Development, characterization and tailoring of edible biphasic gels for applications in food

Bigels are semi-solid biphasic gels that are composed of a structured oil phase, also known as an oleogel, and a hydrogel combined at a high shear rate. The combination of these two gels provides unique mechanical properties, compatibility with both lipophilic and hydrophilic moieties and improved physical stability over other semi-solid formulations. Recently, bigel research has extended toward food applications such as saturated fat replacement, encapsulation of sensitive bioactive agents and texture modification. The physicochemical properties and behavior of bigels must be well understood so targeted formulations can be manipulated and tailored for specific applications. In this research project, a gelatin hydrogel is combined with wax-based oleogels to produce edible bigels for potential application as novel food ingredients. The effects of changing the oleogel-to-hydrogel ratio, hydrogelator concentration, addition of mono-diglycerides, a common emulsifier, and chemically crosslinking the hydrogel phase on the mechanical, thermal and microstructural properties were determined. Bigel formulations that contained higher proportions of oleogel (40% and 50%) and 7% hydrogelator exhibited optimal mechanical strength (G’). The addition of mono-diglycerides significantly altered the hardness of the bigel but increased its physical stability. Mono-diglycerides were found to serve as both an emulsifier and fat crystal modifier, making it an additional way to tailor and improve bigels for specific applications. Chemically crosslinking the hydrogel reduced the overall molecular mobility of the bigel matrix while also providing unique thermal properties that may result in enhanced long-term stability. The stability and capability to tailor the properties of this bigel system make it promising candidate for application in fat mimetics, as well as other potential food applications.