期刊
BIOCATALYSIS AND BIOTRANSFORMATION
卷 30, 期 2, 页码 209-216出版社
INFORMA HEALTHCARE
DOI: 10.3109/10242422.2012.661725
关键词
bio-based surfactant; bioreactor; enzyme; lipase; saccharide-fatty acid esters
资金
- US Department of Agriculture [2006 - 35504-17262]
Saccharide-fatty acid esters - biodegradable, biocompatible and non-ionic bio-based surfactants derived from inexpensive renewable agricultural sources, utilized in foods, cosmetics and pharmaceuticals, have been synthesized under solvent-free conditions using a closed-loop system operated under continuous recirculation consisting of a reservoir, a peristaltic pump and a packed-bed bioreactor containing immobilized Rhizomucor miehei lipase (RML). Metastable suspensions of saccharide crystals were formed through continuous stirring in the reservoir with an in-line filter of 180 mu m normal size preventing larger crystals from clogging the tubing. The initial reaction medium consisted of oleic acid/fructose-oleic acid esters 95/5 w/w, with saccharide added periodically to the reservoir to replace consumed acyl acceptor substrate. The liquid-phase water concentration was retained at a previously determined optimal value of similar to 0.4 wt % through free evaporation of the co-product, water, in the reservoir during the initial phase of the reaction, and N-2( g) bubbling and vacuum pressure after 40 h of reaction. After 200 h, the reaction mixture contained 84 wt % ester, of which 90% of the ester consisted of monoester. Equivalently, the productivity was 0.195 mmol(Ester) h(-1) g(RML) (-1). The resultant technical grade product can potentially be used directly, without further purification. A mathematical model based on mass balances and a zeroth-order kinetic model was successfully developed to predict the concentration of substrates (oleic acid and saccharide) in the reservoir during the time course of reaction.
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