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 .