Frankfurter-type sausages were prepared with potassium lactate, sodium diacetate and various levels of a mixture of potassium lactate and sodium diacetate. The development of Lactobacillus sake and Listeria monocytogenes and the sensory quality were compared with a reference product without any of these additions. It was shown that addition of 2-3% of a solution, containing a mixture of 56% potassium lactate and 4% sodium diacetate to Frankfurter-type sausages inhibited the development of L. sake and L. monocytogenes bacteria inoculated on to the product during storage at 4°C. L. sake bacteria were mainly inhibited by the addition of lactates and its water activity lowering effect, resulting in a shelf-life extension with 75-125%. In Frankfurter sausage with 0.1% sodium diacetate L. sake was not inhibited, but the development of L. monocytogenes was retarded. The increase of L. monocytogenes also slowed down when L. sake numbers reached 108cfug-1, probably as a result of lactic acid and/or bacteriocins production in those products. A synergistic effect of the combined addition of lactate and diacetate was observed at the end of the shelf-life, where L. monocytogenes was inhibited in Frankfurters with mixtures of potassium lactate and sodium diacetate while some growth was observed in products only containing potassium lactate. Sensory properties of the product were not significantly influenced by the addition of 2-3% of solutions containing a potassium lactate/sodium diacetate mixture. © 2002 Elsevier Science Ltd. All rights reserved.