Immunoelectron microscopic observation of β-lactoglobulin in paneer cheese using the Tokuyasu method

Takamichi Kamigaki, Tomohito Hanazawa, Yoshiko Ito, Yuri Nishino, Atsuo Miyazawa
2019 Milk Science  
Immunoelectron microscopy is a useful electron microscopy observation method for dairy product analysis to determine the localization of speciˆc proteins. We conˆrmed the usefulness of the Tokuyasu method (frozen ultrathin section method) by visualizing the distribution of b-lactoglobulin in a paneer cheese sample obtained by acid coagulation after heating raw bovine milk. In the control test (post-embedding method), as the protein was ˆxed only with paraformaldehyde, the milk protein
more » ... were not continuous and most fat globules ‰owed out. In the Tokuyasu method, limited lipid out‰ow occurred, and continuous milk protein aggregates containing many cavities and spherical fat globules were observed. The fat globules formed aggregates with milk proteins, and colloidal gold-labeled b-lactoglobulin antibody was adsorbed to surround these aggregates. Colloidal gold-labeled b-lactoglobulin antibody was also adsorbed on the fat globule surface in the cavities. These results showed the possibility of evaluating not only the milk protein aggregates, but also the state of milk protein adsorbed on the fat globular surface. Accordingly, the Tokuyasu method is expected to be suitable for various dairy products containing lipids and has been shown to be applicable to improving characteristics such as physical properties and texture.
doi:10.11465/milk.68.94 fatcat:4e3qzspkufgu7hwf6o34ojghmq