Reduction of CO2 emission and energy use during cleaning of milk deposits using ultra-smooth stainless tubing

Abstract

• Ultra-smooth MAF finishing modifies milk deposit detachment during water-only CIP. • Surface roughness benefits depend strongly on milk drying temperature. • Smoother surfaces reduced cleaning energy and CO₂ emissions for milk deposits formed at 45°C. • Step-response modeling predicts deposit detachment, aiding CIP process optimization. • MAF-treated pipes improve hygiene and sustainability in dairy CIP operations. The efficiency and sustainability of Clean-in-Place (CIP) operations in dairy processing are strongly influenced by pipe surface characteristics and the thermal history of milk deposits. This study investigated the effects of stainless-steel pipe inner surface roughness and milk drying temperature on deposit formation, deposit removal, energy consumption, and resulting energy consumption CO₂ emissions. Two pipe types were compared: a conventional sanitary pipe ( Ra : 0.37 ± 0.07 μm) and a magnetic-abrasive finishing (MAF) pipe ( Ra : 0.01 ± 0.001 μm). Milk deposits were formed at 45°C and 55°C, and water-based cleaning trials were conducted, with deposit removal quantified. The ultra-smooth MAF pipes demonstrated markedly lower deposit adhesion and higher deposit removal kinetics with 38–50% less energy at 45°C compared to conventional pipes. These energy savings correspond to a proportional reduction in CO₂ emissions. In contrast, deposits formed at 55°C were strongly resistant to removal, and the advantages of surface smoothing largely diminished, indicating that deposit cohesion dominated over surface roughness effects under thermally strengthened fouling conditions. The findings highlight the potential of ultra-smooth surfaces to enhance cleaning efficiency, reduce energy consumption, and improve the environmental sustainability of dairy processing.