Transmission Electron Microscopic Imaging of Casein Submicelle Distribution in Mozzarella Cheese

Abstract

Microscopic imaging anal. was used to compare casein submicellar structure in Mozzarella cheese on the day of stretching and after 6 wk of storage at 4.degree.C. Cheeses contg. 8.5-9.3% fat and 56.6-59.7% moisture were prepd. with four different coagulants. Images of thin sections of cheese were electronically enhanced to increase contrast resoln., and spacings between electron dense regions were estd. from radial distribution plots of Fast Fourier Transforms. Binary images derived from digital images were integrated to obtain total areas of electron d. During storage, submicelles in each cheese formed larger aggregates with fewer cross links at longer av. spacings. There were no significant differences in total electron d. between the cheeses, indicating that the submicelles rearranged with time. Reorganization of submicelles was related to changes in rheol. properties and decreases in percentage of intact alpha-sl-casein.