Adsorbed proteins are among the most difficult food soils to remove from food contact surfaces.  In particular, heat-denatured proteins (such as those found in dairy industry applications) adhere tightly to surfaces and require strong alkaline cleaners for removal.  It is important that cleaning methods are capable of removing both visible and non-visible protein soils.  Nutrients for bacterial growth must be removed as well as biofilms that may have built up on the food contact surface.  Proteins are water-insoluble, slightly soluble in acidic solutions and soluble in alkaline solutions, which limits the type of cleaner that can be used to remove protein from the surface.  Generally speaking, highly alkaline cleaners with peptizing and wetting agents are most effective in protein removal on food contact surfaces.  Cleaning temperature is also a concern for effective protein removal.  As temperature increases, the activity of the cleaning compound increases, making soil removal easier.  However, at higher temperatures (> 55 °C) proteins denature and cleaning efficacy is reduced.