Magnetite was set in a channel as an open system and was placed there by application of a magnetic field to form an assembled-magnetite membrane. A starch-granules-dispersed solution flowed from the top of the channel to allow recovery of starch granules by the assembled-magnetite membrane by size effect. The size of starch granules dispersed was ranged from 1 to 60 mu m. The magnetite density in the membrane was strongly related to the recovery efficiency. To alter the density of the assembled-magnetite membrane, the amount of magnetite in the channel ranged from 0.05 to 0.5 g. With increasing membrane density, the recovery efficiency increased. After recovery by the membrane, the flown starch granules through the membrane were observed by optical microscopy, and were found to be less than 10 mu m in diameter. The proposed assembled-magnetite membrane has the potential for recovery of starch granules and other food particles used for cooking based on molecular gastronomy. (C) 2013 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.