Emulsion-templated walnut oil oleogels stabilized by Maillard reaction-treated common bean protein as a solid fat substitute in bakery products

Oleogels are structured systems for creating three-dimensional networks from liquid oils, used as an alternative to solid fats to reduce trans and saturated fat contents. The approach of obtaining oleogels via concentrated emulsions and high internal phase emulsions (HIPEs) allows for long-term stability and low surfactant requirements. The Maillard reaction between proteins and polysaccharides is considered a reliable and economical modification method, providing steric stabilization against droplet coalescence. It was hypothesized that Maillard-modified bean proteins could contribute to the physical and oxidative stability of walnut oil-based oleogels through improved solubility and steric hindrance. An emulsion-based walnut oil oleogel system stabilized by Maillard reaction-treated bean protein was developed for the first time. The degree of glycation, emulsion properties, and gelation capacity of the Maillard conjugates were investigated. This was followed by the characterization of the emulsions and oleogels obtained using these conjugates (e.g., via FTIR, GC-MS, oxidative stability assays). The optimized oleogel was used as a margarine substitute in cookie formulations. Results indicated that the Maillard reaction-treated bean protein conjugate (MLC) exhibited high emulsion stability (ESI: 201.52 min) and low gelation concentration (5%). Moreover, the lowest oil loss (21.3%) and high thermal stability were achieved in the 30:70 (v/v) oleogel (OL) formulation. The presence of MLC in the oleogel structure improved the oxidative stability by decreasing the TBARS values from 0.33 to 0.26 mg MDA/g oil and K₂₃₂ values from 0.373 to 0.205 after 40 days of storage at room temperature. In cookie applications, the oleogel-based formulations provided hardness values between 39.5 and 63.9 N, compared to the control (38.2 ± 2.6 N). These findings indicated that MLC-based emulsion-templated oleogels could be used as a healthy solid fat replacement by preserving the high PUFA content of the oil.