Laboratory studies on cleaning milk heaters with enzymatic cleaning solutions

At the cleaning of pasteurized milk processing plants in Germany the annual inorganic (not biodegradable) cleaning chemicals, which have to be dispose d with the waste effluents, amount to more than 1.000 tons. Experiments wer e carried out to replace the sodium hydroxide, which is mainly used in the alkaline cleaning step in a concentration range between 0.5 and 3.0 %, by a n enzymatic treatment. In a laboratory scale CIP-plant cleaning trials were performed using test elements which previously had been soiled with a stan dardized deposit similar to that arising in heat exchangers during the past eurization process of fluid milk. Several enzyme containing preparations of two German manufacturers of cleaning agents for the food industry were tes ted under defined process conditions (temperature, pH, concentration) and w ere compared to the efficiency of a 0.5 % sodium hydroxide solution. Two pr eparations containing the enzymes 'Savinase' (manufactured by Novo Nordisk) and 'Properase 1.600 L' (manufactured by Genencor International) turned ou t as particularly efficient. The use of these preparations resulted in meta llic clean surfaces. With a Savinase containing product a cleaning trial at a 45.000 I/h milk heater was performed in a dairy, it led to a perfect cle aning result. Questions in connection with the commercial introduction of t he enzymatic cleaning procedure are actually discussed within the dairy sec tor.