Quantitation of Proteinaceous Soil Removal from Clean-in-Place Systems

The protein of milk residue can be quanti tated to evaluate a cleaning process by monitoring the accumulation of protein in a test-wash solution. The test for protein is based on precipitat ion of hard water cations with or thophosphate and flocculation with a coagulant for rapid sedimentat ion of the protein. The sediment is collected on filter paper and stained with xylene brilliant cyanin G. Color reaction on the filter paper is proport ional to protein content of the original test solution and is estimated visually. For more precise quanti tat ion, the stain is released into a solution for optical measurements. The lower limit of sensitivity is approximately 34 ng of protein per ml in the original caustic test wash. Quanti ty of added protein to a caustic test wash and optical density of the final test dye solution showed a correlation coefficient of .99. The method developed in this work should be useful in studying clean-in-place regimen to evaluate commercial practices and fundamentals of the processes.