No abstract

The effects of irradiation dose (0,0.5 and 1.0 kGy), headspace oxygen (0, 10 and 20% 02, balance nitrogen) and storage temperature (5, 15 and 25°C) on the physical, chemical and sensory changes in fresh pork were studied using factorial design experiments. Irradiation in the absence of oxygen extended the sensory shelf life of pork from 9 to 26 days at 5°C and from < 2 to 2 days at 25°C. Oxygen in the package headspace combined with irradiation adversely affected physical, chemical and sensory characteristics of the end product.

The combined effect of three initial levels of oxygen (0, 10, and 20%), irradiation dose (0, 0.5, and 1 kGy), and storage temperature (5, 15, and 25°C) on toxin production by Clostridium botulinum in inoculated modified atmosphere packaged pork were investigated using factorial design experiments. Toxin was detected after only 2 d in all treatments stored at 25°C. At 15°C, irradiated and nonirradiated product packaged with 10 or 20% headspace oxygen were toxic after 14 d. For product packaged with 0% oxygen and an oxygen absorbent, toxin was detected after 21 d in nonirradiated samples compared to 43 d for product treated with an irradiation dose of 1 kGy. No toxin was detected in any product stored at 5°C, even after 44 d. Headspace oxygen in product initially packaged with 20% oxygen decreased to 0.1% after 14 d at 15°C and to ≤3% after 5 d at 25°C, with a concomitant increase in package headspace CO2 to 25–40%. For product packaged with 0% O2 and an oxygen absorbent, oxygen remained at ≤2% throughout the storage trial, while CO2 increased to 10 and 24% for nonirradiated and irradiated samples, respectively. Initial packaging of product with O2 appeared to enhance toxin production by C. botulinum in product stored at 15°C, probably as a result of increased CO2 enhancing spore germination.