The production of high-value dairy proteins such as lactoferrin and lactoperoxidase normally requires extensive pre-treatments of milk to remove fat and caseins by centrifugation, precipitation, Ca 2+ chelation and/or filtration. Similarly, fat and caseins are normally removed prior to capture of recombinant proteins from the milk of transgenic animals. Such pre-treatments can result in significant loss of protein yield and/or activity. In this paper we demonstrate that it is possible to pass significant quantities of raw, untreated milk through a 5 cm high chromatography column packed with SP Sepharose Big Beads™ (GE Healthcare, Uppsala, Sweden) without exceeding the maximum allowable backpressure, provided that the processing temperature is kept nominally around milking temperature (35 to 37 o C).Results show that more than 100 column volumes of raw milk could be loaded at 300 cm/hr before breakthrough of lactoperoxidase occurred. The dynamic capacity for adsorbing lactoferrin and lactoperoxidase simultaneously under these conditions was approximately 48.6 mg/mL of resin. Minor leakage (4.6% of the feed concentration) of lactoferrin occurred throughout the loading process but major breakthrough occurred only after approximately 100 column volumes was loaded.

Batch extraction of proteins directly from raw, whole milk is described with a focus on design considerations for on-farm implementation. A demonstration of single-stage stirred tank extraction of bovine lactoferrin onto cation exchangers shows that processing can be achieved, with no pre-treatment of raw milk, within the timeframe required to milk an On-farm extraction of proteins shows promise for both the production of minor, high-value proteins from conventional milk and for production of recombinant proteins from the milk of transgenic animals. The main advantage of the stirred tank process is that protein extraction is rapid and is achieved in a single step without the need for pre-treatment of milk. The process is not limited to ion exchange but could be implemented using other chromatographic techniques, such as affinity or reverse-phase chromatography.2