Electrical conductivity as a tool for analysing fermentation processes forproduction of cheese starters

Electrical conductivity was used for characterizing the production of chees e starters on pilot and industrial scales. The variation of pH and conducti vity with time was followed during growth of cultures used for Cheddar chee se production. Pilot-scale fermentations were carried out in triplicates wi th eight mesophilic mixed cultures, without pH control and mixing, in recon stituted milk. Industrial fermentations were performed for four of the eigh t starters with similar operating conditions. The first derivatives of pH a nd conductivity with time were calculated numerically from neural network m odels and several kinetic parameters were identified, specifically maximum acidification and conductivity rates of change (V-m, VG(m)) with correspond ing times, and the pH and conductivity at which V-m and VG(m) occurred. The conductivity was shown to be an adequate measurement for providing valuabl e information on the course of the fermentation process and the starter act ivity on the two production scales. (C) 2000 Elsevier Science Ltd. All righ ts reserved.