AgResearch Limited in conjunction with industry partner, Keratec Limited, have been developing a commercially viable protein extraction process. This extraction process results in the generation of several aqueous protein-rich streams of varying composition, functionality and commercial value. This work has focused on the purification and concentration of a water soluble protein stream and involved undertaking laboratory based experiments and technology transfer to full scale.
Previous experience has shown that the water soluble protein stream is sensitive to harsh processing conditions, such as high/low pH and temperature. This results in a darkening of the colour of the final protein solution and the formation of a cloudy precipitate over time. Laboratory scale trials indentified a range of optimal processing conditions (pH, temperature, pressure, time etc). Pilot scale trials focused on developing commercially viable production processes based on the guideline processing condition identified in the laboratory. Full scale trials were used to confirm the conditions established at pilot scale were achievable and commercially viable.
This work has identified that membrane filtration, using ultra-filtration (UF) membranes, is an effective method to purify and concentrate the water soluble protein stream as it separates salts from the larger protein molecules. Protein yield was optimised by controlling the processing conditions to minimise the leakage through the membrane. Maximum yield was achieved using a two-stage process, combining evaporation and UF; although careful control of the processing conditions (temperature and time) was required avoid adversely affecting the quality of the final product.