Antimicrobial activities of free and nano-dispersed (ND) thymol used at overall thymol concentrations of 0.3, 0.5, and 1.0 g/liter in apple cider adjusted to pH 5.5, against Listeria monocytogenes strains Scott A (A) and 101 (B) at 32°C. Error bars represent standard deviations of the means from four measurements, two from each of two replicates. ND thymol: , 0.3 g/liter; ○, 0.5 g/liter; □, 1 g/liter. Free thymol: +, 0.3 g/liter; △, 0.5 g/liter; ×, 1 g/liter. Control: ♢, bacterial culture with no thymol.