Gliadin-based nanoparticles: Fabrication and stability of food-grade colloidal delivery systems

There is great interest in converting gluten, a by-product from wheat starch isolation, into a value added functional food ingredient. The insolubility of monomeric gluten, i.e. gliadin, in water makes these proteins interesting materials to produce nanoparticles using liquid antisolvent precipitation. The effect of different production parameters (such as mixing speed, time, sonication parameters, gliadin concentration) on the properties of gliadin particles formed by liquid antisolvent precipitation was investigated. The produced particles were also hardened using glutaraldehyde (0–0.25%). The stability of the produced gliadin particles was investigated in different pH and salt conditions relevant for food processing and upon short term temperature treatments and isothermal long-term storage. Gliadin nanoparticles (diameter < 200 nm) could be produced, however, they had poor stability in different conditions relevant to food processing: they redissolved below pH 4.0 and flocculated near their isoelectric point (pH ≈ 6.5), at elevated salt levels, and after heat treatment (T > 40 °C for 30 min). A slight improvement in particle stability was obtained by chemical hardening (0.25% glutaraldehyde). Gliadin nanoparticles may be useful in the development of delivery systems to encapsulate, protect, target and release active ingredients during food processing or after ingestion. However, additional strategies to stabilize the particles should be explored.