There was a clear distinction between the different
layers. Patton reported that binding to concanavalin A,
retention by anion-exchange cellulose and resistance
to precipitation by heating was a useful system for
isolation of Prosaposin in milk. Kunz and Lonnerdal
(1989), concluded that separation of human milk into
fat, whey and casein by centrifugation without prior
pH adjustment does not yield distinct layers.