|M.Sc Student||Shufrin Marina|
|Subject||The Effect of Physical and Biochemical Treatments on the|
Allergenic Activity of Milk Proteins
|Department||Department of Biotechnology and Food Engineering||Supervisors||Professor Emeritus Uri Cogan|
|Professor Emeritus Shmuel Yannai (Deceased)|
Milk allergy is a common adverse food reaction. Strict avoidance of the allergy-causing food is essentially the only way to prevent a reaction. In our study, we investigated the effect of ohmic heating (120 and 1500C), shock wave treatment (10 pulses) and proteolytic (pepsin, trypsin) digestion on the allergenicty of milk proteins.
Both physical treatments caused a partial reduction of allergenicity of milk proteins. Ohmic heating (at 1500C) showed the best results of decreasing milk proteins allergenicity, achieving ~ 70% reduction of the allergenic potential of the whey proteins b-lactoglobulin and a-lactalbumin. Shock wave treatment resulted in a lower effect.
Based on electrophoresis and rate of sedimentation, it appears that only the secondary and tertiary structures of the proteins were modificated and that the primary structure was unchanged. Hence, during the physical treatments, the native structure and many conformational epitopes of these proteins may be modified, leading to the elimination of IgE binding capability to conformational epitopes.
We successfully sensitized Brown Norway (BN) rats by intraperitoneal injections, but oral exposure to the same proteins did not cause IgE production. Possible explanation: commercial feed used contained trace amounts of milk proteins that led to development of the tolerance of the rats. In the case of proteolytic digestion, rat sensitization with the resulting peptides, obtained from b-lactoglobulin and b-casein, resulted in complete elimination of the immunoresponse. It would seem that all epitopes were destroyed, but ELISA showed that intact b-lg/ a -casein sIgE reacted with the digested b-lg/a-casein. This interaction indicates that linear epitopes are still present in the digested peptides.