Methods for the detection of Alicyclobacillus acidoterrestris at a level of 1 cell per 100 ml and enumeration with a sensitivity of 5 cells ml-1 were developed. Spores of A. acidoterrestris survived pasteurization and outgrew and multiplied at a similar rate to vegetative cells in both orange juice and apple juice. Alicyclobacillus acidoterrestris grew readily in orange juice, apple juice and a non-carbonated fruit juice-containing drink at temperatures of 25-44 degrees C producing a taint and elevated levels (1-100 ppb) of guaiacol. Isolates of A. acidoterrestris can be identified using the DuPont RiboPrinter. It was isolated from apple drinks, apple juice concentrate and freshly squeezed orange juice.