Enzyme cleaning of heat exchangers

  • Friis, Alan (Project Manager)

    Project Details


    Fouling of heating surfaces is one of the most significant problems in processing of milk. The deposit of a fouling layer results in a significant decrease in heat transfer capacity.
    The present project deals with substitutsion of the use of alkaline cleaning agents, which are damaging to the enviroment and not highly effective for cleaning of milk deposits
    For cleaning of dairy equipment CIPzyme has been developed by Novo Nordisk A/S. CIPzyme contain protease and lipase activities in order to produce surfactants (soaps) in situ from the fat and emulsifiers and foaming agents from the proteins.
    The investigations shows that CIPzyme reduces the surface tension of the cleaning solution as a result of the substances formed by the enzyme from the milk deposit layers on the stainless steel. The degree of the reduction is dependent on the substrate availability rather than the concentration of CIPzyme. The hydrolytic effect depends mainly on the fat content of the milk but also of the concentration of the enzyme. The cleaning experiments in the model system proved that CIPzyme could clean stainless steel surfaces fouled by milk due to both enzymatic degradation of the soil and due to the surfactants formed in situ during the cleaning. The cleaning efficiency was related to the hydrolytic effect.
    Pilot plant scale experimets showed that the CIPZyme familly of cleaning enzymes works for cleaning of a plate heat exchanger fouled by milk deposits. However, the efficiency did not prove to be sufficient at this stage. Further work needs to be put into types of milk deposits and optimisation of the enzyme application before industrial application is realistic.
    Effective start/end date01/01/199830/06/1999