The present invention relates to a process for removing the fouling deposited in a milk processor unit after a thermal processing of milk or a food product including milk at a T between 80°C and 150°C for at least 4 hours, including said fouling proteins, lactose, minerals and products formed therefrom, comprising the step of applying a cleaning solution on said fouling deposited in the milk processor unit. The present invention further relates to a cleaning solution suitable to be used in the process according to the present invention. Fig.1