Electrophoretic Mobility of Milk Fat Globules. II. Effect of Diluent on Mobility of Fat Globules and Fat Globule Membrane

Microelectrophoretic mobility determinations on large numbers of individual milk fat globules suspended in distilled water demonstrated a wide variation in mobility between globules. The average mobility and variation in mobility decreased markedly when the suspending medimn was a centrifugate prepared by means of superspeed eentrifugation of milk. The variability is shown to be independent of milk fat globule size or age of the electrophoretic suspension. Mobility studies on washed cream showed an increase in mobility and an increased variation of mobility as the number of washings increased. Also, during washing of the cream, the distribution tended to broaden as the washing increased. Variation in electrophoretie mobility when either distilled water or eentrifugate was used as the suspending media tended toward a norreally distributed population. Mobility studies using the Tyndall phenomenon on fat globule membrane particles from buttermilk and butter serum fractions indicated these to be different.