he aim of this study was to determine the effects of different black cumin (Nigella sativa) concentrations on the characteristics of tulum cheese during ripening (at + 4 +/- 1 degrees C for 90 d). Increasing levels of black cumin decreased dry matter and fat contents (p < 0.05). Titratable acidity increased slightly with addition of black cumin in the samples. Ripening index (water soluble nitrogen/total nitrogen; WSN/TN, %), nonprotein nitrogen (trichloroacetic-soluble nitrogen/total nitrogen; TCA-SN/TN, %), amino nitrogen (phosphotungstic acid-soluble nitrogen/total nitrogen; PTA-SN/TN, %) and lipolysis levels, histamine and tyramine contents increased continuously during ripening. Lipolysis increased significantly with black cumin concentration (p < 0.05). The addition of black cumin decreased histamine and tyramine contents of the cheeses (p < 0.05). Total aerobic mesophilic bacteria as well as yeast and mould counts of the samples ranged from 10(5) to 10(3) cfu/g. Coliforms and Staphylococcus aureus were not detected in any of the samples during ripening. Lactobacilli, lactococci and enterococci were the dominant groups of bacteria. Increasing levels of black cumin in cheeses significantly decreased other microorganisms (except lactobacilli, lactococci tion of 1 % black cumin improved body and texture properties in the sensory evaluation of tulum cheese while higher black cumin concentrations had a negative effect on the sensory properties, resulting in dark appearance and bitter taste.