Hyaluronic acid, or HA, is a naturally occurring linear polysaccharide built from repeating disaccharide units of β-1,4-D-glucuronic acid and β-1,3-N-acetyl-D-glucosamine. Its structure carries a high negative charge density, allowing it to bind enormous amounts of water and form highly viscous solutions. That water-holding talent has already made HA famous in cosmetics and biomedical applications, and recent work has shown it can enhance water retention and structural properties in dairy products such as milk and processed cheese. Crucially, HA’s functionality depends strongly on its molecular weight. Commercial preparations span a vast range, from a few kilo-Daltons to more than 3000 kDa, with heavier chains generally delivering greater viscosity and more pronounced viscoelastic behavior. While HA is approved as a food ingredient in Japan, South Korea, China, and parts of the European Union, the US Food and Drug Administration has not yet cleared it as a general food additive across all categories, a regulatory reality that any future commercialization would need to navigate.

Researchers at South Dakota State University set out to answer a question that had not been systematically addressed: how does the molecular weight of HA affect the physicochemical and rheological properties of ice cream when it replaces a conventional stabilizer? The team prepared five formulations. The control batch contained 0.3% of a commercial stabilizer-emulsifier blend, a mixture of guar gum, mono- and diglycerides, locust bean gum, carrageenan, and polysorbate 80 standardized with dextrose. Four treatment batches substituted 0.3% HA at molecular weights of 320, 980, 1550, and 2550 kDa, with no added emulsifiers. The base recipe was identical across all batches: 33.92% cream, 41.8% skim milk, 5.89% non-fat dry milk, 14.8% sugar, and 3.29% dry corn syrup, yielding approximately 12.2% fat, 4.1% protein, 11.2% milk solids-not-fat, and 41.8% total solids. Each 2000-gram batch was blended, pasteurized at 85°C for 20 seconds, aged overnight at 4°C, churned in a batch freezer for 15 minutes, and hardened at −20°C for at least 24 hours.

The first hint that molecular weight mattered came during the aging period. The control mix and the mix containing the lowest molecular weight HA, 320 kDa, showed noticeably lower viscosity and slight visible separation, while the mixes with higher molecular weight HA remained homogeneous throughout. To quantify this, the researchers measured the creaming index, a key indicator of emulsion stability in which higher values signal greater phase separation of fat from the aqueous phase. Samples were stored at 4°C for 21 days and assessed at 7-day intervals. A two-way analysis of variance revealed a significant interaction between treatment and storage time, meaning the formulations changed at different rates. By day 21, the control and the 320 kDa sample had creaming indices exceeding 40%, whereas the mixes containing 1550 and 2550 kDa HA maintained substantially lower values, with the 2550 kDa formulation showing minimal creaming even after three weeks of storage.

Rheological measurements told a strikingly consistent story. Using an Anton Paar MCR 92 rheometer at 4°C, the team tracked the storage modulus G′, which reflects elastic, solid-like behavior, and the loss modulus G″, which reflects viscous, liquid-like behavior, across an angular frequency range of 0.1 to 62.8 rad/s at a strain of 0.5% within the linear viscoelastic region. Both moduli increased with frequency in all samples, confirming typical viscoelastic behavior, but the magnitude scaled directly with HA molecular weight. The 2550 kDa mix recorded the highest moduli, followed by 1550 and 980 kDa, while the 320 kDa mix and the control sat significantly lower. Apparent viscosity, measured over shear rates from 0.1 to 200 s⁻¹, followed the same hierarchy, with the 2550 kDa mix the most resistant to flow and the control the least. The researchers attribute these trends to the greater water-binding capacity and enhanced intermolecular interactions of longer polymer chains, while noting that the underlying mechanisms were not directly measured in this study.

When it came to the finished ice cream, one parameter remained stubbornly unaffected: overrun, the percentage of air incorporated during freezing, which governs whether a product tastes light and fluffy or dense and creamy. Values ranged only from 29.20% to 30.86%, with no statistically significant differences among treatments. The researchers suggest the relatively low overrun across the board likely reflects the limited air incorporation efficiency of the small-scale batch freezer used. The practical takeaway is still meaningful: adding HA at any molecular weight did not impair air incorporation, meaning the ingredient can be introduced without disrupting one of the most sensitive steps in ice cream production.

Texture, however, was a different matter. In penetration tests conducted with a TA.XT2 Texture Analyzer at −20°C, hardness differed significantly with HA molecular weight. The control and the 320 kDa sample were significantly softer than the ice creams made with 980, 1550, and 2550 kDa HA, which formed a statistically indistinguishable harder group. This suggests that HA with a molecular weight of at least 980 kDa is associated with increased firmness, plausibly through enhanced water binding and greater structural organization within the frozen matrix, though potential hydrogen bonding interactions and effects on ice crystal mobility remain unconfirmed hypotheses. Adhesiveness, by contrast, showed no significant differences among treatments; all samples displayed negative values indicating cohesive behavior. For consumers, the hardness findings point toward a potential trade-off, since firmer ice cream resists deformation during storage but may require slightly more effort to scoop straight from the freezer.

Perhaps the most commercially compelling result concerned melting behavior. Half-sphere samples of 100 grams, initially at −15°C, were placed on a wire screen in a 25°C chamber, and drip loss was recorded every 15 minutes for three hours. The ice creams containing 1550 and 2550 kDa HA melted significantly more slowly than both the 320 kDa sample and the control. This thermal resilience likely stems from the higher serum-phase viscosity and water-binding capacity of the long-chain polysaccharide, which appears to slow structural collapse as the product transitions from solid to liquid. Similar behavior has been reported in other ice cream systems containing polysaccharides, particularly those with elevated serum viscosity. For a product that increasingly spends time in delivery trucks, freezer aisles, and consumers’ shopping bags, a slower-melting formulation carries obvious logistical and sensory appeal.

The authors are careful to frame their conclusions within an important limitation. The control formulation contained both stabilizers and emulsifiers, while the HA treatments contained neither emulsifiers nor conventional stabilizers, so the observed differences cannot be attributed to stabilizer type alone. The study was designed to evaluate HA as a stabilizing ingredient, not to demonstrate full replacement of conventional stabilizer-emulsifier systems, and the researchers explicitly caution against interpreting the results as direct equivalence. Emulsifiers are known to influence fat destabilization, air incorporation, and network formation, all of which could have shaped the comparison. Future work with matched emulsifier systems, along with microstructural and sensory analyses, will be needed to establish whether HA can truly stand in for the established ingredient toolkit.

Even with those caveats, the study delivers a clear and quantifiable message: in frozen dairy desserts, the molecular weight of hyaluronic acid is not a detail but a design variable. At 320 kDa, HA offered little structural benefit, performing no better than the conventional stabilizer in most respects. At 980 kDa and above, and especially at 1550 and 2550 kDa, it was associated with firmer texture, slower melting, lower creaming indices, and stronger viscoelastic moduli, painting a picture of a more stable and cohesive matrix. As the food industry searches for hydrocolloids that combine functionality with clean-label appeal, and as regulatory pathways for HA in foods continue to evolve in major markets, this work suggests that the next generation of ice cream may be engineered not just by what is added, but by how heavy each polymer chain is. For a dessert that has been refined for over a century, the humble scoop may still have surprises left in its molecular structure.

Subject of Research: Effect of hyaluronic acid molecular weight on the physicochemical and rheological properties of ice cream

Article Title: Effect of Hyaluronic Acid Molecular Weight on Physicochemical and Rheological Properties of Ice Cream

Article References: Joshi, R., Hamouda, M. E. A., & Salunke, P. (2026). Effect of Hyaluronic Acid Molecular Weight on Physicochemical and Rheological Properties of Ice Cream. Food Science & Nutrition, 14(10), Article e72444. https://doi.org/10.1002/fsn3.72444

Image Credits: AI Generated

DOI: 10.1002/fsn3.72444

Keywords: hyaluronic acid, ice cream, molecular weight, rheology, food stabilizers, dairy science, emulsion stability, melting rate, viscosity, texture analysis, polysaccharides, food science

The research, led by Haoran Wang and colleagues, compared superheated steam treatment at 140, 160, and 180 degrees Celsius against two conventional pretreatments, steaming and stir-frying, using kernels of the Zangqing 320 cultivar from Tibet. Before treatment, the kernels were tempered to 20 percent moisture and equilibrated for six hours, then exposed to the steam for just six minutes. Conventional steaming required thirty minutes, and stir-frying involved twelve hours of soaking followed by thirty minutes of roasting at 160 degrees Celsius. The treated kernels were milled into whole flour, and gels were prepared from a 15 percent flour suspension heated at 95 degrees Celsius and cooled overnight.

The centerpiece of the investigation was beta-glucan, the soluble fiber responsible for many of barley’s health benefits. Using high-performance size-exclusion chromatography coupled with multi-angle laser light scattering, the team measured the weight-average molecular weight of beta-glucan isolated from both flour and gel. Native flour beta-glucan came in at 1.61 by ten to the fifth grams per mole. Every thermal treatment raised that figure, but superheated steam did so most dramatically: at 180 degrees Celsius the molecular weight climbed to 2.23 by ten to the fifth, the highest of any treatment. This finding runs counter to several earlier studies in which roasting, microwave heating, and oven baking depolymerized barley beta-glucan. The authors attribute the difference to moisture conditions and heating intensity. Tempering the kernels before treatment appears to shield the fiber from thermal degradation, while the rapid heat transfer and short exposure time of superheated steam limit chain scission.

The structural consequences extended well beyond beta-glucan. Fourier transform infrared spectroscopy revealed that gels made from steam-treated flour at 160 and 180 degrees Celsius showed increased short-range order in starch, reflected in a higher ratio of absorbance at 1047 to 1022 wavenumbers. Interestingly, this contrasts with the team’s own previous work on isolated starch, where the harshest steam treatment disrupted crystalline order most severely. In the whole-flour gel matrix, the researchers conclude, amylose and amylopectin chains released during gelatinization apparently reassociate into more ordered local domains upon cooling. Protein conformation shifted in parallel: as steam temperature rose, alpha-helix and beta-turn contents increased while beta-sheet and random coil proportions declined, signaling a partial rearrangement of the protein network.

Microscopy told a visually striking story. Scanning electron micrographs of the native gel revealed large, irregular pores, whereas gels from kernels treated at 160 degrees Celsius displayed a markedly more uniform morphology with smaller apparent pores. Confocal laser scanning microscopy, with starch stained green and protein red, showed that the numerous large dark voids of the native gel nearly vanished after treatment, with 160 degrees Celsius producing the most homogeneous starch-protein distribution. Push the temperature to 180 degrees Celsius, however, and the benefit reverses: larger, more irregular voids reappear alongside pronounced protein aggregation, indicating that excessive treatment intensity introduces new heterogeneity into the matrix.

Water behavior tracked these structural changes closely. Low-field nuclear magnetic resonance resolved three water populations in the gels, corresponding to bound, immobilized, and free water, with free water dominating at more than 95 percent of the total. Treatment at 160 and 180 degrees Celsius significantly increased the bound-water fraction, and all treatments raised the immobilized fraction, indicating a shift toward water populations with lower mobility. The effect was stronger for superheated steam than for conventional steaming or stir-frying. The authors suggest that higher molecular weight beta-glucan can retain water through hydrogen bonding, contributing to this immobilization, although at 180 degrees Celsius the bound and immobilized fractions dipped slightly, possibly because severe treatment depolymerizes starch chains that would otherwise hold water.

Texture analysis translated these molecular shifts into measurable mechanical differences. Springiness, the ability of a gel to recover after compression, responded most strongly to treatment: every thermal pretreatment increased it significantly, and the 160-degree steam sample achieved the highest value at 2.73 millimeters, up from 2.18 millimeters in the native gel. That peak springiness coincided with the most uniform pore structure and the lowest water mobility, painting a coherent picture of a gel whose architecture resists deformation and rebounds efficiently. Hardness, cohesiveness, and gumminess, by contrast, changed little across treatments, and only stir-frying produced a hardness significantly different from the control.

Rheology added nuance to the texture story. During temperature sweeps, all treated samples showed higher storage and loss moduli than the native gel, with the 140-degree sample exhibiting the strongest small-deformation viscoelastic response. In frequency sweeps, all gels behaved as elastic-dominant materials, with the storage modulus exceeding the loss modulus and the loss factor remaining below one across the tested range. The apparent tension between the highest springiness at 160 degrees and the highest modulus at 140 degrees reflects the different deformation regimes of the two measurements: the modulus was recorded at 1 percent strain within the linear viscoelastic region, while springiness measures recovery after 30 percent compression. Different regimes, the authors note, probe different aspects of the same heterogeneous network.

Perhaps the most consequential result concerns digestion. In vitro hydrolysis with pepsin, pancreatic alpha-amylase, and amyloglucosidase showed that superheated steam treatment reduced both rapidly and slowly digestible starch while boosting resistant starch, with the effect strengthening as temperature rose. At 180 degrees Celsius, resistant starch reached 15.87 percent, up from 8.78 percent in the native gel, while the estimated maximum digestibility fell from 93.40 percent to 87.59 percent. A logarithm-of-slope analysis split digestion into fast and slow phases and showed that treatment mainly suppressed hydrolysis during the first thirty minutes, consistent with the drop in rapidly digestible starch. Stir-frying, by contrast, barely moved the needle, leaving resistant starch essentially unchanged.

The authors propose that three concurrent changes explain the slowed digestion: greater starch short-range order, which produces compact hydrogen-bonded structures with reduced enzyme accessibility; elevated beta-glucan molecular weight, which increases viscosity and hinders enzyme diffusion; and protein aggregation, which adds a further physical barrier. Notably, the whole-flour gel digested more slowly than the isolated starch examined in the team’s earlier work, underscoring that non-starch components matter enormously in real foods. The practical upshot is a kind of dial: processors seeking better gel uniformity and elastic recovery could choose steam at 160 degrees Celsius, while those prioritizing slower starch digestion might opt for 180 degrees. For a gluten-free grain struggling to enter modern staple foods, a six-minute steam treatment that simultaneously improves texture and nutritional profile is a compelling proposition, and one that could reshape how ancient plateau cereals reach contemporary tables.

Subject of Research: Effect of superheated steam treatment on beta-glucan, gel structure, and starch digestibility in highland barley whole flour

Article Title: Effect of superheated steam treatment on endogenous β-glucan and gel properties of highland barley whole flour: Changes in gel structure and starch digestibility

Article References: Wang, H., Ma, T., Wang, L., Wang, L., Li, Y., & Qiu, J. (2026). Effect of superheated steam treatment on endogenous β-glucan and gel properties of highland barley whole flour: Changes in gel structure and starch digestibility. Food Chemistry: X, 39, Article 104557. https://doi.org/10.1016/j.fochx.2026.104557

Image Credits: AI Generated

DOI: 10.1016/j.fochx.2026.104557

Keywords: highland barley, superheated steam, beta-glucan, starch digestibility, resistant starch, gel properties, food processing, whole flour, rheology, molecular weight, Qinghai-Tibet Plateau, functional foods

The review, led by Cunchao Zhao and colleagues, introduces a framework the authors call ESAR, short for Extraction–Structure–Activity Relationship. The central idea is deceptively simple: extraction conditions determine molecular structure, and molecular structure determines biological function. Yet the authors contend that decades of mushroom polysaccharide research have treated these three dimensions separately, with extraction specialists optimizing yields, chemists cataloging compositions, and pharmacologists screening activities, all without cross-linking the data needed to reveal causal, predictive relationships. The result, they argue, is a field that has remained largely descriptive rather than mechanistic.

To build the framework, the team searched Web of Science and Google Scholar for English-language studies published between 2020 and 2025, retrieving roughly 1,800 records. After screening and deduplication, about 206 studies were retained for qualitative synthesis, with inclusion contingent on analytical validation by at least two orthogonal techniques such as nuclear magnetic resonance spectroscopy, FTIR, gas chromatography–mass spectrometry, or size-exclusion chromatography coupled with multi-angle light scattering. The synthesis maps how processing variables, including pH, temperature, ionic strength, solvent type, and extraction time, feed into structural outputs such as monosaccharide composition, glycosidic linkages, molecular weight, and higher-order conformation, and how those outputs in turn govern biological effects.

The structural stakes are considerable. Most mushroom polysaccharides are dominated by glucose, mannose, and galactose, with rarer sugars such as fucose, rhamnose, arabinose, and xylose modulating heterogeneity. Mild hot-water extraction tends to enrich glucose-heavy beta-glucans, which primarily drive immune activation through the Dectin-1 receptor, whereas alkaline or enzyme-assisted routes recover more mannans and other heteropolymers that often correlate with antioxidant activity. Excess heat or acid can selectively strip away deoxy sugars or depolymerize the chains entirely. In one cited example, monosaccharide composition remained stable at 79 degrees Celsius for three hours, but extraction above 100 degrees Celsius produced clear compositional shifts and a marked loss of beta-glucan branching.

Molecular weight emerges as another dialable quality attribute, and the review is emphatic that the popular assumption that smaller is always better does not hold. Low-molecular-weight fragments penetrate cells more efficiently and can trigger reactive-oxygen-dependent apoptosis in cancer cells, while high-molecular-weight polymers achieve multivalent receptor clustering that supercharges immune signaling. Lentinan from shiitake, extracted with hot water, retains a triple-helical beta-glucan structure in the 4 to 60 kilodalton range that engages Dectin-1 and complement receptor 3 to stimulate cytokine release. Yet alkaline extraction of Phellinus linteus mycelia yielded a polysaccharide of roughly 343 kilodaltons with potent anti-proliferative and hepatoprotective effects, and a 336-kilodalton polysaccharide from Lentinus velutinus killed HeLa and HepG2 cancer cells while sparing normal cells. Mid-range polymers between roughly 20 and 40 kilodaltons, such as fractions from Helvella leucopus and Hypsizygus ulmarius, consistently combine solubility with receptor accessibility.

To make such comparisons meaningful across methods as different as hot water, deep eutectic solvents, ultrasound, microwave, and subcritical water, the authors introduce a standardized hardness index that quantifies extraction severity. Thermal treatments are scored in degree-hours, chemical treatments in molarity-hours, and physical intensification in watt-hours or megapascal-hours. The index reveals, for example, that subcritical water at 140 to 180 degrees Celsius drives auto-hydrolysis that slashes molecular weight to around 2 kilodaltons, while ionic liquids disrupt hydrogen bonding and swell cell walls to release intact 500-kilodalton beta-glucans. A table mapping dozens of species, from Ganoderma lucidum to Poria cocos, links each extraction condition to the resulting structure and activity, providing what amounts to a recipe book for tailoring polysaccharides to specific applications.

Conformation adds a further layer of control. Triple-helical conformations, generally preserved by hot-water or enzyme-assisted extraction, strengthen multivalent binding to immune receptors and are consistently associated with potent immunomodulation, activating signaling cascades through NF-kappaB and MAPK pathways. Ultrasound and microwave treatment can uncoil those helices, exposing side chains that sometimes strengthen radical scavenging but weaken Dectin-1 recognition. Chemical modification tells the same story in reverse: DMSO and alkali transform lentinan’s triple helix into single chains and reduce its activity, but incorporating selenium nanoparticles restores helicity and enhances antitumor efficacy, while sulfonation partially recovers function through charged-group interactions with immune receptors.

The framework’s predictive power is most striking in the immunology and metabolism chapters. Beta-(1,3)-glucans with beta-(1,6) branches from shiitake, reishi, and Dictyophora indusiata show the strongest macrophage and cytokine activation, whereas linear alpha-(1,4) or beta-(1,4) polysaccharides from some Pleurotus and Auricularia species yield milder antioxidant or prebiotic effects. In diabetes models, branched beta-glucans of moderate molecular weight enhance glucose uptake through GLUT4 translocation and PI3K/Akt activation, while gut microbiota studies show Morchella polysaccharides promoting beneficial Lactobacillus populations and Auricularia hydrolysates improving GLP-1 secretion. In obesity models, Pleurotus eryngii polysaccharides reduced fat deposition by upregulating LDL receptors, and Tremella fuciformis polysaccharides suppressed adipogenic transcription factors including PPAR-gamma and C/EBP-alpha.

Notably, the review challenges the assumption that purification always improves performance. Crude polysaccharides from Lepista nuda outperformed purified isolates in antioxidant assays, and complete deproteinization of lentinan extracts reduced interleukin-2 induction, pointing to synergistic contributions from co-extracted proteins and phenolics. The authors also flag persistent weaknesses in the literature: receptor activation is usually inferred rather than measured directly, helix preservation is rarely confirmed by circular dichroism or SAXS, and inconsistent calibration and assay protocols make cross-study comparison unreliable. Conflicting trends in antioxidant activity, with some studies favoring low-molecular-weight fractions and others high-molecular-weight ones, likely reflect these methodological inconsistencies rather than genuine biology.

The translational outlook is nonetheless substantial. Lentinan, schizophyllan, and the polysaccharopeptides PSK and PSP have already advanced to clinical use or evaluation as cancer adjuvants in Japan and China, and a meta-analysis of 52 randomized trials found lentinan combined with cisplatin improved outcomes in malignant pleural effusion. Beyond medicine, extraction-tailored polysaccharides are stabilizing emulsions, fortifying gluten-free baked goods, extending the shelf life of biodegradable curcumin-doped packaging films, and boosting probiotic viability in yogurt. The authors close with a playbook for the field: report processing parameters precisely, pair orthogonal structural analytics with mechanism-anchored bioassays on matched fractions, deliberately target molecular-weight sweet spots, and validate through adequately powered human studies. If adopted, they argue, ESAR could transform scattered correlations into predictive design rules, turning mushroom polysaccharide development from a search for active extracts into the engineering of process-defined polymer architectures for targeted therapeutic and nutritional ends.

Subject of Research: Process-programmed relationships between extraction methods, molecular structure, and bioactivity of edible and medicinal mushroom polysaccharides.

Article Title: Process-Programmed Extraction–Structure–Activity Relationships (ESAR) in edible and medicinal mushroom polysaccharides: a mechanistic and application-oriented framework

Article References: Zhao, C., Aaqil, M., He, R., Kamil, M., Zheng, J., Guo, Y., Zhang, Z., Nawaz, T., Zhang, F., You, L., & Tian, Y. (2026). Process-Programmed Extraction–Structure–Activity Relationships (ESAR) in edible and medicinal mushroom polysaccharides: a mechanistic and application-oriented framework. Journal of Advanced Research, 87, 1045-1077. https://doi.org/10.1016/j.jare.2025.12.040

Image Credits: AI Generated

DOI: 10.1016/j.jare.2025.12.040

Keywords: mushroom polysaccharides, extraction methods, structure–activity relationships, beta-glucans, immunomodulation, antitumor activity, antioxidant, molecular weight, triple helix, gut microbiota, antidiabetic, functional foods