IMPACT OF IRRADIATION ON THE MICROFLORA OF MEAT FOR THE PRODUCTION OF FERMENTED SAUSAGE, EFFECT OF RADIOLYTIC PRODUCTS ON BACTERIA IN A FOOD SYSTEM AND A NEW METHOD FOR THE ENUMERATION OF RADIATION-RESISTANT, NON-SPORE-FORMING BACTERIA

Fermented sausage was prepared from irradiated sausage batter. Doses up to 500 Krad reduced the total aerobic bacteria by as much as 4 log cycles. Irradiation substantially reduced the coliform and staphylococci counts, and these bacteria did not reach levels that indicated public health concern even after fermentation. These reductions allowed the use of a lower inoculum and a longer fermentation. Irradiation of sausage preblends reduced the total aerobic population and extended the safe storage time.;Inhibitory effects of radiolytic products were studied using radiation-sensitive and radiation-resistant bacteria. End products of a 300 Krad dose completely inhibited the resistant bacteria on an experimental medium, while radiation-sensitive bacteria could tolerate products generated by a 1000 Krad dose. No inhibition of either group of bacteria could be observed on fresh meat irradiated with 1500 Krad. The inhibitory effects of radiolytic products in culture media could be overcome by the addition of catalase or sodium pyruvate.;A method was developed to enumerate radiation-resistant vegetative bacteria while eliminating spore-forming bacteria. Multiple irradiation doses combined with intervals of incubation were found to produce a maximum reduction in spore formers with a minimum reduction in resistant vegetative bacteria.;Ground beef was irradiated in either a refrigerated or frozen state and then stored at refrigeration temperatures for 14 days. Several groups of bacteria were monitored during storage to determine the nature of the spoilage flora. The ultimate spoilage flora of the irradiated samples consisted of Gram-positive, nonlactic psychrotrophs, with relatively few differences between the two irradiation conditions. Coliform bacteria were evaluated as indicator organisms for wild-type salmonellae in irradiated ground beef. Salmonellae were not isolated in samples which were free of coliforms.