The sensory properties of probiotic Cheddar cheeses made using Lactobacillus acidophilus 4962, Lb. casei 279, Bifidobacterium longum 1941, Lb. acidophilus LAFTI (R) L10, Lb. paracasei LAFTI (R) L26 or B. lactis LAFTI (R) B94 were assessed after ripening for 9 months at 4 degrees C. Probiotic cheeses except those with Lb. acidophilus 4962 were significantly different (P < 0.05) from the control without any probiotic organism. Acceptability of probiotic cheese with Lb. casei 279 was significantly lower (P < 0.05) than that of the control cheese with bitterness and sour-acid taste as the major defects. Concentration of acetic acid in probiotic cheeses was higher (P < 0.05) than the control cheese. Vinegary scores did not influence the acceptability of the cheeses (P > 0.05). Increased proteolysis in probiotic cheeses did not influence the Cheddary attribute scores (P > 0.05). There were positive correlations (P < 0.05) between the scores of bitterness and the level of water-soluble nitrogen. (C) 2007 Elsevier Ltd. All rights reserved.