Influence of milk centrifugation, brining and ripening conditions in preventing gas formation by Clostridum spp. in Gouda cheese

This study examined milk centrifugation, increased salt concentration, and low ripening temperature as potential strategies to prevent late blowing ca used by gas-forming Clostridium spp. in Gouda cheese. The survival of clost ridia spores in cheese brine and their ability to enter Gouda cheese during brining was also evaluated. Centrifugation (3000 x g for 30 s) of contamin ated milk resulted in > 60% spore reduction, with increased spore reduction at greater centrifugal forces. Low levels of C. tyrobutyricum and C. sporo genes spores survived in saturated (23%, w/v) brine with 2% (v/v) added whe y at 15 degrees C for 63 days, while C. beijerinckii and C. butyricum spore s were not detectable on days 4 and 35, respectively. Spores of C. tyrobuty ricum in brine infiltrated Gouda cheese during 2 h of brining at 13 degrees C resulted in production of small gas holes during ripening. In Gouda chee se slurry stored at 13 degrees C, three C. tyrobutyricum strains plus one o f three C. sporogenes strains germinated in the slurry with no added salt. Of three C. tyrobutyricum strains stored at 13 degrees C in slurries with h igher water-phase salt concentrations of 2.4 and 3.6%, two strains and one strain germinated, respectively. No germination of spores was detected in a ny cheese slurry stored at 5 or 8 degrees C. Milk centrifugation, increased percent water-phase sail: absence of spores in brine, and decreased ripeni ng temperature are all potentially important measures against gas productio n by Clostridium spp, in Gouda cheese. (C) 2000 Elsevier Science B.V. All r ights reserved.