Emulsifying properties of food by-products: Valorizing apple pomace and oat bran

The potential emulsifying properties of two food byproducts, apple pomace and oat bran, were investigated to assess if their insoluble and soluble contents can stabilize oil in water emulsions. If so, this would mean that such raw, unpurified and complex materials could be used whole, with no additional processing and/or solvents added to separate and purify the desired fractions. If the two byproducts only need to be dried and micronized, the environmental impact would be considerably reduced. Rapeseed, jojoba and myritol oils were used to assess feasibility for both food and cosmetic applications. Dynamic rheological measurements, droplet size distribution, backscattered light, light and confocal microscopy showed that apple powder has better emulsifying potential, especially in myritol and rapeseed oil. The action of the insoluble fibers maintained the stability of the emulsions through Pickering mechanism and/or network formation in the continuous phase, probably favored by stabilization of proteins and pectins in the soluble fraction. Such raw materials can thus be a renewable source of stabilizing agents with useful functional properties such as gel behavior and stability against coalescence.