Production of specific-structured lipids by enzymatic interesterification in a pilot continuous enzyme bed reactor

Production of specific-structured lipids (interesterified lipids with a spe cific structure) by enzymatic interesterification was carried out in a cont inuous enzyme bed pilot scale reactor. Commercial immobilized lipase (Lipoz yme IM) was used and investigations of acyl migration, pressure drop, water dependence, production efficiency, and other basic features of the process were performed. The extent of acyl migration (defined as a side reaction) occurring in the present enzyme bed reactor was compared to that in a pilot batch reactor. The continuous enzyme bed reactor was better than the batch reactor in minimizing acyl migration. Generally the former produced about one-fourth the acyl migration produced by the lat ter at a similar extent o f incorporation. Pressure drop and production efficiency were evaluated in order to obtain a suitable yield in one reaction step. High incorporation w as favored by high substrate ratios between acyl donors and oils, requiring long reaction times on the enzyme bed. Under these conditions, the pressur e drop of the reactor was modeled statistically and theoretically. Residenc e time, water content, and effects of mass transfers were also investigated . Incorporation of medium-chain fatty acids increased with increased reside nce time. Approximately 40% of lipase activity was lost after a 4-wk run. E xternal mass transfer was not a major problem in the linear flow range, but internal mass transfer did impose some transfer limitations.