The heat resistance of three Saccharomyces cerevisiae strains isolated from spoiled peach puree, in McIlvaine buffer (pH 4 and 7) and peach puree (pH 3.9) was studied. The D60-values in buffer at pH 7 were 0.75, 1.32 and 0.14 min for the strains 173, 180 and 325, respectively. The pH of the buffer did not influence the heat resistance of the three strains studied. The thermal sensitivity for all strains assayed was higher when peach puree was used with D60-values of 0.53, 0.20 and 0.10 min for the strains 173, 180 and 325, respectively. The menstrua used had limited influence on the z-values, varying between 3 (strain 173, pH 4) and 4 (strain 325, peach puree).