MICROSTRUCTURE AND PHYSICAL-PROPERTIES OF A REDUCED FAT MOZZARELLA CHEESE MADE USING LACTOBACILLUS-CASEI SSP CASEI ADJUNCT CULTURE

Reduced fat Mozzarella cheese was produced using Streptococcus thermop hilus and Lactobacillus helveticus and either total or partial replace ment of L. helveticus with Lactobacillus casei ssp. casei Stretch, mel t and cook colour were determined at 1, 7, 14, and 28 d. All cheeses d ecreased in stretch during the first 7 d of storage, bur there were no significant differences between culture types. Reduced fat cheese mad e with L. helveticus and S. thermophilus showed the greatest stretch a t both 1 and 7 d. After 14 d, all cheeses showed the same level of str etch. Storage time significantly affected stretch and melt. All reduce d fat cheeses showed less melt through 14 d than the control cheese. R educed fat cheese made with partial or total replacement of L. helveti cus with L. casei ssp. casei had more stretch and less cook colour at day 1 than the part-skim Mozzarella. At 28 d of storage, all cheeses s howed the same levels of melt and stretch with the reduced fat cheeses having less cook colour. Both scanning and transmission electron micr oscopy showed substantial differences between reduced fat and part-ski m Mozzarella cheese during the manufacturing process. Reduced fat Mozz arella had a much more dense protein matrix with fewer small vacuoles (voids left in the cheese upon removal of fat with chloroform, particu larly after stretching). TEM showed that after set, the reduced fat ch eese had much larger protein strands where casein micelles had formed dense aggregates. Overall, the physical properties of reduced fat Mozz arella cheese made in this study, including those made with the L. cas ei culture adjunct, compared favourably to part-skim Mozzarella cheese made with conventional thermophilic cultures.