Microstructure and Physical Properties of a Reduced Fat Mozzarella Cheese Made Using Lactobacillus caseissp. caseiAdjunct Culture

Abstract

Reduced fat Mozzarella cheese was produced using Streptococcus thermophilusand Lactobacillus helveticus, and either total or partial replacement of L. helveticuswith Lactobacillus caseissp. casei. Stretch, melt and cook colour were determined at 1, 7, 14, and 28 d. All cheeses decreased in stretch during the first 7 d of storage, but there were no significant differences between culture types. Reduced fat cheese made with L. helveticusand S. thermophilusshowed the greatest stretch at both 1 and 7 d. After 14 d, all cheeses showed the same level of stretch. Storage time significantly affected stretch and melt. All reduced fat cheeses showed less melt through 14 d than the control cheese. Reduced fat cheese made with partial or total replacement of L. helveticuswith L. caseissp. caseihad more stretch and less cook colour at day 1 than the part-skim Mozzarella. At 28 d of storage, all cheeses showed the same levels of melt and stretch with the reduced fat cheeses having less cook colour. Both scanning and transmission electron microscopy showed substantial differences between reduced fat and part-skim Mozzarella cheese during the manufacturing process. Reduced fat Mozzarella had a much more dense protein matrix with fewer small vacuoles (voids left in the cheese upon removal of fat with chloroform, particularly after stretching). TEM showed that after set, the reduced fat cheese had much larger protein strands where casein micelles had formed dense aggregates. Overall, the physical properties of reduced fat Mozzarella cheese made in this study, including those made with the L. caseiculture adjunct, compared favourably to part-skim Mozzarella cheese made with conventional thermophilic cultures.