| Three experiments were conducted to determine the effects of citrate (CIT) or acetate (ACE) via oral administration, feeding, or pre-rigor injection of carcasses on post mortem glycolysis, pH decline, and pork quality attributes. In experiments 1 and 2, pigs were given CIT or ACE at 0.75 g/kg of body weight using a tube placed in the esophagus 45 min ante mortem, or fed in 454 g of feed 60 min ante mortem. Neither oral administration nor feeding of CIT nor ACE affected (P > 0.05) post mortem glycolysis (measured by glycolytic metabolite concentrations) or pH decline. Minor and inconsistent differences were found in some quality traits in the longissimus, but ante mortem treatment did not affect (P > 0.05) quality in the semimembranosus muscle. Although CIT and ACE did not affect phosphofructokinase (PFK) activity, I found that PFK was the rate limiting factor in post mortem glycolysis, especially evident in the first 3 h post mortem. In experiment 3, intact carcass sides were injected in the longissimus 50 min post mortem with 4% CIT, 4% ACE, or injected 24 h post mortem with 4.4% phosphate and 2.2 % salt (PHOS), or not injected (CON). Citrate-injection increased ( P < 0.05) pH values, but neither CIT nor ACE affected ( P > 0.05) post mortem glycolysis. Longissimus chops from pre-rigor injected carcasses were softer and wetter (P < 0.05) than those from CON- and PHOS-injection, and more tender ( P < 0.05) than CON, whereas those from PHOS-injected carcasses were the most tender and juicy (P < 0.05). Chops from CIT-injected carcasses were similar (P > 0.05) to those from CON in pork flavor and off-flavor intensity, and both were superior ( P < 0.05) to flavor attributes of chops from ACE and PHOS carcasses. Citrate and ACE improved color compared to PHOS (P < 0.05) over 7 d of display, but not compared to CON (P > 0.05). Although CIT and ACE were not effective at inhibiting post mortem glycolysis, CIT injection improved tenderness, without altering flavor and color, whereas ACE-injection likely was too detrimental to pork flavor to be considered in injection-enhancement solutions. |
