Processes for the production of a product by the enzymatic treatment of a soluble or particulate substrate with a particulate, immobilized enzyme, by treating a process liquor containing the substrate in a bioreactor to produce a slurry of effluent immobilized enzyme and the product in an effluent liquor. The slurry is subject to a non-immobilized enzyme damaging shear inducing effective separation process to provide effluent immobilized enzyme, and effluent liquor containing the product; and reusing the effluent immobilized enzyme in the enzymatic treatment. The process provides for the reclamation and reuse of the immobilized enzyme even when a further particulate solid is present in the effluent/product stream.