Effect of selected generally recognized as safe preservative sprays on growth of Listeria monocytogenes on chicken luncheon meat

The ability of selected generally recognized as safe (GRAS) chemical preservatives to reduce populations or inhibit growth of Listeria monocytogenes on chicken luncheon meat was evaluated. Slices of luncheon meat were treated by evenly spraying onto their surfaces 0.2 ml of a solution of one of four preservatives (sodium benzoate, sodium propionate, potassium sorbate, and sodium diacetate) at one of three different concentrations (15, 20, or 25% [wt/vol]). Each slice was then surface inoculated with a five-strain mixture of 10(5) CFU of L. monocytogenes per ml, held at 4, 13, or 22degreesC, and assayed for L. monocytogenes immediately after inoculation and at 3, 7, 10, and 14 days of storage. Initial reductions of L. monocytogenes populations ranged from 0.78 to 1.32 log(10) CFU g(-1) at day 0 for sodium benzoate- or sodium diacetate-treated meat, whereas reductions for the sodium propionate oz potassium sorbate treatments were only 0.14 to 0.36 log(10) CFU g(-1). After 14 days of storage at 4degreesC. L monocytogenes populations on all treated slices were 1.5 to 3 log(10) CFU g(-1) less than on the untreated slices. At 13degreesC and after 14 days of storage, L. monocytogenes populations were 3.5 and 5.2 log(10) CFU g(-1) less on luncheon meat slices treated with 25% sodium benzoate or 25% sodium diacetate, respectively, and ca. 2 log(10) CFU g(-1) less when treated with 25% sodium propionate or 25% potassium sorbate than on untreated control slices. Only sodium diacetate was highly inhibitory to L. monocytogenes on meat slices held at 22degreesC for 7 days or longer. Untreated luncheon meat held,it 22degreesC was visibly spoiled within 10 days, whereas there was no evidence of visible spoilage on any treated luncheon meat at 14 days of storage.