Tuning Nanostructure of Gels: From Structural and Functional Controls to Food Applications

Abstract

Various gels are integral for the food industry, providing unique textural and mechanical properties essential for the quality and functions of products. These properties are fundamentally governed by the gels' nanostructural organization. This review investigates the mechanisms of nanostructure formation in food gels, the methods for their characterization and control, and how precise tuning of these nanostructures enables targeted food applications. We examine the role of various building blocks, including biopolymers, lipids, and particles, and the gelation mechanisms leading to specific nanostructures. Advanced techniques (e.g., microscopy, scattering, spectroscopy, and rheology) are discussed for their insights into nano-/microstructures. Strategies for tuning nanostructures through chemical composition adjustments (e.g., concentration, pH, ionic strength) and physical processing controls (e.g., temperature, shear, ultrasound) are presented. Incorporating nanostructures like nanoparticles and nanofibers to enhance gel properties is also explored. The review links these nanostructures to key functional properties, including mechanical strength, water-holding capacity, optical characteristics, and bioactive delivery. By manipulating nanostructures, products can achieve tailored textures, improved stability, and controlled nutrient release. Applications enabled by nanostructure tuning include tailored sensory experiences, fat reduction, innovative food structures, and smart packaging solutions. Although significant progress has been made, precise structural control and a comprehensive understanding of complex nanoscale interactions in food gels remain challenging. This review underscores the importance of nanostructure tuning in food gels, highlighting its potential to drive future research that unlocks innovative, functional food products.

Keywords: 3D food printing; biopolymers; controlled release; food structure design; functional foods; gelation; nanostructure; rheology; texture.

Figure 2

Summary diagram of the gelation mechanism, including: Temperature-set gelation: temperature-induced gelatin gels; Ion-induced gelation: Ca²⁺-induced alginate gels forming egg-box structure; Phase separation: phase separation and gelation in konjac glucomannan and gelatin system (reproduced from [70] with permission from Elsevier); Crystallization: temperature-induced starch retrogradation to form gels; Chemical cross-linking: polymers chains crosslinked by cross-linking agent; Enzymatic cross-linking: polymers chains crosslinked by enzyme; Self-assembly and supramolecular gelation: peptides or low-molecular-weight gelators form supramolecular architectures through molecular interactions.

Figure 3

(A) SEM image of gelatin/chitosan/3-phenylacetic acid nanofiber film (adapted from [76] with permission from Elsevier). (B) Micrographs of whey protein isolate (WPI) and soy protein isolate (SPI) gels obtained through confocal laser scanning microscopy (adapted from [77]). High-resolution STED microscopy images of acidified fresh skimmed-milk gels (ASMG) with and without pectin: (C) The control gel without pectin; (D) Gels with high-methoxy pectin (HMP) (AMD 783); (E) Gels with low-methoxy pectin (LMP) (PSY 200) (adapted from [78] with permission from Elsevier).

Figure 4

Mesoscale rheology of iota–carrageenan (IC) gels at different strain rates using optical tweezers (OT). The measured force response (symbols) as a function of stage movement at different speeds. The dashed line represents the stage displacement (adapted from [100] with permission from Elsevier).

Figure 6

(A) Visual appearance of starch emulsion-filled gels formed by 0–90 °C gelation. Red arrows show the edges of the emulsion-filled gels under loading. (B) Storage (G’) and loss (G”) modulus, and (C) tan δ as a function of frequency for starch emulsion-filled gels formed by different gelation temperatures (55–90 °C) (adapted from [134] with permission from Elsevier). (D) The appearance of cellulose hydrogels obtained from different ultrasonic durations (left) and the reversible property of hydrogels (right). (E) The morphology of nanocellulose particles from different hydrogels characterized by atomic force microscopy (AFM) (adapted from [149] with permission from Elsevier). The scale is 1 μm.

Figure 7

(A) Schematic diagram of emulsion and emulsion gels prepared by soy protein isolate (SPI)-pectin complex nanoparticles and glycyrrhizic acid (GA) nanofibrils (adapted with permission from [183]. Copyright 2020 American Chemical Society). (B) Mechanism diagram of whey protein isolate (WPI) composite gel strengthened by whey protein isolate fibrils (WPIF) with different scales at different pH (pH 2.0 and pH 7.0) (adapted from [189] with permission from Elsevier).

Figure 1

Overview of building steps and structures of food gels, including hydrogels, aerogels, oleogels, and bigels, and their application fields. Created in BioRender. group, n. (2025) https://BioRender.com/orxhurf (accessed on 10 July 2025).

Figure 5

(A) Visual appearance, WHC, and gel strength of cellulose nanocrystals-whey protein isolate composite gels with different concentrations of Ca²⁺ (adapted from [68] with permission from Elsevier). Different lowercase letters (a–d) indicate significant differences among treatments (p < 0.05). (B) Chemical structure of the ionic complementary sequence, naphthoxyacetic acid-FEFK peptide, and schematic representation of the self-assembling behavior of the designed peptide sequence depending on the pH of the system (adapted with permission from [110]. Copyright 2020 American Chemical Society). (C) Schematic description of a low-molecular-weight gel assembling to form fibrous structures that entangle to form a network: Single-component and two-component systems (adapted with permission from [111]. Copyright 2022 American Chemical Society). (D) Different conventional bigels obtained by varying organogel/hydrogel ratio (adapted from [112] with permission from Elsevier).

Figure 8

Schematic diagram of various applications of gels in food areas.