ANTIMICROBIAL ACTIVITY OF PELARGONIUM ESSENTIAL OILS ADDED TO A QUICHE FILLING AS A MODEL FOOD SYSTEM

Eight essential oils obtained by steam distillation from the scented l eaves of Pelargonium species and cultivars mere added at 250, 500 and 1000 ppm to a quiche filling, inoculated with either Saccharomyces lud wigii or Zygosaccharomyces bailii (at 10(8) cfu g(-1)), Salmonella ent eriditis or Listeria innocua (at 10(9) cfu g(-1)). The quiche fillings were then kept at 25 degrees C for 24 h and the residual number of mi cro-organisms determined using the pour plate technique. There was an effective antimicrobial activity by the Pelargonium essential oils at 250 ppm, comparable with that of commercial thyme oil, an excellent an timicrobial agent, against Saccharomyces ludwigii and Zygosaccharomyce s bailii, and a lesser inhibition compared with commercial thyme again st Salm. enteriditis. There was a greater diversity of activity agains t L. innocua, which was in some cases more effective than commercial t hyme oil. At 500 ppm, there was a greatly increased inhibition of micr obial growth using the Pelargonium essential oils, which was comparabl e with that of commercial thyme, clove, geranium and coriander oils. A s there is no evidence for the toxicity of any of these novel Pelargon ium oils, and their odour does not make the delicately flavoured quich e filling unpalatable, there is a strong potential for their use in fo od processing.