Food preservation using ionizing radiation.

Irradiation processing has been researched extensively and is now in use worldwide for many food commodities. Irradiation has been successfully used to reduce pathogenic bacteria, eliminate parasites, decrease postharvest sprouting, and extend the shelf life of fresh perishable foods. Although food irradiation is widely accepted in world food markets, U.S. markets have been slower to accept the idea of irradiated food products. For fruits and vegetables, irradiation is not a cure for shelf life problems; cost and quality problems damage preclude its general use. It appears that the most likely use of irradiation in fruits and vegetables is as an insect control in those commodities for which there is no effective alternative method. For grains such as rice and wheat, irradiation has been used primarily to control insect infestation when insects have been shown to develop resistance to the traditional fumigation methods. Treatment of spices with irradiation doses of 10 kGy has proved to extend shelf life without causing significant changes in sensory or chemical quality. Higher doses that effectively sterilize spices, however, may cause undesirable chemical and sensorial changes. For meat, especially red meat, irradiation is considered a viable alternative in the effort to improve the safety of meat products. With time, the authors believe that economic realities and the technical superiority of irradiation for specific poultry products will lead to public acceptance of the process. Irradiation of seafood products is still being considered for approval by the USFDA, although it is currently used in Asian and European markets, especially for shrimp. It is our belief that scientifically based research in food irradiation and the positive results thereof will also prove economical in the twenty-first century. As we move to a more peaceful world with reduced threat of nuclear holocaust, these valid opinions will prevail and will overshadow the distortions and misinformation generated by the opponents of irradiation.

Radiosensitivity of Listeria monocytogenes Using Split Dose Application of Gamma Irradiation †.

The purpose of this study was to determine if split dose application of gamma radiation would alter the radiosensitivity of L. monocytogenes . Concentrations of 106 and 109 CFU L. monocytogenes per ml were suspended in tryptic soy broth and exposed to 0 to 5 kGy gamma radiation at 20, 4, and -80°C with equal split doses at 0- to 2-h time intervals (times between fractions, TBFs). Regression analyses of survival plots were used to calculate irradiation D values. Irradiation D values for split doses with 1- and 2-h TBFs were significantly lower than the control value and the values for 0.25- and 0.50-h TBFs (P < .05) at 20°C but this was not true at 4 or - 80°C With 1- and 2-h TBFs at 20°C the bacterium was near its generation time of 1.2 h, possibly accounting for the increased sensitivity. Results of this study indicated that split dose application increased the sensitivity of Listeria under certain conditions and that further investigation into this method is warranted.

Effect of environs and seasonality on metal residues in tissues of wild and pond-raised crayfish in southern Louisiana.

Two commercially important species of Louisiana crayfish, Procambarus clarkii (Girard) and P. acutus acutus (Girard), from the Atchafalaya River Basin, from open ponds and from the sediment and water of these environs were sampled three times during two consecutive fishing (production) seasons. The abdominal muscle and hepatopancreatic tissue were analyzed separately. Lead, mercury, and cadmium, if present, were in concentrations below the detection limit. In the hepatopancreatic tissue, barium was present in concentrations below 8 mg/kg, copper 11-15 mg/kg, and iron below 640 mg/kg. Abdominal muscle samples had less than 3 mg/kg of most metals. Locations with the highest levels of metal residues in sediment were not necessarily locations where crayfish had the highest levels in their tissues.

Decontamination of Campylobacter jejuni on chicken drumsticks using chemicals and radiation.

A trial was conducted to compare the efficacy of four disinfectants and radiation to reduce the level of C. jejuni contamination on poultry meat. Two levels of each treatment were applied to chicken drumsticks inoculated with a known concentration of a strain of Campylobacter jejuni, biotype 1, isolated from a human patient with diarrhea. Radiation using a cobalt-60 source at a level of 0.5 KGy effected a 99% surface reduction in C. jejuni. With a mean initial surface contamination level of 1.1 X 10(3) Colony Forming Units/cm2, 1 KGy completely eliminated C. jejuni. Glutaraldehyde at 0.5% concentration for 30 minutes had an efficacy similar to the lower dose of radiation. Chlorine showed a negligible effect on C. jejuni. Succinic acid and Poly (hexamethylenebiguanide hydrochloride) were statistically similar in their effectiveness, ranking between glutaraldehyde and chlorine. These results strongly indicate that, of the alternatives tested, low-dose radiation is the method of choice for reducing Campylobacter contamination of poultry products.