Structure, Properties, and Mechanisms of Powdered Fragrances and Fragrance Delivery Materials: Stability, Release Mechanisms, and Selection Logic
Structure, Properties, and Mechanisms of Powdered Fragrances and Fragrance Delivery Materials: Stability, Release Mechanisms, and Selection Logic
1 The Nature of Powdered Fragrances
1.1 What Is a Powdered Fragrance?
The essence of a powdered fragrance is to use a liquid fragrance as the aromatic core and immobilize fragrance molecules within a solid carrier, wall-material matrix, or capsule structure through adsorption, embedding, inclusion, or encapsulation. The result is a composite fragrance raw material with powder-processing properties, stabilization capability, and controlled-release functionality.
Liquid fragrances are typically composed of many types of fragrance molecules, including alcohols, aldehydes, ketones, esters, lactones, terpenes, phenol ethers, nitrogen- and sulfur-containing aroma chemicals, as well as macrocyclic musks, polycyclic musks, woody aromatic compounds, and others. Different fragrance molecules vary significantly in molecular weight, vapor pressure, polarity, functional groups, and chemical stability. Without structural treatment, liquid fragrances are prone to volatilization loss, oxidative deterioration, uneven dispersion, oil bleeding, migration, and changes in aroma proportions.
The value of powdered fragrances lies in altering the physical state of fragrance molecules through carrier structures, transforming them from a “freely volatile state” into a “migration-restricted state.” This change determines the storage stability, aroma release rate, and odor performance of the fragrance during use.
1.2 The Core of Powdered Fragrances Is the Structural Immobilization of Fragrance Molecules
Core Question | Corresponding Structural Factors | Properties Determined |
How is the fragrance immobilized? | Pores, cavities, wall materials, shell layers | Fragrance loading, surface oil, powder stability |
How is the fragrance protected? | Oxygen barrier, moisture barrier, diffusion resistance | Volatilization loss, oxidative stability, storage stability |
How is the fragrance released? | Dissolution, diffusion, desorption, rupture, inclusion equilibrium | Top-note impact, diffusion, sustained release, and long-lasting aroma performance |
2 Formation Methods of Powdered Fragrances
2.1 Adsorption, Embedding, Inclusion, and Encapsulation
The transformation of a liquid fragrance into a powdered fragrance is essentially the process by which fragrance oil is carried by a solid structure and its migration is restricted. Common formation methods include physical adsorption, matrix embedding, molecular inclusion, and core–shell encapsulation.
Formation Method | Location of Fragrance | Main Mode of Action | Representative Structures |
Physical adsorption | Inside pores and on particle surfaces | Capillary action, van der Waals forces, hydrogen bonding, hydrophobic interactions | Porous silica, porous starch, zeolites |
Matrix embedding | Inside a solidified wall-material network | Emulsified dispersion, film formation and solidification, glassy-state immobilization | Maltodextrin, gum arabic, modified starch |
Molecular inclusion | Inside the cavities of cyclic molecules | Hydrophobic-cavity inclusion, host–guest interaction | β-cyclodextrin and its derivatives |
Core–shell encapsulation | Inside the liquid oil core | Polymer-shell coating, interfacial film formation | Polyurea, polyurethane, acrylic microcapsules |
2.2 Different Formation Methods Correspond to Different Release Pathways
The release of a powdered fragrance is the process by which the fragrance changes from an immobilized state back into a freely migrating state.
Structural Type | Main Release Pathway | Release Characteristics |
Porous adsorption type | Desorption + pore diffusion | Relatively direct release, strongly affected by pore size and adsorption strength |
Matrix-embedded type | Release after wall-material hydration, softening, or dissolution | Pronounced release upon contact with water; affected by wall-material hygroscopicity |
Cyclodextrin inclusion type | Release after a shift in inclusion equilibrium | Mild release with molecular selectivity |
Microcapsule type | Diffusion, shell rupture, or permeability change | Can achieve delayed release or triggered release |
Zeolite molecular-sieve type | Pore desorption + molecular-sieve diffusion | Relatively slow release with strong selectivity |
3 Structure, Properties, and Mechanisms of Representative Raw Materials
3.1 Porous Silica Carriers
Porous silica is a common adsorption-type carrier used in powdered fragrances. Its main structure consists of a Si—O—Si network, with internal pore channels and a relatively high specific surface area. After fragrance oil enters the pores, it is affected by surface interactions with the pore walls and spatial confinement, changing from a free liquid into an adsorbed state.
3.1.1 Structural Features
The key structural parameters of porous silica include specific surface area, pore volume, pore-size distribution, surface hydroxyl density, and particle size.
Structural Parameter | Effect on Fragrance Performance |
Specific surface area | Determines the surface space available for fragrance adsorption |
Pore volume | Affects the upper limit of fragrance loading |
Pore-size distribution | Affects the entry, retention, and release rate of fragrance molecules |
Surface hydroxyl density | Affects adsorption strength toward polar fragrance molecules |
Particle size | Affects powder flowability, dispersibility, and dusting risk |
When the pore size is too small, larger molecules have difficulty entering the pores, limiting fragrance loading. When the pore size is too large, fragrance immobilization is insufficient, making early-stage volatilization loss more likely. An appropriate pore-size distribution helps balance fragrance loading and release rate.
3.1.2 Performance Characteristics
The main advantages of porous silica carriers are strong oil-absorption capacity, clear powdering effect, and relatively simple processing. They are suitable for converting hydrophobic liquid fragrances into powder raw materials that are easy to measure, mix, and disperse. Their limitation is that porous silica mainly immobilizes fragrances through adsorption and does not form a fully enclosed structure. Fragrance molecules may still gradually migrate along the pores to the outside of the particles.
Different silica carriers vary significantly in structure. Mesoporous silica and silica gel emphasize the role of pore channels and pore volume, while fumed silica relies more on high specific surface area, surface hydrophobicity, and particle aggregation structure to achieve oil absorption, anti-caking effects, and surface-oil control.
3.1.3 Mechanism of Action
The action of porous silica on fragrances can be summarized as:
Pore adsorption → restricted diffusion → surface desorption → volatile release
After the fragrance enters the pores, its volatilization pathway is extended. Molecules migrating from the interior of the pores to the external environment must undergo diffusion and desorption. The release rate depends on the vapor pressure, molecular size, polarity, and pore-wall adsorption strength of the fragrance molecules. Highly volatile small molecules can migrate out of the pores more easily, resulting in a pronounced top-note effect. Low-volatility molecules or molecules that interact strongly with the pore walls are released more slowly and may enhance the later-stage aroma. When the fragrance formula contains an excessively high proportion of light components, porous adsorption-type powders may still show attenuation of top notes during storage.
3.2 Porous Starch Carriers
Porous starch is formed from natural starch through enzymatic hydrolysis, acid hydrolysis, or combined modification, resulting in a porous structure within the granules. Compared with inorganic silica, porous starch offers renewable sourcing, better biocompatibility, and a softer powder feel.
3.2.1 Structural Features
The basic framework of porous starch consists of amylose and amylopectin, and the molecules contain a large number of hydroxyl groups. The porous structure gives it the ability to adsorb fragrance oils, while the hydrophilicity of the starch framework determines its swelling and release behavior in the presence of moisture. The immobilization of fragrances by porous starch mainly arises from two types of interactions:
Type of Action | Specific Manifestation |
Pore adsorption | Fragrance enters the internal pores of the particles and is immobilized by capillary action |
Surface interaction | Starch hydroxyl groups form hydrogen-bonding or dipole interactions with certain polar fragrance molecules |
3.2.2 Performance Characteristics
The advantages of porous starch include mild sourcing, good powder feel, and a relatively low oily feel after adsorption. It is suitable for powdered fragrance designs that require natural sourcing, pleasant powder touch, or mild release. Its drawbacks are that moisture resistance and thermal stability are usually inferior to those of inorganic porous materials. After moisture absorption, starch particles may swell, the pore structure may change, fragrance release may accelerate, and powder flowability may decrease.
3.2.3 Mechanism of Action
The release mechanism of porous starch has a clear moisture-responsive character. In the dry state, the fragrance is immobilized in the pores. When environmental humidity increases or the material comes into contact with water, the starch framework absorbs water and swells, the pore structure loosens, and fragrance molecules migrate out more easily. The mechanism can be summarized as:
Pore adsorption → moisture entry → starch swelling → fragrance desorption and release
The focus of porous-starch powdered fragrances is not strong sealing, but mild immobilization and moisture-promoted release through a naturally derived porous structure.
3.3 Maltodextrin–Gum Arabic Spray-Drying Wall Materials
Spray-dried powdered fragrances usually use composite wall-material systems such as maltodextrin, gum arabic, modified starch, proteins, or polysaccharides. The preparation process generally includes emulsification, homogenization, and spray drying. The fragrance oil is first dispersed into fine oil droplets, then embedded in a solidified wall-material matrix, and finally formed into powder particles.
3.3.1 Structural Features
Maltodextrin has good glassy-state solidification ability, low viscosity, and matrix-filling functionality, but weak emulsifying ability. Gum arabic has good emulsion-stabilizing and interfacial-adsorption capabilities, but its cost is relatively high. When the two are combined, gum arabic mainly stabilizes the oil–water interface, while maltodextrin mainly forms the continuous solid matrix after drying.
Component | Main Function |
Fragrance oil | Aroma source |
Gum arabic | Emulsification, interfacial stabilization, reduction of oil-droplet coalescence |
Maltodextrin | Matrix filling, viscosity reduction, formation of a glassy solid matrix |
Moisture | Affects glass-transition temperature, caking, and release rate |
3.3.2 Performance Characteristics
The advantages of spray-dried powdered fragrances are good dispersibility in water, mature production technology, and relatively high powder uniformity. They are suitable for preparing fragrance powders with good dispersibility.
Their shortcomings mainly arise from two aspects. First, hot-air drying is involved in the spray-drying process, and highly volatile aroma chemicals may be lost, resulting in differences between the aroma of the powdered fragrance and that of the original liquid fragrance. Second, most wall materials are hydrophilic carbohydrates. After moisture absorption, the glass-transition temperature may decrease, leading to caking, adhesion, or premature release.
3.3.3 Mechanism of Action
The protective effect of spray-dried powdered fragrances comes from the spatial restriction imposed on fragrance oil droplets by the solid matrix. In the dry state, the wall material is in a high-viscosity or glassy state, and the diffusion rate of fragrance molecules is relatively low. After contact with moisture, the wall material absorbs water and softens, swells, or dissolves, causing fragrance oil droplets to be re-exposed and released. The release process can be summarized as:
Emulsified dispersion → wall-material solidification → matrix-restricted diffusion → water-induced softening/dissolution → fragrance release
The key to spray-dried powdered fragrances is the change in wall-material state. The emulsifying ability, glass-transition temperature, hygroscopicity, and film-forming capacity of the wall material jointly determine fragrance retention and release behavior.
3.4 Octenyl Succinic Anhydride Modified Starch Wall Material
Octenyl succinic anhydride modified starch is commonly abbreviated as OSA modified starch. It is an amphiphilic modified starch obtained by introducing hydrophobic octenyl succinate groups onto starch molecules.
3.4.1 Structural Features
Ordinary starch is mainly composed of a hydrophilic glucose backbone and lacks the ability to effectively stabilize oil–water interfaces. After OSA modification, the molecule contains both hydrophilic starch segments and hydrophobic octenyl segments, enabling it to adsorb at the interface between fragrance oil droplets and the aqueous phase, reduce interfacial tension, and form a stable emulsifying layer.
Structural Part | Performance Contribution |
Starch backbone | Film formation, thickening, formation of a dried matrix |
Hydroxyl groups | Provide hydrophilicity and water dispersibility |
Octenyl hydrophobic chains | Adsorb onto the oil phase and enhance emulsifying ability |
Succinate ester linkage structure | Connects the hydrophobic chain with the starch backbone |
3.4.2 Performance Characteristics
OSA modified starch functions as both an emulsifier and a wall material. It can reduce the need for additional emulsifiers and improve the stability of fragrance oil droplets in the emulsion before spray drying. When the wall-material ratio and drying conditions are appropriate, improved emulsion stability usually helps reduce surface oil after drying and improve aroma retention. Compared with maltodextrin, OSA modified starch has stronger affinity for the fragrance oil phase. Compared with gum arabic, OSA modified starch can be used as an alternative or co-wall material to improve emulsion stability, batch controllability, and cost control. However, its specific suitability still needs to be evaluated together with target regulations, product positioning, and the formulation system.
3.4.3 Mechanism of Action
The key action of OSA modified starch occurs at the oil–water interface. The hydrophobic octenyl segments insert into the fragrance oil droplets, while the hydrophilic starch segments extend into the aqueous phase, forming a steric barrier layer that inhibits oil-droplet coalescence. After spray drying, the fragrance oil droplets are immobilized within the starch matrix. The mechanism can be summarized as:
Interfacial adsorption → oil-droplet stabilization → drying and solidification → matrix protection → water-triggered release
The core advantage of OSA modified starch is that it controls the final powder’s aroma retention, surface oil, and release stability through emulsion-structure control.
3.5 Cyclodextrin Inclusion Materials
Cyclodextrin, abbreviated as CD, is a cyclic oligosaccharide formed by glucose units linked through α-1,4-glycosidic bonds. Common types include α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin. Among them, β-cyclodextrin, abbreviated as β-CD, is widely used in fragrance inclusion.
3.5.1 Structural Features
Cyclodextrin molecules have a cyclic cavity structure that is “hydrophilic on the outside and hydrophobic on the inside.” The external hydroxyl groups allow contact with the aqueous phase, while the internal hydrophobic cavity can accommodate fragrance molecules of suitable size and hydrophobicity.
Cyclodextrin Structural Part | Performance Contribution |
External hydroxyl groups | Provide hydrophilicity and powder dispersibility |
Internal hydrophobic cavity | Includes hydrophobic fragrance molecules |
Cavity size | Determines the types of molecules that can be included |
Host–guest stability constant | Determines the ease of release |
The cavity size of β-CD is suitable for many small- to medium-sized fragrance molecules, but not all aroma chemicals are suitable for inclusion. When the molecule is too large, the molecular configuration does not match, or the polarity is too strong, inclusion efficiency decreases. Natural β-CD has limited water solubility. When the objective is to improve aqueous dispersibility or release efficiency, derivatives such as 2-hydroxypropyl-β-CD and methyl-β-CD usually offer greater advantages.
3.5.2 Performance Characteristics
The most distinctive feature of cyclodextrin-included fragrances is molecular-level immobilization. Rather than simply adsorbing the fragrance onto the particle surface, the fragrance molecule enters the hydrophobic cavity of cyclodextrin and forms a host–guest inclusion complex.
This structure can reduce the free volatilization of fragrance molecules, improve the aqueous dispersibility of certain aroma chemicals, and under certain conditions improve their stability against light, oxygen, heat, or volatilization loss. Its limitations are limited inclusion capacity and selectivity toward the size and hydrophobicity of fragrance molecules. In complex fragrance formulations, different aroma chemicals have different binding abilities with cyclodextrin, which may change the aroma proportions during release.
3.5.3 Mechanism of Action
The release of cyclodextrin-included fragrances is controlled by inclusion equilibrium. Fragrance molecules exist in a dynamic equilibrium between the “inside of the cyclodextrin cavity” and the “external environment.” When the external fragrance concentration decreases, moisture increases, temperature rises, or competing guest molecules are present, the inclusion equilibrium shifts and the fragrance is gradually released. The mechanism can be summarized as:
Hydrophobic-cavity inclusion → reduction of free volatilization → change in external conditions → shift in inclusion equilibrium → fragrance release
The key function of cyclodextrin is not to form high-loading fragrance powders, but to control fragrance release through molecular recognition and reversible inclusion. It is suitable for fragrance raw-material designs that require strong control of volatility, odor softening, and stability.
3.6 Polymer Microcapsule-Type Fragrance Delivery Raw Materials
Polymer fragrance microcapsules are usually core–shell structures, with a liquid fragrance oil core inside and a polymer shell outside. Common shell materials include polyurea, polyurethane, melamine–formaldehyde resin, urea–formaldehyde resin, acrylic polymers, and biodegradable polymer shell materials developed in recent years. Polymer fragrance microcapsules are not necessarily supplied as dry powders; many products exist as aqueous dispersions, slurries, or emulsions.
3.6.1 Structural Features
The performance of microcapsules is jointly determined by the oil core, shell layer, and interfacial structure.
Structural Component | Key Function |
Fragrance oil core | Provides aroma and determines the fragrance profile and odor performance after release |
Polymer shell | Isolates the fragrance from the external environment and controls diffusion and release |
Shell thickness | Determines mechanical strength and release resistance |
Crosslinking density | Determines water resistance, surfactant resistance, and difficulty of rupture |
Particle-size distribution | Affects stability, deposition, and release uniformity |
Unlike adsorption-type powders, microcapsules physically isolate the fragrance oil core through a continuous shell layer. The denser the shell, the less premature fragrance leakage occurs, but the more difficult release triggering becomes. The thinner the shell or the lower the crosslinking density, the easier release becomes, but storage stability may decrease.
3.6.2 Performance Characteristics
The core advantages of polymer microcapsules are fragrance protection and triggered release. They can reduce direct contact between the fragrance and external moisture, oxygen, surfactants, or other formulation components during storage, thereby reducing aroma loss and unnecessary reactions.
Their shortcomings also arise from the shell structure. Improper shell-material selection may lead to premature capsule rupture, insufficient release, poor deposition, or reduced system stability. At the same time, polymer shell materials also require attention to biodegradability, residual monomers, formaldehyde-release risk, and regulatory applicability.
3.6.3 Mechanism of Action
The release mechanisms of microcapsules mainly include three types:
Release Mode | Mechanistic Description |
Diffusion release | Fragrance molecules slowly migrate outward through the shell layer |
Mechanical release | External force causes the shell to deform, crack, or rupture |
Environment-responsive release | Changes in humidity, temperature, pH, or medium alter shell permeability |
Among these, diffusion release determines baseline fragrance leakage during storage and in a static state. Mechanical release determines the intensity of aroma release after friction or pressure. Environment-responsive release is related to the hydrophilicity, crosslinking density, and chemical stability of the shell material.
3.7 Zeolite and Aluminosilicate Porous Carriers
Zeolites are crystalline aluminosilicates with regular microporous structures. Their framework is formed by linked SiO₄ and AlO₄ tetrahedra. Because aluminum–oxygen tetrahedra carry negative charges, exchangeable cations are usually present in the zeolite pores to maintain charge balance. Their regular pores, relatively high thermal stability, and adsorption selectivity allow them to serve as inorganic porous carriers for fragrance molecules.
3.7.1 Structural Features
The key difference between zeolites and ordinary porous silica lies in their crystalline pore regularity and molecular-sieve effect. Only fragrance molecules with suitable size, shape, and polarity can effectively enter the pores or be adsorbed at the pore openings.
Structural Feature | Effect on Fragrance Performance |
Regular micropores | Produce molecular-sieve selectivity |
Silicon–aluminum ratio | Affects hydrophilicity/hydrophobicity and adsorption strength |
Cation type | Affects adsorption capacity for polar molecules |
Pore size | Determines the range of fragrance molecules that can enter |
Crystal stability | Provides good thermal stability and powder stability |
3.7.2 Performance Characteristics
Zeolite carriers have good adsorption and sustained-release capability for small fragrance molecules. They are especially suitable for discussing pore selectivity, humidity response, and controlled release by inorganic carriers. Research on Y-type zeolite for the adsorption and sustained release of highly volatile fragrance molecules shows that zeolite pores can influence fragrance retention and release behavior through host–guest interactions.
Their limitation is relatively small pore size, which restricts compatibility with bulky fragrance molecules and complex fragrance oils. When a fragrance formula contains a high proportion of large-molecule fixative components, zeolites may mainly adsorb small-molecule components, causing the released aroma to differ from the original fragrance oil.
3.7.3 Mechanism of Action
Fragrance release from zeolites is mainly controlled by adsorption–desorption equilibrium and pore diffusion. After fragrance molecules enter the pores, their volatilization rate decreases due to spatial confinement and interactions with the pore walls. When external temperature, humidity, or competing adsorbed molecules change, the fragrance is gradually released from the pores. The mechanism can be summarized as:
Pore-selective adsorption → restricted molecular diffusion → change in external conditions → desorption and release
4 Underlying Mechanisms Behind the Performance of Powdered Fragrances
4.1 How Fragrance Molecules Are Immobilized
The first layer of performance in powdered fragrances comes from “immobilization.” The immobilization method determines where the fragrance exists in the powder and whether surface oil, oil bleeding, and volatilization during storage are likely to occur.
Immobilization Method | Representative Raw Materials | Immobilization Mechanism | Performance Characteristics |
Pore adsorption | Porous silica, porous starch, zeolites | Fragrance enters pores or adsorbs onto pore walls | Clear powdering effect; release controlled by pore size |
Matrix embedding | Maltodextrin, gum arabic, OSA modified starch | Fragrance oil droplets are dispersed in a solidified wall-material network | Good dispersibility; pronounced release upon contact with water |
Molecular inclusion | β-CD, hydroxypropyl-β-CD | Fragrance molecules enter hydrophobic cavities | Strong molecular selectivity; mild release |
Shell coating | Polyurea, polyurethane, acrylic shell materials | Fragrance oil core is isolated by a polymer shell | Strong protection; triggered release can be achieved |
Stronger immobilization is not always better. If immobilization is too weak, the fragrance is easily lost during storage. If immobilization is too strong, release during use may be insufficient. The key to powdered fragrance design is to balance stability and release.
4.2 How Fragrance Molecules Are Protected
The second layer of performance in powdered fragrances comes from “protection.” Many fragrance molecules contain double bonds, aldehyde groups, ester groups, or terpene structures and are easily affected by oxygen, light, heat, moisture, metal ions, or alkaline substances. Powdering, embedding, and inclusion cannot completely prevent oxidation, but they can reduce direct contact between the fragrance and the external environment, thereby improving oxidative stability.
Protection Method | Representative Structure | Principle of Action |
Reducing free volatilization | Porous carriers, cyclodextrins, microcapsules | Reduces the proportion of free fragrance molecules |
Restricting diffusion | Spray-dried matrix, polymer shell | Increases resistance to outward fragrance migration |
Isolating external components | Microcapsules, dense wall materials | Reduces contact between fragrance and moisture, oxygen, or surfactants |
Shielding sensitive structures | Cyclodextrin inclusion complexes | Hydrophobic cavity partially covers fragrance molecules |
It should be noted that the protective ability of powdered fragrances is affected by structural integrity. When surface oil is too high, wall materials absorb moisture, shells are damaged, or storage temperature is too high, fragrances may still undergo volatilization, oxidation, or changes in aroma proportions.
4.3 How Fragrance Molecules Are Released
The third layer of performance in powdered fragrances comes from “release.” Fragrance must migrate out of the carrier structure and enter the air or target medium before it can be perceived by the sense of smell. The release process is usually jointly determined by desorption, diffusion, dissolution, swelling, shell rupture, or shifts in inclusion equilibrium.
Release Mechanism | Corresponding Structure | Release Characteristics |
Desorption release | Porous silica, porous starch | Relatively direct release; affected by adsorption strength |
Pore diffusion | Silica, zeolites | Release rate affected by pore size and molecular size |
Wall-material dissolution release | Maltodextrin and gum arabic matrix | Pronounced release after contact with water |
Inclusion-equilibrium release | Cyclodextrin inclusion complex | Mild release; affected by temperature, moisture, and competing molecules |
Shell-rupture release | Polymer microcapsules | Can be triggered by friction, pressure, or environmental change |
Permeation-diffusion release | Microcapsule shell | Low-rate leakage may occur during storage |
4.4 Key Evaluation Indicators: Fragrance Loading, Surface Oil, and Release Curve
Indicator | Evaluation Significance |
Fragrance loading | Determines the effective fragrance content in the powder |
Surface oil | Determines whether the fragrance has been effectively adsorbed, embedded, or encapsulated |
Particle-size distribution | Determines powder flowability, dispersibility, and release uniformity |
Moisture content | Determines the risk of caking and premature release |
Aroma retention rate | Determines fragrance loss during the powdering process |
Release curve | Determines top-note impact, diffusion, and later-stage release |
Storage stability | Determines aroma changes under heat, humidity, and light |
Structural composition | Determines the contribution of wall materials, shell materials, and carriers to performance |
Compliance documentation | Determines IFRA, safety, allergen, and regulatory applicability |
High fragrance loading does not necessarily mean good performance. If surface oil is also high, it indicates that the fragrance has not been effectively immobilized, making volatilization, caking, and aroma attenuation more likely. A reasonable evaluation method is to assess fragrance loading, surface oil, aroma retention rate, and release curve together.
5 Advantages and Limitations of Powdered Fragrances
The advantages of powdered fragrances come from structural treatment, and their limitations also arise from the structure itself. Different structures solve different problems, so their quality cannot be judged simply by “strength of long-lasting aroma.”
Advantages Brought by Structure | Corresponding Limitations |
Converts liquid fragrance into powder, improving metering, mixing, and dispersion | Increased carrier proportion may reduce effective fragrance content |
Reduces the proportion of free fragrance and lowers volatilization loss | Highly volatile light components may still be lost during processing or storage |
Improves fragrance stability through wall materials, cavities, or shell layers | Wall-material moisture absorption, shell damage, or excessive surface oil can reduce stability |
Controls release through pores, matrices, inclusion complexes, or capsules | Different structures have different release mechanisms and cannot simply replace one another |
Improves compatibility between fragrance and powder systems, reducing oil bleeding and caking | Complex fragrance formulations may show changes in aroma proportions due to selective adsorption or inclusion |
Can be designed for water-triggered release, slow release, or triggered release | Cost, process complexity, and regulatory requirements increase accordingly |
6 Selection Logic for Powdered Fragrance Raw Materials
6.1 Selection Based on Fragrance Molecular Structure
When selecting powdered fragrance raw materials, the molecular size, vapor pressure, polarity, functional groups, and stability of the main aroma chemicals in the fragrance should first be analyzed. The molecular structure of the fragrance determines whether it is more suitable for “adsorption,” “inclusion,” or “encapsulation.” If molecular size, polarity, and volatility are ignored and powder fragrance selection is based only on fragrance type, aroma distortion or unexpected release behavior may occur.
Fragrance Molecular Characteristics | Suitable Structural Direction |
Small molecules with high volatility | Prioritize cyclodextrin, dense microcapsules, or pore-adsorption materials with suitable pore size and surface interactions |
Strong hydrophobicity | OSA modified starch, microcapsules, porous silica |
Moderate molecular size | Higher possibility of cyclodextrin inclusion |
Large molecules with low volatility | Porous adsorption or matrix embedding is more suitable |
Easily oxidized terpenes | Embedding, inclusion, or capsule protection is more valuable |
Complex compounded fragrances | Spray drying or microcapsules are more likely to preserve the overall fragrance profile |
6.2 Selection Based on Target Performance
Different powdered fragrance raw materials are suitable for solving different problems. Some powdered fragrances mainly solve processability issues, some mainly address stability, and others are mainly used for controlled release.
Target Performance | Preferred Raw-Material Structure |
Powdering of liquid fragrance | Porous silica, porous starch |
Reduction of surface oil | Spray-drying wall materials, OSA modified starch, microcapsules |
Improvement of water dispersibility | Maltodextrin, gum arabic, OSA modified starch, cyclodextrin |
Reduction of volatilization loss | Cyclodextrin, microcapsules, zeolites, porous silica |
Sustained release | Microcapsules, cyclodextrin, zeolites |
Improvement of fragrance protection | Microcapsules, spray-dried matrix, cyclodextrin |
Improvement of natural-origin attributes | Porous starch, starch-based wall materials, certain natural polymer shell materials |
6.3 Verification Based on Quality Indicators
The effectiveness of powdered fragrance raw materials should ultimately be verified through quality indicators to confirm whether the structure is truly effective. The following items are recommended as key points of attention:
Verification Item | Evaluation Focus |
Fragrance loading and surface oil | Determines whether the fragrance has effectively entered the carrier interior or been embedded |
Particle size and flowability | Determines compatibility with powder processing |
Moisture and hygroscopicity | Determines the risk of caking and premature release |
Aroma fidelity | Determines whether aroma proportions change before and after powdering |
Release curve | Determines release rate, release stages, and later-stage aroma |
Heat- and humidity-storage stability | Determines aroma loss under actual storage conditions |
Wall-material or shell-material composition | Determines structural source, safety, and regulatory applicability |
IFRA documentation | Based on the final fragrance formula, target product category, use concentration, and exposure scenario, determines safe-use restrictions, allergens, and regulatory applicability |
7 Representative Chemical Classification Tables Related to the Structure, Properties, and Mechanisms of Powdered Fragrances
Table 1. Porous Adsorption Carriers, Inorganic Pore-Channel Materials, and Moisture-Control Materials
Category | CAS No. | Aladdin Cat. No. | Name | Specification or Purity | Product Features and Applications |
Porous siliceous adsorption carrier | 61790-53-2 | D304166 | Diatomaceous earth | Filter aid | Porous siliceous structure; used for fragrance oil-phase adsorption, powder carrying, dispersibility, and flowability studies |
Hydrophobic silica carrier | 112945-52-5 | Fumed silica | Hydrophobic type, specific surface area (BET): 300 m²/g | Hydrophobic surface and high-specific-surface-area structure; used for fragrance oil adsorption, anti-caking, surface-oil control, and powder stability studies | |
Mesoporous silica carrier | 7631-86-9 | Silicon dioxide | Nanoparticles, mesoporous, outer diameter 450–550 nm, aperture 2–4 nm | Well-defined mesoporous structure; used for studies on pore-channel adsorption, diffusion release, and carrier structure–performance relationships of fragrance molecules | |
Moisture-control material | 112926-00-8 | S743367 | Indicating silica gel desiccant | Reagent grade | Used for moisture control during powdered fragrance storage, hygroscopic stability evaluation, and studies on the effect of moisture on release behavior |
Molecular-sieve aluminosilicate carrier | 1318-02-1 | Synthetic zeolite | Particle size ≤10.0 μm | Regular pore channels and molecular-sieve effect; used for adsorption of small-molecule aroma chemicals, selective retention, and sustained-release behavior studies | |
Layered silicate carrier | 1302-78-9 | Bentonite | Bentone SD-2, suitable for medium- to high-polarity solvents | Layered silicate structure; used for fragrance oil-phase adsorption, suspension stabilization, viscosity-structure formation, and release modulation studies | |
Aluminosilicate powder carrier | 1344-00-9 | Sodium aluminosilicate | ≥82% SiO₂ basis, based on calcined substance | Inorganic aluminosilicate powder; used for fragrance adsorption, powder dispersion, carrier blending, and storage stability studies |
Table 2. Matrix-Embedding Wall Materials, Natural Polymers, and Film-Forming Stabilizing Materials
Category | CAS No. | Aladdin Cat. No. | Name | Specification or Purity | Product Features and Applications |
Cationic polysaccharide wall material | 9012-76-4 | Chitosan | Medium viscosity, 200–400 mPa·s | Film-forming and ionic-crosslinking characteristics; used for natural polymer fragrance embedding, microparticle preparation, and humidity-responsive release studies | |
Polysaccharide gel wall material | 9005-38-3 | Sodium alginate, from brown algae | Medium viscosity | Can form gel networks with calcium ions; used for fragrance embedding, gel microparticle preparation, and water-triggered release studies | |
Protein-based wall material | 9000-70-8 | Gelatin | Suitable for microbiology, gel strength ~250 g Bloom | Has film-forming and gelling properties; used for fragrance complex coacervation embedding, capsule wall materials, and protein-based release-system studies | |
Nonionic emulsifying stabilizer | 9005-65-6 | Tween® 80 | Viscous liquid, preservative-free, low peroxide; low carbonyl | Used for fragrance oil-droplet emulsification, emulsion stabilization before embedding, and dispersion-system studies before spray drying | |
Water-soluble film-forming polymer | 9002-89-5 | Mowiol® PVA-124 polyvinyl alcohol (PVA) | Viscosity: 54–66 mPa·s | Film-forming and protective colloid material; used for fragrance microcapsule dispersion stabilization, auxiliary shell-layer film formation, and release modulation studies | |
Cellulose thickening wall material | 9004-32-4 | Sodium carboxymethyl cellulose (CMC) | Viscosity: 1000–1400 mPa·s, USP grade | Water-soluble cellulose derivative; used for fragrance emulsion thickening, suspension stabilization, matrix embedding, and water-dispersibility studies | |
Emulsifying embedding wall material | 9000-01-5 | Gum arabic | Pharmaceutical grade, PharmPure™, powder | Natural colloidal emulsifying wall material; used for fragrance oil-droplet stabilization, spray-drying embedding, and surface-oil control studies | |
Starch-based wall material | 9005-25-8 | S116028 | Corn starch | Pharmaceutical grade, PharmPure™ | Polysaccharide matrix material; used for porous starch preparation, fragrance adsorption, matrix embedding, and humidity-responsive release studies |
Cellulose film-forming wall material | 9004-65-3 | Hydroxypropyl methylcellulose (HPMC) | Substitution type 2910, viscosity: 400 mPa·s, methoxy: 28–30%; hydroxypropyl: 7.0–12% | Film-forming, thickening, and protective colloid material; used for fragrance embedding wall materials, release-resistance adjustment, and moisture-entry control studies | |
Carbohydrate wall material | 9050-36-6 | Maltodextrin | Dextrose equivalent 5.0–8.0 | Common matrix wall material for spray drying; used for fragrance oil-droplet solidification, glassy-state immobilization, and water-triggered release studies | |
Dispersing film-forming polymer | 9003-39-8 | Polyvinylpyrrolidone (PVP) | Average molecular weight 8000, K16–18 | Provides dispersion and film-forming functions; used for fragrance particle stabilization, embedding assistance, and powder blending studies | |
Hydrophobic cellulose wall material | 9004-57-3 | Ethyl cellulose (EC) | 18–22 mPa·s | Hydrophobic film-forming material; used for fragrance sustained-release coating, construction of diffusion resistance, and oil-phase release control studies | |
Polysaccharide gel wall material | 9000-69-5 | Pectin | Galacturonic acid, dry basis ≥74.0% | Polysaccharide gel material; used for fragrance embedding, hydrophilic matrix construction, and moisture-responsive release studies |
Table 3. Cyclodextrin Inclusion Materials
Category | CAS No. | Aladdin Cat. No. | Name | Specification or Purity | Product Features and Applications |
Cyclodextrin inclusion material | 128446-35-5 | 2-Hydroxypropyl-β-cyclodextrin | ≥98% | Water-soluble cyclodextrin derivative; used for inclusion, solubilization, volatilization control, and release-equilibrium studies of hydrophobic fragrance molecules | |
Cyclodextrin inclusion material | 128446-36-6 | Methyl-β-cyclodextrin (MβCD) | Average Mn 1310 | Substituted cyclodextrin material; used for fragrance molecule inclusion, hydrophobic-cavity interactions, and host–guest release studies | |
Cyclodextrin inclusion material | 10016-20-3 | α-Cyclodextrin | ≥98% (HPLC) | Small-cavity cyclodextrin material; used for inclusion of small-sized aroma chemicals, molecular matching, and volatilization behavior studies | |
Cyclodextrin inclusion material | 7585-39-9 | β-Cyclodextrin | ≥98% | Typical fragrance inclusion material; used for host–guest inclusion of aromatic molecules, powder immobilization, and sustained-release mechanism studies | |
Cyclodextrin inclusion material | 17465-86-0 | γ-Cyclodextrin | ≥98% | Large-cavity cyclodextrin material; used for inclusion of larger-sized aroma chemicals, cavity-size effect studies, and release-difference studies |
Table 4. Microcapsule Shell Materials, Potentially Biodegradable Polymer Shell Materials, and Encapsulation Supporting Raw Materials
Category | CAS No. | Aladdin Cat. No. | Name | Specification or Purity | Product Features and Applications |
Potentially biodegradable polymer shell material | 26780-50-7 | Resomer® RG 505, poly(D,L-lactide-co-glycolide) (PLGA) | Ester-terminated, Mw 54,000–69,000 | Potentially biodegradable polyester material; used for fragrance microcapsule shells, sustained-release particles, and degradation-controlled release behavior studies | |
Potentially biodegradable polymer shell material | 24980-41-4 | Resomer® C 209, polycaprolactone (PCL) | Ester-terminated | Hydrophobic biodegradable polyester material; used for fragrance embedding, diffusion-based sustained release, and polymer shell-material studies | |
Amino resin shell precursor | 57-13-6 | Urea | AR, ≥99% | Urea–formaldehyde resin shell precursor; used for fragrance microcapsule encapsulation reactions and shell crosslinked-structure studies | |
Amino resin crosslinking raw material | 50-00-0 | Formaldehyde solution | Molecular biology grade, ≥36.0% in H₂O (T), contains 10–15% methanol as stabilizer | Amino resin crosslinking raw material; used for studies on urea–formaldehyde or melamine–formaldehyde shell encapsulation reactions | |
Ionic crosslinking agent | 10043-52-4 | Calcium chloride | Anhydrous grade, ≥97% | Forms ionically crosslinked gels with sodium alginate; used for fragrance gel embedding, microparticle solidification, and water-responsive release studies | |
Acrylic polymer shell material | 9011-14-7 | Poly(methyl methacrylate) (PMMA) | Average Mw ~15,000, by GPC; powder | Hydrophobic polymer material; used for fragrance shell-layer models, diffusion barriers, and polymer embedding studies | |
Amino resin shell precursor | 108-78-1 | Melamine | ≥99% | Melamine–formaldehyde shell precursor; used for fragrance microcapsule formation, shell strength, and release-resistance studies | |
Polyurea shell-chain extender | 107-15-3 | E112643 | Ethylenediamine, regulated explosive precursor | Distilled grade, ≥99.5% | Polyamine chain extender; used for interfacial polymerization of polyurea microcapsules, shell formation, and crosslinking-density adjustment studies |
Ionic crosslinking agent | 7758-29-4 | Sodium tripolyphosphate | AR, ≥98% | Can form ionically crosslinked structures with chitosan; used for natural polymer microparticle preparation and fragrance embedding studies | |
Potentially biodegradable polymer shell material | 26100-51-6 | Polylactic acid | Mw ~60,000 | Potentially biodegradable polyester material; used for fragrance sustained-release particles, polymer wall materials, and degradation-control studies | |
Polyurethane/polyurea encapsulation monomer | 822-06-0 | Hexamethylene diisocyanate (HDI) | Moligand™, ≥99% | Diisocyanate monomer; used for polyurea or polyurethane shell encapsulation, interfacial polymerization, and shell-density studies | |
Polyurea shell crosslinking agent | 111-40-0 | Diethylenetriamine | ≥99% | Polyamine crosslinking agent; used for polyurea shell crosslinking, capsule mechanical strength, and fragrance release-resistance studies | |
Polyurethane/polyurea encapsulation monomer | 4098-71-9 | Isophorone diisocyanate, mixture of isomers (IPDI) | ≥99% | Alicyclic diisocyanate monomer; used for construction of polyurea or polyurethane fragrance microcapsule shells and medium-resistance studies |
Table 5. Representative Aroma Chemicals and Release-Evaluation Raw Materials
Category | CAS No. | Aladdin Cat. No. | Name | Specification or Purity | Product Features and Applications |
Solid aromatic aldehyde fragrance material | 121-33-5 | Vanillin | AR, ≥99% | Low-volatility sweet aroma molecule; used for later-stage release of powdered fragrances, embedding of solid aroma chemicals, and aroma-retention evaluation | |
Monoterpene fragrance material | 5989-27-5 | (R)-(+)-Limonene | ≥95%, contains 0.03% alpha-tocopherol as stabilizer | Highly volatile terpene aroma chemical; used for adsorption protection, oxidative stability, and top-note release evaluation | |
Phenolic fragrance material | 97-53-0 | Eugenol | Moligand™, ≥99% | Phenolic hydroxyl-containing aromatic molecule; used for studies on carrier hydrogen-bonding interactions, oxidative stability, and sustained-release behavior | |
Monoterpene alcohol fragrance material | 78-70-6 | Linalool | Moligand™, ≥98% | Typical floral alcohol molecule; used for cyclodextrin inclusion, porous adsorption, and volatile-release evaluation | |
Monoterpene aldehyde fragrance material | 5392-40-5 | Citral | Moligand™, ≥97%, mixture of cis and trans | Unsaturated aldehyde aroma chemical; used for embedding protection, oxidative stability, and aroma-attenuation studies | |
Synthetic musk fragrance material | 1222-05-5 | Galaxolide | 50% in diethyl phthalate solution | Low-volatility fixative-type molecule; used for later-stage lasting aroma, hydrophobic molecule partitioning, and release-curve studies | |
Monoterpene alcohol fragrance material | 106-22-9 | β-Citronellol | ≥95% | Rose-like alcohol molecule; used for fragrance adsorption, inclusion equilibrium, and volatile-release evaluation | |
Ester fragrance material | 140-11-4 | Benzyl acetate | ≥99% | Floral ester molecule; used for cyclodextrin inclusion, spray-drying embedding, and aroma-retention studies | |
Monoterpene alcohol fragrance material | 106-24-1 | Geraniol | ≥98%, mixture of isomers | Floral alcohol molecule; used for porous-carrier adsorption, inclusion immobilization, and release-difference studies | |
Jasmine-type ester fragrance material | 24851-98-7 | Methyl dihydrojasmonate, mixture of trans and cis isomers | ≥96% | Middle-to-late-note diffusive molecule; used for fragrance release curves, later-stage aroma retention, and carrier-partitioning studies |
Note: The above are representative Aladdin products related to scientific research and formulation studies. For more product specifications, grades, and COA information, please search by “product name/CAS/catalog number” on the Aladdin official website. Some monomers, crosslinking agents, and reaction precursors listed in the tables are only suitable for controlled experiments or industrial synthesis research and do not mean that they can be directly used in finished consumer-product formulations. Actual use must comply with SDS requirements, hazardous chemical management requirements, residual-control requirements, and applicable regulations in the target market.
For more related articles, please see below:
Fragrance Science: From “Smells Nice” to a Chemical World That Can Be Studied and Standardized
Applications of Flavors and Fragrances in the Food Industry