Fouling behaviour of milk and whey protein isolate solution on doped diamond-like carbon modified surfaces

Doped diamond-like carbon (DLC) coated stainless steel surfaces were studied for their fouling behaviour with milk and whey protein isolate (WPI) solution at both laboratory and pilot-scale. Stainless steel (316 SS 2B) surfaces were modified with three different doped DLC coatings (DLC-1, DLC-2 and DLC-3) using plasma assisted chemical vapour deposition. At the laboratory-scale, the DLC-1 coated surface showed a statistically significant reduction in the mass of milk fouling deposits. However, at the pilot-scale, none of the modified surfaces offered significant benefit in fouling mitigation over the control stainless steel surface. Subsequently, in the laboratory-scale trials with a whey protein isolate (WPI) solution, the mass of fouling deposits for all doped DLC modified surfaces were about 35–40% lower in comparison to their controls when fouled for 120 min. However, these benefits were reduced to less than 15% with longer fouling duration. Thus, the results obtained in this study found no commercial benefit of modified surfaces in fouling mitigation when fouled for longer times with skim milk, whole milk or WPI solution.

► Doped DLC modified surfaces fouled similar to stainless steel when studied with milk.
► Fouling deposit mass was independent of the surface energy.
► The modified surfaces showed no benefit in easy removal of deposit mass.
► Significant benefit in fouling mitigation was found with WPI solution at lower deposit mass.