcasses, lambs, longissimus muscle, pH, relative humidity, sarcomeres, shrinkage, temperature
- Effects of prerigor conditioning treatments on processing time, quality characteristics and muscle properties were determined using three muscles from each of 84 lamb carcasses. Carcasses (n = 72) were subjected, beginning 1 hr post‐exsanguination, to one of six conditioning treatments and compared to normally chilled lambs (n = 12). Treatments differed in conditioning period, conditioning chamber environment (temperature, relative humidity, air velocity) and in use of electrical stimulation. All carcasses were maintained at 0°C after the 2‐8 hr conditioning period until fabrication at 72 hr postmortem. Panel ratings (SPR), shear force (SF), water‐holding capacity (WHC) and sarcomere length (SL) were determined for longissimus dorsi (LD), biceps femoris (BF) and semimembranosus (SM) muscles. Lambs in treatments +49 and +32 had the slowest rate of temperature decline, high rates of pH and ATP decline, low WHC, the most pronounced sarcomere shortening and the toughest LD and BF. Carcasses in the +16 treatment reached temperatures critical to cold shortening (9‐11°C) 8‐9 hr later than carcasses in the ‐16 treatment, had longer sarcomeres, had more tender BF (SF) and SM (SPR and SF) muscles but had much lower WHC. Among carcasses conditioned at ‐32°C, those which were electrically stimulated (ES) had lower carcass temperatures at 3 and 4 hr postmortem, had faster rates of pH (LD and BF) and ATP (LD) decline and lower WHC but did not differ in tenderness from those which were not ES. Production of tender lamb, with minimal energy expenditure and no increase in cooler shrinkage, was best accomplished by chilling lambs for 8 hr at +16°C (65% relative humidity and 9m/min air velocity).