After thawing at room temperature, milk samples were well suspended, diluted 1 in 4 in distilled water, and centrifuged for 5 sec. at 200 g in a table top centrifuge. The lower phase containing the defatted whole milk was removed from the upper lipid layer into a new tube and diluted with 2 volumes of distilled water. Then one volume of a 46 concentrated protein sample buffer was added. To separate the whey and casein fractions, defatted whole milk was spun for 15 min. at 200 g. The supernatant containing the whey fraction was diluted with 2 volumes of distilled water and one volume of a 46 concentrated protein sample buffer. The pellet containing the casein fraction was re-suspended in an equivalent of 3 volumes (of starting volume) of distilled water and then one volume of a 46