Survival of Listeria monocytogenes inoculated in retail soymilk products

The consumption of soymilk products has been growing; because these foods contain proteins and isoflavone, and lack of lactose and cholesterol. The survival and growth of Listeria monocytogenes in the soymilk products were investigated by inoculating Listeria monocytogenes into various retail soymilk products which claimed to improve or fortify the functional properties. The results show that the refrigeration cannot successfully prevent the growth of Listeria monocytogenes in soymilk products. The addition of fiber content and higher viscosity in soymilk may significantly inhibit the growth of L. monocytogenes at 4–7 °C; however, this phenomenon was not observed when the incubation temperature was elevated to 22 °C. The change of pH value and TTS (total soluble solids) in soymilk products owing to L. monocytogenes, especially those with rich fiber content, might be negligible for the public. Thus the possible contamination of L. monocytogenes to soymilk products should be of crucial concern.