AGE-RELATED-CHANGES IN THE MICROSTRUCTURE OF MOZZARELLA CHEESE

Changes that occurred in the microstructure of low-moisture, part skim Mozzarella made with a mixed starter consisting of Streptococcus sali varius ssp. thermophilus and Lactobacillus delbrueckii ssp. bulgaricus and coagulated with fermentation-produced chymosin, were examined dur ing 50 days of ripening at 4-degrees-C. Immediately after manufacture (day 3), a homogeneous and continuous phase of amorphous paracasein re presented a three-dimensional protein network in the cheese. A large n umber of irregularly shaped and sized microcavities were present. Duri ng 50 days of aging, an increase in the porosity of the defatted parac asein matrix was apparent. These changes were coincidental with a four fold increase in water-soluble nitrogen (from approximately 2 to 8 % o f total N) and hydrolysis of approximately 50 % of alpha(s1)-casein. I t is suggested that the confluence of adjoining microcavities that occ urred progressively throughout storage may be due to proteolysis or CO 2 production by the starter culture.