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A membrane‐based extraction process is described for the fractionation of citrus oils to produce an oil stream enriched in oxygenated components. The process relies on the high selectivity of cyclodextrins (CDs) to preferentially bind the desirable oxygenates. In the process, low‐temperature citrus oil flows on one side of a nonporous membrane, and an aqueous CD solution flows on the other side of the membrane. Oxygenates diffuse through the water‐swollen hydrophilic membrane and preferentially partition into the aqueous CD solution. The aqueous CD solution is then heated and circulated past a second membrane, where the CD/oxygenate complex dissociates and the liberated oxygenates diffuse into a citrus oil solution. Disassociated CD is recycled to the first membrane. Data are presented on the effect of temperature and CD type on the partitioning of oxygenates from orange oil into aqueous CD solutions. Operation of a pilot‐scale test loop that capitalizes on the high selectivity of CDs and the temperature dependence of the CD binding is described for the production of oxygenate‐enriched orange oil.

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Many mammalian cells grown in culture excrete ammonia, which, when it accumulates, limits cell growth and reduces product synthesis. Common tactics for minimizing the effects of ammonia accumulation are uneconomical, requiring large quantities of media and incurring high capital costs. Solution-diffusion membranes were investigated for ammonia removal, and a supported-gas membrane was identified that could be used to remove ammonia rapidly to well below inhibitory levels. Medium treated using this membrane was reused to culture baby-hamster kidney cells, resulting in a cell growth rate that was essentially the same as that for cells grown in fresh medium.