Date of this Version
Usable life of cleaning solutions in a model heat processing unit was studied by evaluation of the nature and quantity of residue remaining on the surface of the equipment after cleaning. Lipoidal residue was recovered from equipment surfaces by ether rinsing. A surface displacement technique was used to quantify the lipoidal material, which was characterized by gas-liquid chromatographic analyses of triglycerides and fatty acid methyl esters. Effects of factors, such as water hardness, rinse water temperature, cleaning solution additives and acid versus alkaline cleaners also were investigated in relation to overall cleaning efficiency. After evaluating limits of reuse of cleaning solutions, used solutions were regenerated by sorption of lipoidal residue on Celite, resulting in restored cleaning effectiveness. When spent-cleaning solutions were circulated in previously cleaned equipment, there was redeposition of lipoidal material onto the equipment surfaces.