The TPC of all treatment samples increased much slower than that of the control, corresponding with the result of headspace CO2. Despite the inclusion of OS, the microbial growth proceeded during the lag time for OS to eliminate headspace O2 to below 0.01%, and continued to survive on O2 occluded in the large number of pores in the cake matrix. Once the available O2 became limited, the microbial growth slowed down.