Mechanistic insights on surface adsorption of rice-based biomolecules on stainless steel 316L and its effects on corrosion and metal migration

Austenitic stainless steel (AISI 316L) is the dominant material in food processing equipment due to high corrosion resistance and mechanical durability. The shift from animal- to plant-based food processing introduces new challenges for material performance, as plant-derived biomolecules may interact differently with food-contact surfaces than animal proteins. These interactions can modify interfacial properties, with consequences for fouling, corrosion, and metal migration. Despite its importance, such effects remain scarcely studied, with only a few reports on e.g. whey and casein proteins. Knowledge on rice-derived biomolecules is particularly limited, even though rice proteins and starches are increasingly relevant in gluten-free and plant-based systems. This study examines the adsorption kinetics and interfacial properties of rice protein concentrates (RPC) and rice starch (RS) dissolved in artificial tap water (ATW) onto 316L stainless steel. In situ quartz crystal microbalance with dissipation monitoring (QCM-D) was employed to quantify adsorption dynamics, complemented by atomic force microscopy (AFM) and carbohydrate-specific opto-tracing (Carbotrace 680) to detect, and visualize adsorption patterns. Atomic absorption spectroscopy (AAS) was used to determine metal migration and evaluated with respect to European Union specific release limits (SRLs) for food-contact materials. Electrochemical measurements including open circuit potential (OCP), potentiodynamic polarization (PDP), and cyclic potentiodynamic polarization (CPDP) were employed to assess the effects of adsorption on the corrosion behavior. By demonstrating how rice-derived biomolecules interact with stainless steel and influence corrosion and metal migration, this study addresses a critical knowledge gap in the literature. The insights advance fundamental understanding of food biomolecule–metal interactions and support the design of more durable, compliant, and safe food-contact materials. • QCM-D revealed rapid adsorption of rice protein (RPC) and starch (RS) onto 316L stainless steel. • AFM and opto-tracing marker visualized uniform layers with occasional aggregates. • RPC and RS slightly increased Fe and Mn release, remaining below EU limits. • Adsorbed layers altered the initial OCP but did not affect the long-term corrosion resistance. • Insights support durable, safe, and hygienic design for plant-based food processing.