Elimination of Listeria monocytogenes in salamín (Argentinean dry fermented sausage) by gamma irradiation

RAAD A.C. ; LIRES C. M. ; SOTERAS T.; HORAK C.; COVA M.C.; VAUDAGNA S. R.

Viena

Conferencia; Second International Conference on Applications of Radiation Science and Technology (ICARST-2021); 2021

IAEA

Listeria monocytogenes is one of the most frequently detected pathogens in dry fermented sausages and is very difficult to control it in the manufacture environment. This situation is especially critical in our country, due to Argentine Food Code (CAA) establishes a zero tolerance criterion for L. monocytogenes. Therefore, the local meat industry is looking for a new additional technology to ensure public health, to avoid the recall of these products and the consequent economic losses. Salamín (salami) is a dry fermented sausage, prepared with pork and beef minced flesh, with the addition of bacon (fat content about 30%), salt, sugar, spices and wine. To determine the minimum irradiation dose required to achieve a specific decontamination level in this product, the resistance of three strains of Listeria monocytogenes to gamma irradiation in salamín was investigated. Salami slices of 2,5 cm were inoculated with L. monocytogenes ATCC 15313 and with a pool of two wild serotype 1/2a, 1/2b to achieve initial loads of 108 C.F.U./g, then samples were vacuum-packaged and irradiated with doses of 0; 0.3; 0.6; 0.9 and 1.2 kGy. Irradiation was carried out at the semi industrial cobalt-60 facility at Ezeiza Atomic Centre, about 820 kCi of activity with dose rate of 6,5 kGy/h and a alanine/EPR as dosimetry system were used, traceable to NPL, UK. The decimal reduction doses (D10 value) for L. monocytogenes ATCC and wild pool strains were 0.75 kGy and 0.73 kGy, respectively. So, a minimum radiation dose (Dmin) of 4 kGy was selected to achieve 5 logarithmic reductions of L. monocytogenes in this product. A additional irradiation dose of 6 kGy (1.5 x Dmin) was selected. The sensorial attributes were also evaluated using a similarity triangular test (ISO 4120). It was performed with 42 panelists to assess differences among control and treated samples. For this purpose, whole salami samples were vacuum?packed, kept in an icebox at 4±0.5 °C and irradiated at doses of 0; 4 and 6 kGy at room temperature (20 °C). Samples were stored at 4 ºC until analysis, day 5 and 35 post irradiation, when were cut in 5 mm slices and kept at room temperature before serving. The assay was carried out under normalized conditions according to ISO 6658 and ISO 8589. Two triangular tests were carried out in different days, one for each storage time. At day 5 post irradiation significant differences (p0.05) were found among control and treated samples. Therefore, the irradiation treatment at 4 kGy to achieve a 5-log pathogen reduction in salami, combined with vacuum-packaging, would render a safe product with similar flavor to the non-irradiated one, after 35 days under refrigerated storage conditions. Nevertheless, additional analysis is needed for establishing more precisely the storage time at which the differences detected on day 5 are no longer noticeable.