beta-Fructofuranosidase was immobilized by alginate gel at high efficiency (92 %). The extre me long-term continuous reaction (half-life, 275 days) was achieved by the immobilized enzyme using sucrose at high concentration (500 mg ml(-1)) to produce fructo-olicosaccharides, such as 1-kestose (Fru beta 2-->1Fru beta 2-->1 alpha Clc) and nystose (Fru beta 2-->1Fru beta 2-->1Fru beta 2-->1 alpha Clc).