Phase inversion regulable bigels co-stabilized by Chlorella pyrenoidosa protein and beeswax: In-vitro digestion and food 3D printing

Algal proteins are an emerging source of functional foods. Herein, Chlorella pyrenoidosa protein (CPP)/xanthan gum-based hydrogels (HG) and beeswax-gelled oleogels (OG) are adopted to fabricate bigels. The phase inversion of bigels can be regulated by the ratio of OG and HG: As the OG increased, bigels turn from OG-in-HG (OG/HG) to a semicontinuous state and then HG-in-OG (HG/OG). In OG/HG bigels (OG ≤ 50 %), hydrophilic CPP acts as the emulsifier at the interface of OG and HG, while beeswax emulsifies the system in HG/OG bigels (OG = 80 %). A semicontinuous bigel appears during the transition between HG/OG and OG/HG. The increase of OG can enhance the viscoelasticity, hardness, adhesiveness, chewiness, and thermal stability. OG/HG bigels exhibit stronger thixotropic recovery and oil-holding capacity than HG/OG bigels. In the in-vitro digestion and food 3D printing, the high specific surface area and the highest thixotropic recovery caused by the emulsion structure of the OG/HG bigel (OG = 50 %) are conducive to the release of free fatty acids and molding of 3D-printed objects, respectively. This study provides a new approach to structure the gelled water-oil system with CPP and helps to develop edible algal proteins-based multiphase systems in food engineering or pharmacy.