The Nitric Oxide Synthase System Producing Nitric Oxide in Pre-rigor Semimembranosus Pork Muscles

Abstract

Curing meat products requires sodium nitrite to generate residual nitrite for preservation and development of a pink cured meat color. This study investigated the use of the essential amino acid L-arginine to activate the Nitric Oxide Synthase (NOS) in pre-rigor porcine muscle to evaluate the efficacy of this system in generating nitric oxide (NO) and residual nitrite (NOv2). Pre-rigor porcine Semimembranosus muscles were collected from four separate carcasses at six different harvest intervals (N=24). Varying concentrations of L-arginine solutions were applied to the pre-rigor muscle samples in tubes containing 0.9% NaCl and 576 ppm sodium erythorbate in deionized water, immersed for two hours, and transferred into separate tubes for stabilization. Cooked samples were cooked to 62C over one hour in a water bath. After stabilization the samples were homogenized, centrifuged, and frozen at -30C for three weeks and then analyzed for residual nitrite in raw, cooked, and cooked pellet samples, and curing efficiency in cooked samples. Raw L-arginine treated samples overall had higher (P<0.05) levels of residual nitrite at 32 mM (14.34 ppm) compared to the control (0 mM; 0.08 ppm). The cooked samples had less residual nitrite compared to the raw samples, suggesting that the NOS system converted the nitrite to NO to form the cured meat pigment nitrosylhemochromagen. The highest concentration of residual nitrite in the cooked pellets muscle samples occurred at 32 mM (15.69 ppm) L-arginine concentration. For curing efficiency and NO-hemochrome values no differences were found with respect to L-arginine concentration in the cooked supernatant samples. Differences (P<0.05) in total heme pigmentation were observed for 2 mM (24.22 ppm), 4 mM (34.17 ppm), 8 mM (70.38 ppm), 16 mM (20.14 ppm), and 32 mM (31.67 ppm) L-arginine concentrations compared to the control (0 ppm) but no significant differences between L-arginine concentrations were detected. The pellets of cooked samples analyzed for curing efficiency were highest at 32 mM (156.72%) and were significantly different (P<0.05) compared to the control (0.00%) and to other concentrations. This data suggests that the NOS system can generate NO and residual nitrite with the addition of L-arginine in pre-rigor porcine Semimembranosus muscle.