Growth of lactic acid bacteria (LAB) and lactobacilli was studied in Cheddar cheeses supplemented with live and heat-shocked Lactobacillus casei subsp. cosei L2A and with Neutrase@ to accelerate maturation. Bacterial counts of treated cheeses rapidly reached maximal values within 1 wk, whereas the control cheese reached comparable values only after 2 mo. Addition of 1.0% heat-shocked lactobacilli led to an excellent quality Cheddar cheese with a 50% increase in flavor development, as determined by sensory evaluation, compared to control cheese. Addition of Neutrase (1 x 1O-5 AU/g cheese) permitted a gain of an additional 10% while addition of higher concentrations (2 and 4x 10e5 AU/g cheese) resulted in undesirable bitterness.