The starter grows during Cheddar cheese manufacture from ~10^7 to 10^8-10^9 cfu/g and reduces the pH from that of milk (~6.7) to ~5.4 at the point of milling. Since Cheddar is a dry-salted variety, and unlike many other cheeses, acidification must be close to complete at the end of manufacture and before salt addition. Salt-in-moisture levels increase rapidly in Cheddar due to the large surface area of the curd chips.
During the early stages of ripening, viable starter counts decrease rapidly at a strain-dependent rate. This decline is due to the unfavourable conditions in cheese for the growth and survival of lactococci: low pH, high concentration of NaCl and lack of fermentable carbohydrate. The salt-in-moisture level largely determines the rate of utilisation of residual lactose in the cheese which is of significance to cheese quality.
After death, the lactococci lyse at a rate that is strain dependent and contribute many important enzymes to cheese ripening (particularly its battery of peptidases but also esterases). There is evidence emerging that starter cells may be metabolically active but non-culturable during ripening and that they may contribute to amino acid catabolism in that state.
Courses in Cheese Science
Graduate-level courses (6-24 h) on cheese science with an emphasis on the biochemistry of cheese ripening are available are available to companies, universities and research institutes worldwide.
- Cheese Problems Solved (McSweeney, ed., 2007)
- Advanced Dairy Chemistry-3. Lactose, Water, Salts and Minor Consitiuents (McSweeney, Fox, eds., 2009)
- Advanced Dairy Chemistry-2. Lipids (Fox, McSweeney, eds., 2006)
- Advanced Dairy Chemistry-1. Proteins (Fox, McSweeney, eds., 2003)
- Cheese: Chemistry, Physics and Microbiology. Vol. 2. Major Cheese Groups (Fox, McSweeney, Cogan, Guinee, eds., 2004)
- Cheese: Chemistry, Physics and Microbiology. Vol. 1. General Aspects (Fox, McSweeney, Cogan, Guinee, eds., 2004)
- Fundamentals of Cheese Science (Fox, Guinee, Cogan, McSweeney, 2000)
- Dairy Chemistry and Biochemistry (Fox and McSweeney, eds., 1998)