The use of viable or attenuated Lactobacillus helveticus DPC 4571 for use in enzyme-modified cheese production was assessed. Optimal heat shocking conditions for attenuation of DPC 4571 were found to be 69 degrees C for 25 sec. Enzyme-modified cheese was produced from an emulsion of pre-hydrolysed rennet curd, water, and butter fat. This substrate was heat-treated and inoculated with either an equivalent level of viable or attenuated cells of DPC 4571 and further incubated under controlled conditions. The heat-treated products produced using attenuated DPC 4571 had a preferred sensory character with strong cheesy savory notes, enhanced secondary proteolysis, and more key volatile flavor compounds than those produced with viable DPC 4571. However, prolonged incubation (>16 h) resulted in growth of advantageous enterococci, which adversely influenced the sensory profile.