An example system for purifying a supply stream including lactose includes a clarification system configured to separate insoluble impurities from the stream to produce a clarified stream. The system includes an adsorption system fluidically coupled to the clarification system. The adsorption system includes an adsorbent resin configured to purify the clarified stream. An example technique for purifying a supply stream including lactose includes separating insoluble impurities from the supply stream to produce a clarified stream and passing the clarified stream over an adsorbent resin to produce a decolorized stream.