A real-time PCR system was used to differentiate between the common spoilage yeasts, Zygosaccharomyces bailii, 2 Zygosaccharomyces rouxii, Candida krusei, Rhodotorula glutinis and Saccharomyces cerevisiae, based on melting peak T. analysis of the 5.8S rDNA subunit and the adjacent ITS2 region of these yeasts. By using the real-time PCR system and by targeting the citrate synthase (cs 1) gene of C. krusei, it was possible to develop a sensitive detection system to both identify and quantitate the level of C. krusei growth in an artificially contaminated apple juice sample. (C) 2003 Elsevier B.V. All rights reserved.