Evaluation of modified atmosphere packaging with carbon monoxide for fresh ground pork, fresh pre-rigor pork sausage and fresh post-rigor pork sausage

Fresh ground pork, fresh pre rigor pork sausage and post rigor pork sausage patties were manufactured in the Iowa State Meat Laboratory and placed individually in either modified atmosphere packaging (MAP) bags with 0.4% carbon monoxide (CO) and 99.6% carbon dioxide (CO2) or over-wrapped with oxygen permeable film on foam trays (OW), and stored at 2-40C under fluorescent lights for up to 31 days. Aerobic plate counts, anaerobic plate counts, psychrotrophic plate counts, raw and cooked color, purge and lipid oxidation were measured for all three products. Sensory evaluation was performed with a trained panel for the fresh ground pork and post-rigor pork sausage. Results indicated that the ground pork, pre-rigor pork sausage and post-rigor pork sausage in MAP had lower aerobic and psychrotrophic plate counts and reduced rate of lipid oxidation throughout storage (P\u3c0.05). All three products in MAP were lighter (high L* value) than the OW patties in both the raw and cooked color measurements, and all three products in MAP were redder than the OW patties in the raw color (p\u3c0.05). The pre-rigor pork sausage in MAP, however, was the only product that was significantly redder than the other two products in MAP and OW in cooked form (p\u3c0.05). Sensory evaluation showed no differences in packaging type or product type for pork aroma, sour-like aroma, off-aroma, firmness, juiciness, pork flavor, sour flavor, and off-flavor in both cooked products and no differences in sausage/spice aroma in both raw products (p\u3e0.05). Significance was shown in both raw products in MAP for sour-like aroma and cherry red color, and for both cooked products in MAP for red and brown color (p\u3c0.05). An increased amount of purge, increased amount of anaerobic growth, and cooking defect like fluffing also was observed in the products in MAP throughout the storage (p\u3c0.05). In conclusion, MAP, with a combination of CO and CO2, extended the shelf life of fresh ground pork, pre-rigor pork sausage and post-rigor pork sausage by reducing microbial growth and improving quality attributes, particularly color, compared to conventional OW packaging