Hyaluronic Acid Molecular Weight Holds the Key to Slower-Melting, Firmer Ice Cream

Ice cream may look simple in the scoop, but it is one of the most structurally demanding products in the dairy aisle. A single spoonful contains a partially frozen emulsion in which air cells, fat globules, ice crystals, and a continuous aqueous phase must all coexist in delicate balance. Keeping that architecture stable through freezing, storage, and distribution is a constant battle against ice recrystallization, melting, and phase separation. For decades, manufacturers have relied on polysaccharide stabilizers such as guar gum, carrageenan, locust bean gum, and carboxymethyl cellulose to control moisture migration and preserve texture. Yet these ingredients can bring unwanted side effects, including excessive gumminess, which has pushed food scientists to explore alternative hydrocolloids with better functionality. A new study published in Food Science & Nutrition now suggests that an unlikely candidate, hyaluronic acid, could reshape how frozen desserts are formulated, and that the secret lies not just in using it, but in choosing the right molecular weight.

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