Showing 2 results for Raw Milk
H. Ezzatpanah, M. R. Ehsani, H. Lamea,
Volume 9, Issue 2 (7-2005)
Abstract
In this research some properties of the casein micelles in the raw and pasteurized milk were studied by electron microscopy. SEM and TEM were used to evaluate the differences in acidified casein micelles of raw and pasteurized milk at the Iso Electric Point (pH=4.6). Milk samples were taken from research pilot plant of The College of Agriculture. Milk was pasteurized by the L.T.L.T. method in the same pilot plant. The samples of raw and pasteurized milk were divided into two parts. One part of raw and pasteurized milk was acidified to the Iso Electric Point of caseins (pH=4.6) by lactic acid (9%) and then sample preparation for electron microscopy was done.
According to the previous findings, results indicated that in the native pH, specially in fresh raw milk casein micelles were in spherical and individual form with the smooth surface. Aggregated casein micelles were present of acidified samples of the raw and pasteurized milk. Aggregation was the result of neutralization of electric charges in the isoelectric pH of casein and partial removal of micellar calcium phosphate. Results of both electron microscope confirmed each other and effects of heating on increasing of the casein micelle size during pasteurization were seen.
M.r. Ehsani, H. Ezzat Panah, H. Lamea,
Volume 9, Issue 3 (10-2005)
Abstract
In this study changes in microstructure of casein micelles in raw and pasteurized milk were investigated by SEM and TEM. Milk was pasteurized by L.T.L.T. method (Temperature: 63 oC_ Time:30 minute).Samples of raw and pasteurized milk were taken from research pilot plant of The College of Agriculture. Each sample was divided into two parts. One part of each sample was directly prepared for SEM and TEM, whereas the second part were renneted at 2 oC and kept at this temperature for 24 h. and then prepared for evaluation by electron microscopes. Results indicated that in native state, particularly in raw milk casein micelles are in spherical shape with smooth surface and in the single form. The samples, which stored in the cold were under the effect of the rennet, encounter of filamentous status that might be due to the changes occurred in kappa-casein following the action of rennet along with partial removal of beta-casein and micellar calcium phosphate. Micrographs of casein micelles in pasteurized milk indicated that thermal condition during pasteurization had influenced on increasing of casein micelles size.
