ABSTRACT: Bifidobacterium longum 1941, B. animalis subsp. lactis LAFTI ® B94, Lactobacillus casei 279, Lb. casei LAFTI L26, Lb. acidophilus 4962, or Lb. acidophilus LAFTI L10 were used as an adjunct in the production of Cheddar cheeses, which were ripened at 4 and 8 °C for 24 wk. Effects of ripening temperatures and probiotic adjuncts on proteolysis and sensory evaluation of the cheeses were examined. Higher ripening temperature increased the level of proteolysis in the cheeses. Product of proteolysis and organic acids released during ripening were shown to be important for the flavor of Cheddar cheeses. There were positive and significant correlations between the levels of soluble nitrogen, lactic, acetic, and butyric acids, percentage hydrolysis of α s1 ‐CN and β‐CN to the scores of cheddary flavor ( P < 0.05). Scores for sour‐acid and vinegary flavors were higher in cheeses with the addition of Bifidobacterium sp. or Lb. casei 279 ripened at 8 °C. The scores were positively and significantly correlated to the level of lactic, acetic, and free amino acids in the cheeses ( P < 0.05). The results show that both 4 and 8 °C have potential for use in the ripening of probiotic Cheddar cheeses.