Hypothesis: Natural saponin glycyrrhizic acid (GA) and GA nanofibrils (GNFs) are effective foaming agents for formulation of aqueous food-grade foams. Through the synergistic combination of soft semiflexible GNFs with rigid nanofiller cellulose nanocrystals (CNCs), it should be possible to create advanced composite foams with a more complex structure and diverse properties including high stability and stimuli responsiveness. Experiments: Foams containing mixtures of GNFs and CNCs were prepared, and their formation and stability were investigated. A range of microscopy techniques and small deformation oscillatory shear were adopted to examine the microstructure and viscoelasticity of foams, and a stabilization mechanism for highly stable foams was then established. Further, the temperature-responsive destabilization of foams was evaluated. Findings: CNCs are homogeneously distributed in the architecture and mechanically reinforce the GNF fibrillar network, leading to a highly viscoelastic composite network in the continuous phase of foams, which is the key factor responsible for their high stability. Such ultra-stable gel foams display tunablethermo-responsive behavior and a rapid on-demand destabilization upon heating by inducing a phase transition of the bulk composite network. Our work opens up new scenarios on the use of a novel combination of all-natural, sustainable nanoscale building blocks to develop aqueous "superfoams" which are highly stable, stimulable and processable. (C) 2020 Elsevier Inc. All rights reserved.