Effects of modified Lactobacillus helveticus 6024 by using heat-shock treatment on its biochemical properties and Cheddar cheese ripening were investigated. Results showed that the cell acidification activity was only 6.4% at 6 h cultivation when cells were subjected to the heat treatment of 10 s at 70℃. However, the average level of aminopeptidase activity is maintained at around 25%. The cheese chemical compositions were not apparently affected by adding the heat-shock cells, but the levels of soluble nitrogen were found to be different. The level of WSN% was not significantly different between experimental cheese and control, and there was a 2-fold increase in the level of 5% PTA-SN% at 3 months ripening when compared to control (not adding the heat-shock cells). The results of TPA profiles and microstructure also indicated that the ripening of Cheddar cheese is accelerated as a result of the heat-shock cells. 