The Comparison of Immunoglobulin Level in the Raw and Fresh Milk

MEI-YING LIU SI-TSE JIANG* AND CHENG-CHIN HSU

Institute of Nutritional Science, Chung Shan Medical & Dental College
School of Medical Technology*, Chung Shan Medicl & Dental College

ABSTRACT

   In addition to analysis of the immunoglobulin concentration in milk by traditional sandwich enzyme-linked immunosorbent assay methods,we have further observed the difference of the immunoglobulin concentration between the raw and fresh milk. Protein of untreated raw milk, provided by the milk plant of Tunghai University, and commercial fresh milks were separated by ammonium sulfate precipitation. The variances of proteins between raw and fresh milk were compared by using SDS-polyacrylamide electrophoresis. The results showed by comparing the bands that there was a difference in immunoglobulin G between the raw and the fresh milk. The bovine immunoglobulin G of the raw milk was further isolated and purified. A monospecific antiserum was prepared. The technology of sandwich ELISA was conducted to analyze and observe the difference of immunoglobulin concentrations between raw and fresh milk. Raw milk contained 140.73±16.99 ug/ml and that varied from 0.16±0.017 ug/ml to 0.28±0.04 ug/ml in fresh milk. The content of immunoglobulins might be one of the indicators to evaluate heat treatment of milks.

Key words: Immunoglobulin G, sodium-dodecyl sulfate-polyacrylamide gel electrophoresis,SDS-PAGE, enzyme-linked immunosorbent assay, LISA