Morel Mushrooms Reshape Chicken Broth Particles for Better Emulsion Stability

Tibetan chicken broth, long prized on the high plateaus of China as a nourishing tonic, is at its heart a colloid chemistry problem. During hours of slow stewing, proteins, lipids, and carbohydrates leach from the meat matrix into the liquid and spontaneously co-assemble into supramolecular structures known as micro/nano-particles, or MNPs. These particles, held together by hydrophobic interactions, hydrogen bonding, and electrostatic forces, fundamentally determine how stable the broth’s emulsion is, how it feels in the mouth, and how its texture develops over time. A new study published in Food Chemistry: X now reports that adding dried morel mushrooms, Morchella esculenta, to the stewing pot systematically reshapes these particles, producing smaller, more uniformly charged colloids with measurably improved emulsifying activity and stability.

The research team, led by Kai Dong and Qun Huang, designed a controlled comparison using female Tibetan chickens purchased from a farm in Sichuan, China. Thawed birds were divided into equal halves and assigned to two groups: a control group stewed without morel, and a treatment group stewed with dried morel at 4.0 percent of the meat weight. Both groups were stewed for three hours, with 100 milliliter broth samples withdrawn at 15 minutes, 30 minutes, 1 hour, 2 hours, and 3 hours; evaporated water was replenished after each sampling to keep volumes constant. To isolate the MNPs, the broth was filtered through double-layer cheesecloth and passed through ultrafiltration tubes with a 100 kilodalton molecular weight cut-off, followed by centrifugation at 5000 times gravity for 30 minutes. The retentate collected in the inner tube served as the MNP solution for all subsequent analyses.

The first striking result concerned nutrient release. Across the entire three-hour stewing process, both the soluble protein and total sugar contents of the MNPs rose significantly and continuously over time in both groups, reflecting sustained thermal degradation of collagen into gelatin and the denaturation of myofibrillar proteins. However, at every evaluated time point, the morel group showed significantly higher protein and total sugar contents than the control, a difference the authors attribute to the fungus’s intrinsic richness in functional proteins and polysaccharides, which are progressively released as heat disrupts the fungal cell walls. Protein solubility, a critical prerequisite for interfacial activity, also climbed steadily in both groups, and the morel-supplemented broth reached a maximum solubility of approximately 98.71 percent at the three-hour mark. The researchers suggest that fungal polysaccharides act as hydrophilic protective colloids, attaching to meat protein surfaces and providing steric hindrance that limits heat-induced aggregation.

The colloidal parameters told an equally compelling story. Using dynamic light scattering on a Zetasizer, the team measured particle size, polydispersity index, and zeta potential throughout the stewing period. In both groups, particle size and polydispersity declined progressively while the absolute zeta potential increased, indicating that prolonged heating drives a supramolecular rearrangement of released amphiphilic molecules into a more uniform and stable colloidal system. Morel addition amplified every one of these effects. The treatment group displayed significantly smaller particles and lower polydispersity throughout the process, with the average particle size reduced to 268.57 nanometers by the end of stewing. The polydispersity index fell from roughly 1.0 to below 0.5, a transition the authors describe as a shift from a highly heterogeneous coarse suspension to a relatively homogeneous colloidal dispersion.

The zeta potential results were particularly dramatic. At all time points, the morel group’s absolute zeta potential was significantly higher, and more negative, than the control’s. At the earliest sampling point, just 15 minutes into stewing, the absolute zeta potential of the morel group was already nearly four times that of the control, implying that fungal-derived components rapidly altered the surface properties of the particles. The authors link this strongly negative surface charge to the integration of morel polysaccharides into the interfacial layer; Morchella esculenta polysaccharides are reported to contain uronic acids, including glucuronic and galacturonic acid, with uronic acid contents ranging from 8.6 to 36.91 percent depending on extraction method. A denser accumulation of these negatively charged groups on the particle surface elevates electrostatic repulsion and raises the energy barrier against droplet collision.

Spectroscopic evidence pointed to the molecular mechanisms behind these changes. Fourier transform infrared spectroscopy of the amide I band revealed that as stewing progressed from 15 minutes to 3 hours, both groups showed a progressive decrease in alpha-helix and beta-turn contents alongside increases in beta-sheet and random coil structures, a signature of thermal protein unfolding and subsequent intermolecular rearrangement. The morel group showed significantly lower alpha-helix and higher random coil content at corresponding time points, suggesting enhanced molecular flexibility, which generally allows proteins to unfold, diffuse, and reorient more rapidly at an oil-water interface. Intrinsic fluorescence spectroscopy added a further layer: fluorescence intensity rose with stewing time in both groups as buried hydrophobic fluorophores were exposed, but the morel group showed pronounced quenching throughout, which the authors interpret as evidence of non-covalent interactions between fungal polysaccharides and protein aromatic residues.

Functional performance followed the structural changes. Both the emulsifying activity index and the emulsion stability index, measured with corn oil in a standardized homogenization assay, climbed steadily with stewing time in both groups, but the morel group maintained a consistently higher emulsifying activity index throughout. One transient exception appeared at the one-hour mark, where the stability index briefly dipped below the control’s, which the authors attribute to a competitive adsorption phase in which small, highly surface-active molecules temporarily displace larger macromolecular complexes. By the end of three hours, however, the emulsifying activity and stability indices of the morel group were elevated by 16.67 percent and 5.95 percent, respectively, compared with the control. Dynamic interfacial tension measurements using the pendant drop method corroborated these findings: all samples showed a typical biphasic decay over the 600-second measurement window, and the three-hour morel sample displayed the lowest equilibrium interfacial tension of any tested condition.

Microscopic imaging filled in the visual picture. Optical microscopy showed that during the first 15 to 30 minutes, only sparse, irregularly shaped particles were present in both groups. By one hour, particles had adopted a distinct spherical morphology but remained heterogeneous in size, and by three hours both groups produced abundant particles with more uniform distributions. From the one-hour point onward, however, the morel group’s particles were visibly smaller, denser, and more evenly dispersed. Confocal laser scanning microscopy, using Nile Blue A for proteins, Nile Red for lipids, and WGA-488 for polysaccharides, revealed a spatial arrangement consistent with a core-shell architecture: lipids localized predominantly in the inner core, while proteins and carbohydrates occupied the outer interfacial layer. In the morel group, early intense co-localization of protein and carbohydrate signals suggested that fungal polysaccharides rapidly complexed with dissolved proteins, and the final particles evolved into a notably finer and more homogeneous colloidal state.

The authors are careful to flag the limits of their mechanistic claims. The core-shell architecture is inferred from the spatial distribution of fluorescently labeled components together with interfacial tension and colloidal stability data, rather than from direct structural measurements. Direct validation of protein-polysaccharide binding using isothermal titration calorimetry or surface plasmon resonance, characterization of interfacial film mechanics through dilatational rheology, and imaging of the core-shell structure by cryo-SEM or TEM were not performed, and the authors state these techniques will be the focus of future work. All experiments were performed in at least triplicate, with data analyzed by one-way analysis of variance and Duncan’s multiple range test at a significance threshold of p less than 0.05. Within those constraints, the study offers a detailed, time-resolved account of how a single culinary addition, a handful of dried morels, can reshape the colloidal architecture of a traditional broth, suggesting a natural route to engineering more stable and nutritionally enriched food emulsions.

Subject of Research: How Morchella esculenta addition modulates colloidal micro/nano-particles and emulsifying properties in Tibetan chicken broth during stewing.

Article Title: Morchella esculenta reshapes colloidal micro/nano-particles to improve the emulsifying properties of Tibetan chicken broth

Article References: Dong, K., Zhao, C., Huang, X., Wu, Y., Song, H., An, F., Wu, Y., Song, X., Zhang, E., & Huang, Q. (2026). Morchella esculenta reshapes colloidal micro/nano-particles to improve the emulsifying properties of Tibetan chicken broth. Food Chemistry: X, 40, Article 104706. https://doi.org/10.1016/j.fochx.2026.104706

Image Credits: AI Generated

DOI: 10.1016/j.fochx.2026.104706

Keywords: Morchella esculenta, morel, Tibetan chicken broth, micro/nano-particles, emulsifying properties, colloid chemistry, protein-polysaccharide interactions, zeta potential, interfacial tension, core-shell structure, food emulsion, stewing