Pickering emulsions with controllable rheological properties stabilized by oat globulin at different pH levels

Plant-based proteins have garnered increased attention in recent years due to their unique interfacial properties and biocompatibility. However, their low solubility under neutral pH conditions has always limited their applications. In this paper, oat globulin (OG) (0.01 wt% - 0.05 wt%) could solely stabilize Pickering emulsions with controllable rheological properties at different pH without any modifications. Low viscosity Pickering emulsions (V oil :V water = 1:1) with stability exceeding six months were formed at pH= 2 (221 Pa s) and 12 (109 Pa s), owing to the formation of small OG aggregates (100 nm) with high interfacial activity. Conversely, at pH= 5–10, Pickering emulsions with high viscosity were obtained, where larger-size OG particles aggregated at the oil-water interface. Therefore, the stability, droplet size, and viscosity of the Pickering emulsions stabilized by OG particles could be regulated by pH variation. The strategy harnesses the OG aggregation state at diverse pH levels to engineer emulsions with distinct properties, avoiding the need for chemical grafting modifications, heat, or high-intensity ultrasound treatments, which holds promise for potential applications in functional materials.