title: Elimination of Escherichia coli O 157 : H7 and Listeria monocytogenes from raw beef sausage by gamma-irradiation.
abstract: The effectiveness of low gamma-irradiation doses in the destruction of Escherichia coli O 157 : H7 and Listeria monocytogenes in raw beef sausages was investigated. Raw samples of fresh manufactured beef sausage were subjected to gamma-irradiation at doses of 0, 1, 2, and 3 kGy. Then samples were cold-stored (4 +/- 1 degrees C) for 12 days and the effects of irradiation and storage on the counts of these harmful bacteria were studied. Moreover, the effects of irradiation and storage on the percentages of free fatty acids (FFAs) in lipids, on the p-anisidine values of lipids, solubility of sarcoplasmic and myofibrilar proteins, and water-holding capacity (WHC) were also determined. The results showed that gamma-irradiation at 1 and 2 kGy significantly reduced the counts of E. coli O 157 : H7 and L. monocytogenes, while 3 kGy dose effectively eliminated these bacteria by more than 4 log and 3 log units, respectively, and could keep their counts below the detection level during storage. Gamma-irradiation had no significant effects on the percentages of FFAs in lipids, solubility of sarcoplasmic and myofibrilar proteins, and WHC of samples, while it significantly increased the p-anisidine value of lipids. During storage, significant increases in the percentages of FFAs and p-anisidine values were observed for lipids of irradiated and nonirradiated sausages, while the solubility of sarcoplasmic and myofibrilar proteins showed no significant changes. Moreover, samples of irradiated and nonirradiated sausages showed significant decreases in their WHC during the first 6 days of storage at 4 +/- 1 degrees C, then showed no significant changes. Finally, gamma-irradiation at a dose of 3 kGy appeared to be sufficient to improve the microbiological safety of raw beef sausages without adverse effects on their chemical properties.
authors.affiliation: Atomic Energy Authority, Nuclear Research Center, Abou Zaabal, Egypt. heshambadr_aea@yahoo.co.uk
authors.forename: Hesham M
authors.initials: HM
authors.lastname: Badr
mesh_terms: D000818:Animals; D002417:Cattle; D003080:Cold Temperature; D019453:Escherichia coli O157 / Q000302:isolation & purification / Q000528:radiation effects*; D005230:Fatty Acids, Nonesterified / Q000032:analysis; D005514:Food Irradiation; D005519:Food Preservation; D005720:Gamma Rays; D015227:Lipid Peroxidation; D008089:Listeria monocytogenes / Q000302:isolation & purification / Q000528:radiation effects*; D008461:Meat Products / Q000032:analysis / Q000382:microbiology*; D009124:Muscle Proteins / Q000737:chemistry; D009210:Myofibrils / Q000737:chemistry; D012519:Sarcoplasmic Reticulum / Q000737:chemistry; D012995:Solubility
chemical_list: D005230:Fatty Acids, Nonesterified; D009124:Muscle Proteins