8-4 |
Challenges in downstream bioseparation and purification |
M. CHERYAN, Depts. of Food Science & Human Nutrition and Agricultural Engineering, Univ. of Illinois, Urbana-Champaign, Agricultural Bioprocess Lab., 1302 W. Pennsylvania Ave., Urbana, IL 61801 The separation of bioactive compounds from crude fermentation broths or plant extracts require unit operations that are quite different from traditional chemical separation processes. It is important to maintain the compound's bioactivity while maximizing its purity and yield. However, these three parameters are often mutually exclusive. One big hurdle is that the compound is usually present in very low concentrations of a few hundred ppm to 10% of the broth. Another is that the impurities could have physicochemical properties that are similar to the target compound of interest, making conventional separations difficult. The primary downstream operation is the removal of insolubles (e.g., by sedimentation, filtration, centrifugation, membranes), followed by isolation of the compound (e.g., precipitation, extraction, adsorption, membranes) and final purification (e.g., crystallization, chromatography). The use of organic solvents for extraction and purification of nutraceuticals is increasing, which creates its own set of challenges. For example, many of the membranes used today were designed for aqueous systems and not for use with organic solvents. Case studies of bioseparations in the production of organic acids from fermentation broths and for carotenoids from plant materials will be presented.
Session 8, Challenges and outlook of bioprocess engineering in food
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