Glycyrrhizic acid nanofibrils as potent ice recrystallization inhibitors: mechanism and application in ice cream.

Ice recrystallization compromises both frozen food quality and cryopreservation outcomes. Existing solutions face challenges such as high costs, low activity, and poor biocompatibility. This study demonstrates that glycyrrhizic acid (GA), a natural triterpenoid saponin, self-assembles into nanofibrils (GANFs) that exhibit potent ice recrystallization inhibition (IRI) activity. The nanofibrillar structure is essential for this activity, as dissociation into monomers at pH 7.0 or surfactant-induced disruption abolishes IRI activity. Similarly, lateral aggregation of GANFs at pH 2.0 impairs activity by reducing the population of freely diffusing fibrils. The IRI mechanism involves the confinement of water molecules within hydration layers, reducing water mobility, rather than direct binding to ice surfaces. The IRI activity of GANFs is modulated by ionic strength and pH. Gelation and structural disruption of GANFs at elevated NaCl concentrations progressively diminish IRI activity, whereas GANFs retain observable IRI activity in high-concentration sucrose solutions, where the dilution effect alone cannot account for the loss of activity. When incorporated into ice cream, GANFs reduce ice crystal size by over 50% during seven days of storage without largely affecting sensory or physicochemical properties. These findings highlight GANFs as a promising natural material for enhancing frozen food quality, offering a novel approach to controlling ice recrystallization through water confinement, while addressing the limitations of current IRI materials.